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Abd-Elhamid TH, Althumairy D, Bani Ismail M, Abu Zahra H, Seleem HS, Hassanein EHM, Ali FEM, Mahmoud AR. Neuroprotective effect of diosmin against chlorpyrifos-induced brain intoxication was mediated by regulating PPAR-γ and NF-κB/AP-1 signals. Food Chem Toxicol 2024; 193:114967. [PMID: 39197517 DOI: 10.1016/j.fct.2024.114967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 08/23/2024] [Accepted: 08/25/2024] [Indexed: 09/01/2024]
Abstract
Chlorpyrifos (CPF) is a widely used organophosphate (OP) pesticide. Unfortunately, pesticides are known to cause neuronal intoxication. Diosmin (DS) is an antioxidant, anti-inflammatory, and neuroprotective flavonoid with high efficacy and safety. We plan to investigate the efficacy of DS in treating CPF-induced neurotoxicity, as well as the mechanisms underlying the protective effects. In our study, rats were randomized into 5 groups: control, DS (50 mg/kg), CPF (10 mg/kg), CPF + DS (25 mg/kg), and CPF + DS (50 mg/kg). The results indicated that DS ameliorated neuronal intoxication induced by CPF, evidenced by decreasing Tau, p-Tau, and β-amyloid. Histological examinations support these findings. DS significantly ameliorated CPF-induced neuronal oxidative injury by decreasing MDA content and elevating GSH, GST, and SOD levels mediated by PPAR-γ upregulation. DS suppressed CPF-induced brain inflammation by decreasing MPO enzymatic activity and TNF-α, IL-1β, and IL-6 levels mediated by downregulation of NF-κB/AP-1(c-FOS and c-JUN) signal. Of note, DS protective effects were dose dependent. In conclusion, our data suggested that DS was a promising therapeutic strategy for attenuating CPF-induced neuronal intoxication by restoring oxidant-antioxidant balance and inhibiting inflammatory response in brain tissues.
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Affiliation(s)
- Tarek Hamdy Abd-Elhamid
- Department of Histology and Cell Biology, Faculty of Medicine, Assiut University, Assiut, 71515, Egypt; Department of Basic Medical Sciences, Faculty of Medicine, Aqaba Medical Sciences University, Aqaba, 77110, Jordan
| | - Duaa Althumairy
- Department of Biological Sciences, Faculty of Science, King Faisal University, Al-Ahsa, 31982, Saudi Arabia
| | - Mohammad Bani Ismail
- Department of Basic Medical Sciences, Faculty of Medicine, Aqaba Medical Sciences University, Aqaba, 77110, Jordan
| | - Hamad Abu Zahra
- Department of Biological Sciences, Faculty of Science, King Faisal University, Al-Ahsa, 31982, Saudi Arabia
| | - Hanan S Seleem
- Histology Department, Faculty of Medicine, Menoufia University, Shebin ElKoum-Menoufia, Egypt; Department of Basic Medical Sciences, Unaizah College of Medicine and Medical Sciences, Qassim University, Kingdom of Saudi Arabia
| | - Emad H M Hassanein
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Al-Azhar University, Assiut Branch, Assiut, 71524, Egypt
| | - Fares E M Ali
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Al-Azhar University, Assiut Branch, Assiut, 71524, Egypt; Michael Sayegh, Faculty of Pharmacy, Aqaba University of Technology, Aqaba, 77110, Jordan.
| | - Amany Refaat Mahmoud
- Department of Human Anatomy and Embryology, Faculty of Medicine, Assiut University, Assiut, 71515, Egypt; Department of Anatomy and Histology, College of Medicine, Qassim University, Kingdom of Saudi Arabia
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2
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Hawkey AB, Natarajan S, Kelly O, Gondal A, Wells C, Jones ML, Rezvani AH, Murphy SK, Levin ED. Persisting neurobehavioral consequences of daily or intermittent paternal cannabis administration in F1 and F2 Rats. Neurotoxicology 2024; 103:27-38. [PMID: 38810733 DOI: 10.1016/j.neuro.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/16/2024] [Accepted: 05/22/2024] [Indexed: 05/31/2024]
Abstract
Repeated paternal preconception exposure to Δ9-tetrahydrocannabinol (Δ9-THC) alone or together with the other constituents in a cannabis extract has been shown in our earlier studies in rats to cause significant neurobehavioral impairment in their offspring. In the current study, we compared the effects of daily cannabis extract (CE) exposure to cannabis on two consecutive days per week, modeling weekend cannabis use in human. The CE contained Δ9-THC as well as cannabidiol and cannabinol. We also extended the investigation of the study to cross-generational effects of grand-paternal cannabis exposure on the F2 generation and included testing the effects of paternal cannabis exposure on responding for opiate self-administration in F1 and F2 generation offspring. We replicated the findings of neurobehavioral impairment in F1 offspring of male rats exposed to cannabis extract containing 4 mg/kg/day of Δ9-THC daily for four weeks prior to mating with drug naïve females. The 4-week cannabis extract exposure caused a significant decrease in weight gain in the male rats exposed daily. In contrast, their offspring showed significantly greater body weights and anogenital distances (AGD) in the third to fourth weeks after birth. The behavioral effects seen in the F1 generation were increased habituation of locomotor activity in the figure-8 maze in female offspring and increased lever pressing for the opiate drug remifentanil in male offspring. The F2 generation showed significantly impaired negative geotaxis and an elimination of the typical sex-difference in locomotor activity, with effects not seen in the F1 generation. This study shows that daily paternal cannabis exposure for four weeks prior to mating causes significant neurobehavioral impairment in the F1 and F2 offspring. Intermittent exposure on two consecutive days per week for four weeks caused comparable neurobehavioral impairment. In sum, there should be concern about paternal as well as maternal exposure to cannabis concerning neurobehavioral development of their offspring.
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Affiliation(s)
- Andrew B Hawkey
- Department of Biomedical Sciences, Midwestern University, Downers Grove, IL, USA; Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Sarabesh Natarajan
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Olivia Kelly
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Anas Gondal
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Corinne Wells
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Michelle Louise Jones
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Amir H Rezvani
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Susan K Murphy
- Department of Obstetrics and Gynecology, Duke University School of Medicine, Durham, NC, USA
| | - Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA.
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Zhao S, Liu J, Miao D, Sun H, Zhang P, Jia H. Activation of persulfate for the degradation of ethyl-parathion in soil: Combined effects of microwave with biochar. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119930. [PMID: 38160544 DOI: 10.1016/j.jenvman.2023.119930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 11/30/2023] [Accepted: 12/23/2023] [Indexed: 01/03/2024]
Abstract
Sulfate radical (SO4•-), formed by persulfate (PS) activation during advanced oxidation process (AOPs), can be used for the remediation of organic contaminated soil. However, the role of biochar and microwave (MW) in the activation of PS is not fully understood, especially the corresponding mechanism. Herein, biochar combined with MW was used to activate PS for the remediation of ethyl-parathion (PTH)-polluted soil. The dynamic evolutions of PTH under different conditions, such as biochar content, particle size, reaction temperature, and the degradation mechanisms of PTH were also systematically investigated. Significant enhancement performance on PTH removal was observed after adding biochar, which was 88.78% within 80 min. Meanwhile, activating temperature exhibited remarkable abilities to activate PS for PTH removal. The higher content of adsorption sites in nano-biochar facilitated the removal of PTH. Furthermore, chemical probe tests coupled with quenching experiments confirmed that the decomposition of PS into active species, such as SO4•-, •OH, O2•- and 1O2, contributed to the removal of PTH in biochar combined with MW system, which could oxidize PTH into oxidative products, including paraoxon, 4-ethylphenol, and hydroquinone. The results of this study provide valuable insights into the synergistic effects of biochar and MW in the PS activation, which is helpful for the potential application of biochar materials combined with MW-activated PS in the remediation of pesticide-polluted soils.
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Affiliation(s)
- Song Zhao
- College of Ecology and Environment, Xinjiang University, Urumqi, 830046, PR China; Key Laboratory of Oasis Ecology of Education Ministry, Urumqi, 830046, PR China.
| | - Jinbo Liu
- College of Resources and Environment, Northwest A & F University, Yangling, 712100, PR China
| | - Duo Miao
- Department of Science and Technology, Xinjiang University, Urumqi, 830046, PR China
| | - Hongwen Sun
- Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, PR China
| | - Peng Zhang
- Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, PR China
| | - Hanzhong Jia
- College of Resources and Environment, Northwest A & F University, Yangling, 712100, PR China.
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Mosier JA, Hybart RL, Lewis AM, Alugubelly N, Mohammed AN, Carr RL. Inhibition of Serum Esterases in Juvenile Rats Repeatedly Exposed to Low Levels of Chlorpyrifos. INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENVIRONMENTAL SCIENCE AND TOXICOLOGY 2022; 5:10.15226/2572-3162/5/1/00133. [PMID: 36118291 PMCID: PMC9477121 DOI: 10.15226/2572-3162/5/1/00133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Chlorpyrifos (CPF) is an organophosphorus insecticide that has gained significant attention cue to the reported toxicity associated with developmental exposure. While the canonical mechanism of toxicity of CPF involves the inhibition of brain acetylcholinesterase (AChE), we have reported that exposure of juvenile rats to levels of CPF that do not yield any inhibition of brain AChE results in neurobehavioral alterations at later ages. However, it is unclear what effect exposure to these low levels of CPF has on blood esterase activities which are frequently used not only as biomarkers of exposure but also to set exposure levels in risk assessment. To determine this, male and female rat pups were exposed orally from postnatal day 10 to 16 to either corn oil (vehicle) or 0.5, 0.75, or 1.0 mg/kg CPF. At 12 h after the final exposure, serum cholinesterase (ChE), butyrylcholinesterase (BChE), and carboxylesterase (CES), and red blood cell (RBC) and brain AChE activities were determined. There were no differences between sexes in either the controls or individual treatments for all enzymes. Only the highest dosage of 1.0 mg/kg CPF yielded significant brain AChE inhibition (22-24%) but all dosages significantly inhibited the blood esterases with inhibition being highest with serum CES (65-85%) followed by serum BChE (57-76%), RBC AChE (35-65%), and then serum ChE (16-32%). Our data verify that blood esterases are inhibited at dosages of CPF that alter neurobehavioral performance in the absence of effects on brain AChE activity.
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Affiliation(s)
- Jenna A. Mosier
- Center for Environmental Health Sciences, Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, MS, USA
| | - Rachel L. Hybart
- Center for Environmental Health Sciences, Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, MS, USA
| | - Aubrey M. Lewis
- Center for Environmental Health Sciences, Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, MS, USA
| | - Navatha Alugubelly
- Center for Environmental Health Sciences, Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, MS, USA
| | - Afzaal N. Mohammed
- Center for Environmental Health Sciences, Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, MS, USA
| | - Russell L. Carr
- Center for Environmental Health Sciences, Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, MS, USA
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5
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Hawkey AB, Pippen E, Kenou B, Holloway Z, Slotkin TA, Seidler FJ, Levin ED. Persistent neurobehavioral and neurochemical anomalies in middle-aged rats after maternal diazinon exposure. Toxicology 2022; 472:153189. [PMID: 35452779 PMCID: PMC9655883 DOI: 10.1016/j.tox.2022.153189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/13/2022] [Accepted: 04/15/2022] [Indexed: 11/17/2022]
Abstract
Diazinon is an organophosphate pesticide that has a history of wide use. Developmental exposures to organophosphates lead to neurobehavioral changes that emerge early in life and can persist into adulthood. However, preclinical studies have generally evaluated changes through young adulthood, whereas the persistence or progression of deficits into middle age remain poorly understood. The current study evaluated the effects of maternal diazinon exposure on behavior and neurochemistry in middle age, at 1 year postpartum, comparing the results to our previous studies of outcomes at adolescence and in young adulthood (4 months of age) (Hawkey 2020). Female rats received 0, 0.5 or 1.0 mg/kg/day of diazinon via osmotic minipump throughout gestation and into the postpartum period. The offspring were tested on a battery of locomotor, affective, and cognitive tests at young adulthood and during middle age. Some of the neurobehavioral consequences of developmental DZN seen during adolescence and young adulthood faded with continued aging, whereas other neurobehavioral effects emerged with aging. At middle age, the rats showed few locomotor effects, in contrast to the locomotor hyperactivity that had been observed in adolescence. Notably, though, DZN exposure during development impaired reference memory performance in middle-aged males, an effect that had not been seen in the younger animals. Likewise, middle-aged females exposed to DZN showed deficient attentional accuracy, an effect not seen in young adults. Across adulthood, the continued potential for behavioral defects was associated with altered dopaminergic function, characterized by enhanced dopamine utilization that was regionally-selective (striatum but not frontal/parietal cortex). This study shows that the neurobehavioral impairments from maternal low dose exposure to diazinon not only persist, but may continue to evolve as animals enter middle age.
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Affiliation(s)
- Andrew B Hawkey
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, USA
| | - Erica Pippen
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, USA
| | - Bruny Kenou
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, USA
| | - Zade Holloway
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, USA
| | - Theodore A Slotkin
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, USA
| | - Frederic J Seidler
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, USA
| | - Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, USA.
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6
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Latchney SE, Majewska AK. Persistent organic pollutants at the synapse: Shared phenotypes and converging mechanisms of developmental neurotoxicity. Dev Neurobiol 2021; 81:623-652. [PMID: 33851516 DOI: 10.1002/dneu.22825] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 02/27/2021] [Accepted: 04/09/2021] [Indexed: 12/18/2022]
Abstract
The developing nervous system is sensitive to environmental and physiological perturbations in part due to its protracted period of prenatal and postnatal development. Epidemiological and experimental studies link developmental exposures to persistent organic pollutants (POPs) including polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polybrominated diphenyl ethers, and benzo(a)pyrene to increased risk for neurodevelopmental disorders in children. Mechanistic studies reveal that many of the complex cellular processes that occur during sensitive periods of rapid brain development are cellular targets for developmental neurotoxicants. One area of research interest has focused on synapse formation and plasticity, processes that involve the growth and retraction of dendrites and dendritic spines. For each chemical discussed in this review, we summarize the morphological and electrophysiological data that provide evidence that developmental POP exposure produces long-lasting effects on dendritic morphology, spine formation, glutamatergic and GABAergic signaling systems, and synaptic transmission. We also discuss shared intracellular mechanisms, with a focus on calcium and thyroid hormone homeostasis, by which these chemicals act to modify synapses. We conclude our review highlighting research gaps that merit consideration when characterizing synaptic pathology elicited by chemical exposure. These gaps include low-dose and nonmonotonic dose-response effects, the temporal relationship between dendritic growth, spine formation, and synaptic activity, excitation-inhibition balance, hormonal effects, and the need for more studies in females to identify sex differences. By identifying converging pathological mechanisms elicited by POP exposure at the synapse, we can define future research directions that will advance our understanding of these chemicals on synapse structure and function.
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Affiliation(s)
- Sarah E Latchney
- Department of Biology, St. Mary's College of Maryland, St. Mary's City, MD, USA.,Department of Neuroscience, Del Monte Institute for Neuroscience, University of Rochester Medical Center, Rochester, NY, USA
| | - Ania K Majewska
- Department of Neuroscience, Del Monte Institute for Neuroscience, University of Rochester Medical Center, Rochester, NY, USA.,Center for Visual Science, University of Rochester Medical Center, Rochester, NY, USA
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7
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Holloway ZR, Hawkey AB, Torres AK, Evans J, Pippen E, White H, Katragadda V, Kenou B, Wells C, Murphy SK, Rezvani AH, Levin ED. Paternal cannabis extract exposure in rats: Preconception timing effects on neurodevelopmental behavior in offspring. Neurotoxicology 2020; 81:180-188. [DOI: 10.1016/j.neuro.2020.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/14/2020] [Accepted: 10/14/2020] [Indexed: 01/22/2023]
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Olisah C, Adams JB. Systematic mapping of organophosphate contaminant (OPC) research trends between 1990 and 2018. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2020; 42:3481-3505. [PMID: 32435924 DOI: 10.1007/s10653-020-00594-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Since the addition of polybrominated diphenyls and organochlorine pesticides (OCPs) to the world banned list, toxic organophosphate contaminants (OPCs) such as organophosphate flame retardants and organophosphate pesticides have been, respectively, used as substitutes. These chemicals are reported to be more toxic than their halogenated counterparts. It is rare to find a study that focuses on visualising the publication trends of these chemical classes. In this study, we employed a bibliometric model to systematically map research activities between 1990 and 2018 using OPC articles retrieved from the WoS and Scopus databases. A total of 1090 articles were retrieved from the hybrid databases with an article/author and author/article ratio of 0.33 and 3.02, respectively. Articles on OPC studies were positively correlated with the number of years (r2 = 0.96; y = 0.23x2 - 3.82x + 27.90) suggesting an increase in the number of articles on this subject in future. The USA ranked first in terms of articles (n = 245) and citations (n = 12,922) followed by China and India (203 and 89 articles, respectively). Articles from China and the USA had strong collaboration with other countries. Research priorities and top author keywords included pesticides (n = 112), organophosphate (n = 83) and acetylcholinesterase (n = 60) and were also well represented in keywords-plus. Developed countries had higher outputs compared to developing countries. It was observed that from our thematic literature classifications, human toxicity, ecotoxicological impacts, and environmental monitoring of OPCs were of greater importance to scholars, thus indicating the direction of future research. Futuristic studies need to foster partnership with policymakers, journalists, consultants, farmers, artisans and community workers on OPC research. This will not only enhance scientific communication and community engagement but will also increase the awareness of these pollutants to the general public.
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Affiliation(s)
- Chijioke Olisah
- Botany Department, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, 6031, South Africa.
| | - Janine B Adams
- Botany Department, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, 6031, South Africa
- DST/NRF Research Chair in Shallow Water Ecosystem, Nelson Mandela University, Port Elizabeth, 6031, South Africa
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Gestational exposures to organophosphorus insecticides: From acute poisoning to developmental neurotoxicity. Neuropharmacology 2020; 180:108271. [PMID: 32814088 DOI: 10.1016/j.neuropharm.2020.108271] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 07/03/2020] [Accepted: 08/10/2020] [Indexed: 11/22/2022]
Abstract
For over three-quarters of a century, organophosphorus (OP) insecticides have been ubiquitously used in agricultural, residential, and commercial settings and in public health programs to mitigate insect-borne diseases. Their broad-spectrum insecticidal effectiveness is accounted for by the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that catalyzes acetylcholine (ACh) hydrolysis, in the nervous system of insects. However, because AChE is evolutionarily conserved, OP insecticides are also toxic to mammals, including humans, and acute OP intoxication remains a major public health concern in countries where OP insecticide usage is poorly regulated. Environmental exposures to OP levels that are generally too low to cause marked inhibition of AChE and to trigger acute signs of intoxication, on the other hand, represent an insidious public health issue worldwide. Gestational exposures to OP insecticides are particularly concerning because of the exquisite sensitivity of the developing brain to these insecticides. The present article overviews and discusses: (i) the health effects and therapeutic management of acute OP poisoning during pregnancy, (ii) epidemiological studies examining associations between environmental OP exposures during gestation and health outcomes of offspring, (iii) preclinical evidence that OP insecticides are developmental neurotoxicants, and (iv) potential mechanisms underlying the developmental neurotoxicity of OP insecticides. Understanding how gestational exposures to different levels of OP insecticides affect pregnancy and childhood development is critical to guiding implementation of preventive measures and direct research aimed at identifying effective therapeutic interventions that can limit the negative impact of these exposures on public health.
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Akpa AR, Ayo JO, Mika'il HG, Zakari FO. Protective effect of fisetin against subchronic chlorpyrifos-induced toxicity on oxidative stress biomarkers and neurobehavioral parameters in adult male albino mice. Toxicol Res 2020; 37:163-171. [PMID: 33868974 DOI: 10.1007/s43188-020-00049-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 05/12/2020] [Accepted: 05/25/2020] [Indexed: 12/13/2022] Open
Abstract
Chlorpyrifos (CPF), a chlorinated organophosphate insecticide that is widely used in agriculture and public health, has neurotoxic effects in animals. In addition to acetylcholinesterase inhibition, CPF has been shown to induce alterations such as oxidative stress and lipid peroxidation. Fisetin is a dietary flavonol that protects the brain tissue against oxidative stress by modulating the activity of antioxidant enzymes. This study was designed to investigate the protective role of fisetin against brain oxidative damages and neurobehavioral parameters induced by subchronic oral exposure to CPF in albino mice. Adult albino mice (males, n = 32, weighing 20 ~ 25 g) were assigned randomly into 4 groups and treated accordingly for 7 weeks as follows: Group 1(S/OIL): served as the control group and were given 2 ml/kg of soya oil; Group 2 (CPF): received CPF (6.6 mg/kg; 1/5th of the LD50); Group 3 (FIS): fisetin (15 mg/kg) and Group 4 (FIS + CPF): received fisetin at 15 mg/kg, followed by CPF (6.6 mg/kg) 30 min later. Co-treatment with FIS + CPF mitigated the increase in brain malondialdehyde concentration (0.28 ± 0.02 nmol/mg) and orchestrated the increase in the activities of catalase (81.35 ± 7.26 µ/mg), superoxide dismutase (93.03 ± 6.63 IU/mL), glutathione peroxidase (68.76 ± 3.554 nmol/mL) and acetylcholinesterase (11.59 ± 0.72 nmol/min/mL) when compared to the CPF group. The result showed that deficits in motor strength and excitability scores induced by subchronic CPF were mitigated by fisetin administration. It was concluded that fisetin has a protective potential in mitigating against oxidative stress and damages in the brain tissues, induced by subchronic exposure to CPF in adult male albino mice.
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Affiliation(s)
- Amaka Rosita Akpa
- Department of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria, Nigeria
| | - Joseph Olusegun Ayo
- Department of Veterinary Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria, Nigeria
| | - Hudu Garba Mika'il
- Department of Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Abuja, Abuja, Nigeria
| | - Friday Ocheja Zakari
- Department of Veterinary Physiology, Biochemistry and Pharmacology, Faculty of Veterinary Medicine, University of Jos, Jos, Nigeria
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11
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Rock KD, St Armour G, Horman B, Phillips A, Ruis M, Stewart AK, Jima D, Muddiman DC, Stapleton HM, Patisaul HB. Effects of Prenatal Exposure to a Mixture of Organophosphate Flame Retardants on Placental Gene Expression and Serotonergic Innervation in the Fetal Rat Brain. Toxicol Sci 2020; 176:203-223. [PMID: 32243540 PMCID: PMC7357193 DOI: 10.1093/toxsci/kfaa046] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
There is a growing need to understand the potential neurotoxicity of organophosphate flame retardants (OPFRs) and plasticizers because use and, consequently, human exposure, is rapidly expanding. We have previously shown in rats that developmental exposure to the commercial flame retardant mixture Firemaster 550 (FM 550), which contains OPFRs, results in sex-specific behavioral effects, and identified the placenta as a potential target of toxicity. The placenta is a critical coordinator of fetal growth and neurodevelopment, and a source of neurotransmitters for the developing brain. We have shown in rats and humans that flame retardants accumulate in placental tissue, and induce functional changes, including altered neurotransmitter production. Here, we sought to establish if OPFRs (triphenyl phosphate and a mixture of isopropylated triarylphosphate isomers) alter placental function and fetal forebrain development, with disruption of tryptophan metabolism as a primary pathway of interest. Wistar rat dams were orally exposed to OPFRs (0, 500, 1000, or 2000 μg/day) or a serotonin (5-HT) agonist 5-methoxytryptamine for 14 days during gestation and placenta and fetal forebrain tissues collected for analysis by transcriptomics and metabolomics. Relative abundance of genes responsible for the transport and synthesis of placental 5-HT were disrupted, and multiple neuroactive metabolites in the 5-HT and kynurenine metabolic pathways were upregulated. In addition, 5-HTergic projections were significantly longer in the fetal forebrains of exposed males. These findings suggest that OPFRs have the potential to impact the 5-HTergic system in the fetal forebrain by disrupting placental tryptophan metabolism.
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Affiliation(s)
- Kylie D Rock
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
| | - Genevieve St Armour
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
| | - Brian Horman
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
| | - Allison Phillips
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708
| | - Matthew Ruis
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708
| | - Allison K Stewart
- Molecular Education, Technology, and Research Innovation Center, North Carolina State University, Raleigh, North Carolina 27695
| | - Dereje Jima
- Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina 27695
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina 27695
| | - David C Muddiman
- Molecular Education, Technology, and Research Innovation Center, North Carolina State University, Raleigh, North Carolina 27695
| | - Heather M Stapleton
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708
| | - Heather B Patisaul
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
- Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina 27695
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Holloway ZR, Hawkey AB, Pippin E, White H, Wells C, Kenou B, Rezvani AH, Murphy SK, Levin ED. Paternal factors in neurodevelopmental toxicology: THC exposure of male rats causes long-lasting neurobehavioral effects in their offspring. Neurotoxicology 2020; 78:57-63. [PMID: 32045580 DOI: 10.1016/j.neuro.2020.01.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 01/17/2020] [Accepted: 01/24/2020] [Indexed: 01/03/2023]
Abstract
The potential health risks of cannabis are of growing concern, including effects on reproduction and development. Extensive research has investigated risks associated with maternal exposure to THC during gestation and its impacts on the development of offspring, but little research has been done regarding paternal THC exposure effects prior to conception. We have previously found that paternal THC exposure in rats causes changes in sperm methylation. In an initial study we also showed that a 12-day paternal THC exposure prior to conception alters locomotor activity and impairs cognitive function of their offspring. This study investigated the cross-generational effects of chronic paternal THC exposure in rats (0, 2, or 4 mg/kg/day SC for 28 days) prior to mating with drug naïve females. The offspring of THC-exposed male rats had significant alterations in locomotor activity and cognitive function. Specifically, during adolescence there was significant locomotor hyperactivity in the offspring of males exposed to 2 mg/kg/day of THC. During the novel object recognition task, the controls maintained their relative preference for the novel object across the duration of the ten-min session while the rats whose fathers received THC (2 mg/kg/day) showed a significantly greater drop-off in interest in the novel object during the second half of the session. Learning in the radial-arm maze was significantly delayed in the offspring of males exposed to 4 mg/kg/day of THC. This study shows that premating chronic paternal THC exposure at multiple dose regimens can cause long-lasting detrimental behavioral effects in their offspring, including abnormal locomotor activity and impaired cognitive function. Future studies should investigate the underlying mechanisms driving these aberrant developmental outcomes and seek to identify possible treatments of alleviation in the presence of paternal THC exposure.
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Affiliation(s)
- Zade R Holloway
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Andrew B Hawkey
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Erica Pippin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Hannah White
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Corinne Wells
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Bruny Kenou
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Amir H Rezvani
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Susan K Murphy
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA
| | - Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA.
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Carr RL, Alugubelly N, de Leon K, Loyant L, Mohammed AN, Patterson ME, Ross MK, Rowbotham NE. Inhibition of fatty acid amide hydrolase by chlorpyrifos in juvenile rats results in altered exploratory and social behavior as adolescents. Neurotoxicology 2020; 77:127-136. [PMID: 31931040 DOI: 10.1016/j.neuro.2020.01.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 12/31/2019] [Accepted: 01/07/2020] [Indexed: 12/26/2022]
Abstract
The organophosphorus insecticide chlorpyrifos (CPF) is suspected to cause developmental neurotoxicity in children leading to long term effects. Developmental exposure of rat pups to CPF at low levels disrupts degradation of the brain endocannabinoids through the inhibition of fatty acid amide hydrolase (FAAH) and decreases the reactivity of juvenile rats in an emergence test. In this study, we further investigated the effects of developmental CPF exposure on behavior but also included exposure to PF-04457845, a specific inhibitor of FAAH, for comparison of behavior altered by FAAH inhibition with behavior altered by CPF. Ten day old rat pups were exposed orally either to 0.5, 0.75, or 1.0 mg/kg CPF or 0.02 mg/kg PF-04457845 daily for 7 days. In an open field (day 23), the high CPF and PF-04457845 groups exhibited increased motor activity but no differences in the time spent in the field's center. In an elevated plus maze (day 29), all treatment groups had increased open arm activity but ethological behaviors associated with anxiety were not altered. Behaviors in the maze associated with increased general activity and exploratory drive were increased. Social interactions (day 36) were measured and all treatment groups exhibited increased levels of play behavior. The similarities in behavior between PF-04457845 and CPF suggest that enhanced endocannabinoid signaling during the exposure period plays a role in the persistent alteration of behavior observed following developmental CPF exposure.
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Affiliation(s)
- Russell L Carr
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA.
| | - Navatha Alugubelly
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Kathryne de Leon
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Louise Loyant
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Afzaal N Mohammed
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - M Elizabeth Patterson
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Matthew K Ross
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Nicole E Rowbotham
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
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Gestational and perinatal exposure to diazinon causes long-lasting neurobehavioral consequences in the rat. Toxicology 2019; 429:152327. [PMID: 31704166 DOI: 10.1016/j.tox.2019.152327] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 09/16/2019] [Accepted: 10/30/2019] [Indexed: 02/08/2023]
Abstract
Diazinon is a widely-used organophosphate pesticide. Pulsatile exposure to diazinon during neonatal development has previously been shown cause long-term neurobehavioral impairments in rats. However, the effects of chronic low concentration exposures during perinatal development remain unclear. This experiment evaluated such effects in Sprague-Dawley rats by implanting osmotic pumps in breeder females prior to conception (N = 13-15 litters per condition) which then delivered chronic, zero order kinetic low-level infusions of 0, 114 or 228 ug/day of diazinon throughout pregnancy. One male and one female from each litter was assessed with a battery of behavioral tests that continued from four weeks of age into adulthood. Litter was used as the unit of variance for the analysis of variance test of significance, with sex as a within litter factor. Diazinon treatment condition was the between subjects factor and time or sessions were repeated measures. Chronic diazinon exposure from pre-mating until the neonatal period caused a significant (p < 0.05) increase in percent of time spent on the open arms of the elevated plus maze, an index of risk-taking behavior. Gestational and lactational diazinon exposure also caused a significant (p < 0.05) degree of hyperactivity in the Figure-8 apparatus during adolescence, specifically affecting the early part of the hour-long test session. This effect had dissipated by the time the rats reached adulthood. Diazinon exposure also caused a significant impairment in novel object recognition, a test of cognitive function. Offspring exposed to 228 ug/day diazinon (p < 0.05) showed significantly less preference for the novel vs. familiar object than controls during the first five minutes of the novel object recognition test.
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15
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Aluminum affects neural phenotype determination of embryonic neural progenitor cells. Arch Toxicol 2019; 93:2515-2524. [PMID: 31363819 DOI: 10.1007/s00204-019-02522-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 07/18/2019] [Indexed: 10/26/2022]
Abstract
Aluminum (Al) is a neurotoxin and is associated with the etiology of neurodegenerative diseases, such as Alzheimer's disease (AD). The Al-free ion (Al3+) is the biologically reactive and toxic form. However, the underlying mechanisms of Al toxicity in the brain remain unclear. Here, we evaluated the effects of Al3+ (in the chloride form-AlCl3) at different concentrations (0.1-100 µM) on the morphology, proliferation, apoptosis, migration and differentiation of neural progenitor cells (NPCs) isolated from embryonic telencephalons, cultured as neurospheres. Our results reveal that Al3+ at 100 µM reduced the number and diameter of neurospheres. Cell cycle analysis showed that Al3+ had a decisive function in proliferation inhibition of NPCs during neural differentiation and induced apoptosis on neurospheres. In addition, 1 µM Al3+ resulted in deleterious effects on neural phenotype determination. Flow cytometry and immunocytochemistry analysis showed that Al3+ promoted a decrease in immature neuronal marker β3-tubulin expression and an increase in co-expression of the NPC marker nestin and glial fibrillary acidic protein. Thus, our findings indicate that Al3+ caused cellular damage and reduced proliferation and migration, resulting in global inhibition of NPC differentiation and neurogenesis.
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Perez-Fernandez C, Flores P, Sánchez-Santed F. A Systematic Review on the Influences of Neurotoxicological Xenobiotic Compounds on Inhibitory Control. Front Behav Neurosci 2019; 13:139. [PMID: 31333425 PMCID: PMC6620897 DOI: 10.3389/fnbeh.2019.00139] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/06/2019] [Indexed: 01/24/2023] Open
Abstract
Background: Impulsive and compulsive traits represent a variety of maladaptive behaviors defined by the difficulties to stop an improper response and the control of a repeated behavioral pattern without sensitivity to changing contingencies, respectively. Otherwise, human beings are continuously exposed to plenty neurotoxicological agents which have been systematically linked to attentional, learning, and memory dysfunctions, both preclinical and clinical studies. Interestingly, the link between both impulsive and compulsive behaviors and the exposure to the most important xenobiotic compounds have been extensively developed; although the information has been rarely summarized. For this, the present systematic review schedule and analyze in depth the most important works relating different subtypes of the above-mentioned behaviors with 4 of the most important xenobiotic compounds: Lead (Pb), Methylmercury (MeHg), Polychlorinated biphenyls (PCB), and Organophosphates (OP) in both preclinical and clinical models. Methods: Systematic search strategy on PubMed databases was developed, and the most important information was structured both in text and in separate tables based on rigorous methodological quality assessment. Results: For Lead, Methylmercury, Polychlorinated biphenyls and organophosphates, a total of 44 (31 preclinical), 34 (21), 38 (23), and 30 (17) studies were accepted for systematic synthesis, respectively. All the compounds showed an important empirical support on their role in the modulation of impulsive and, in lesser degree, compulsive traits, stronger and more solid in animal models with inconclusive results in humans in some cases (i.e., MeHg). However, preclinical and clinical studies have systematically focused on different subtypes of the above-mentioned behaviors, as well as impulsive choice or habit conformations have been rarely studied. Discussion: The strong empirical support in preclinical studies contrasts with the lack of connection between preclinical and clinical models, as well as the different methodologies used. Further research should be focused on dissipate these differences as well as deeply study impulsive choice, decision making, risk taking, and cognitive flexibility, both in experimental animals and humans.
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Affiliation(s)
| | - Pilar Flores
- Department of Psychology and Health Research Center, University of Almería, Almería, Spain
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17
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Alipour V, Hoseinpour F, Vatanparast J. Persistent alterations in seizure susceptibility, drug responsiveness and comorbidities associated with chemical kindling after neonatal exposure to an organophosphate. Neurotoxicology 2019; 73:92-99. [DOI: 10.1016/j.neuro.2019.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/19/2019] [Accepted: 03/07/2019] [Indexed: 12/20/2022]
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18
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Paternal THC exposure in rats causes long-lasting neurobehavioral effects in the offspring. Neurotoxicol Teratol 2019; 74:106806. [PMID: 31028824 DOI: 10.1016/j.ntt.2019.04.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 04/15/2019] [Accepted: 04/23/2019] [Indexed: 01/09/2023]
Abstract
Developmental neurotoxicity of a wide variety of toxicants mediated via maternal exposure during gestation is very well established. In contrast, the impacts of paternal toxicant exposure on offspring neurobehavioral function are much less well studied. A vector for paternal toxicant exposure on development of his offspring has been identified. Sperm DNA can be imprinted by chemical exposures of the father. Most but not all of the epigenetic marks in sperm are reprogrammed after fertilization. The persisting epigenetic marks can lead to abnormal genetic expression in the offspring. We have found that paternal delta-9-tetrohydrocannabinol (THC) exposure in rats causes changes in methylation of sperm (Murphy et al., 2018). This is similar to cannabis-associated changes in sperm DNA methylation we found in human males who smoke cannabis (Murphy et al., 2018). In the current study we investigated the intergeneration effects of THC exposure of young adult male rats (0 or 2 mg/kg/day orally for 12 days) to the neurobehavioral development of their offspring. This paternal THC exposure was not found to significantly impact the clinical health of the offspring, including litter size, sex ratio, pup birth weight, survival and growth. However, it did cause a long-lasting significant impairment in attentional performance in the offspring relative to controls when they were tested in adulthood. There was also a significant increase in habituation of locomotor activity in the adult offspring of the males exposed to THC prior to mating. This study shows that premating paternal THC exposure even at a modest dose for a brief period can cause deleterious long-term behavioral effects in the offspring, notably significant impairment in an operant attention task. Further research should be conducted to determine the degree to which this type of risk is seen in humans and to investigate the mechanisms underlying these effects and possible treatments to ameliorate these long-term adverse behavioral consequences of paternal THC exposure.
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Bottari NB, Schetinger MRC, Pillat MM, Palma TV, Ulrich H, Alves MS, Morsch VM, Melazzo C, de Barros LD, Garcia JL, Da Silva AS. Resveratrol as a Therapy to Restore Neurogliogenesis of Neural Progenitor Cells Infected by Toxoplasma gondii. Mol Neurobiol 2018; 56:2328-2338. [PMID: 30027338 DOI: 10.1007/s12035-018-1180-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 06/06/2018] [Indexed: 11/25/2022]
Abstract
The intracellular protozoan Toxoplasma gondii may cause congenital toxoplasmosis and serious brain damage in fetus. However, the underlying mechanism of neuropathogenesis in brain toxoplasmosis remains unclear. For this study, neural progenitor cells (NPCs) were obtained from embryo telencephalons (embryonic day 13) and induced to proliferation in the presence of growth factors (GFs). For gathering insights into the biological effects of resveratrol (RSV) on neurogenesis, this study aimed to investigate effects of RSV concentrations (0.1 to 100 μM) on proliferation, migration and differentiation of NPCs infected by T. gondii. T. gondii infection increased the presence of cells in Sub G1 phase, reducing the global frequency of undifferentiated cells in S and G2/M phases of cell cycle and reduced cell viability/mithochondrial activity of infected NPCs. Moreover T. gondii stimulated neural migration and gliogenesis during neutral differentation. However, the treatment with RSV stimulated cell proliferation, restored cellular viability of infected NPCs and exerted an inhibitory effect on gliogenesis of infected NPCs favorecing neuronal maturation during toxoplasmosis infection. Thus, we have successfully to demonstrated that RSV is promising as therapeutic for congenital toxoplasmosis.
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Affiliation(s)
- Nathieli B Bottari
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil
| | - Maria Rosa C Schetinger
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil
| | - Micheli M Pillat
- Department of Biochemistry, Institute of Chemistry, Universidade de São Paulo (USP), São Paulo, SP, Brazil
| | - Thais V Palma
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil
| | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, Universidade de São Paulo (USP), São Paulo, SP, Brazil
| | - Mariana S Alves
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil
| | - Vera M Morsch
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil
| | - Cinthia Melazzo
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil
| | - Luiz Daniel de Barros
- Department of Preventive Veterinary Medicine, Universidade Estadual de Londrina (UEL), Londrina, Paraná, PR, Brazil
| | - João Luis Garcia
- Department of Preventive Veterinary Medicine, Universidade Estadual de Londrina (UEL), Londrina, Paraná, PR, Brazil
| | - Aleksandro Schafer Da Silva
- Graduate Program in Toxicological Biochemical and Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Avenida Roraima, n°1000, Camobi District, Zip Code, Santa Maria, 97105900, Brazil.
- Graduate Program in Animal Science, Universidade do Estado de Santa Catarina (UDESC), Chapecó, SC, Brazil.
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Hagstrom D, Zhang S, Ho A, Tsai ES, Radić Z, Jahromi A, Kaj KJ, He Y, Taylor P, Collins EMS. Planarian cholinesterase: molecular and functional characterization of an evolutionarily ancient enzyme to study organophosphorus pesticide toxicity. Arch Toxicol 2017; 92:1161-1176. [PMID: 29167930 DOI: 10.1007/s00204-017-2130-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 11/15/2017] [Indexed: 12/21/2022]
Abstract
The asexual freshwater planarian Dugesia japonica has emerged as a medium-throughput alternative animal model for neurotoxicology. We have previously shown that D. japonica are sensitive to organophosphorus pesticides (OPs) and characterized the in vitro inhibition profile of planarian cholinesterase (DjChE) activity using irreversible and reversible inhibitors. We found that DjChE has intermediate features of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Here, we identify two candidate genes (Djche1 and Djche2) responsible for DjChE activity. Sequence alignment and structural homology modeling with representative vertebrate AChE and BChE sequences confirmed our structural predictions, and show that both DjChE enzymes have intermediate sized catalytic gorges and disrupted peripheral binding sites. Djche1 and Djche2 were both expressed in the planarian nervous system, as anticipated from previous activity staining, but with distinct expression profiles. To dissect how DjChE inhibition affects planarian behavior, we acutely inhibited DjChE activity by exposing animals to either an OP (diazinon) or carbamate (physostigmine) at 1 µM for 4 days. Both inhibitors delayed the reaction of planarians to heat stress. Simultaneous knockdown of both Djche genes by RNAi similarly resulted in a delayed heat stress response. Furthermore, chemical inhibition of DjChE activity increased the worms' ability to adhere to a substrate. However, increased substrate adhesion was not observed in Djche1/Djche2 (RNAi) animals or in inhibitor-treated day 11 regenerates, suggesting this phenotype may be modulated by other mechanisms besides ChE inhibition. Together, our study characterizes DjChE expression and function, providing the basis for future studies in this system to dissect alternative mechanisms of OP toxicity.
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Affiliation(s)
- Danielle Hagstrom
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Siqi Zhang
- Jacobs School of Engineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Alicia Ho
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Eileen S Tsai
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Zoran Radić
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Aryo Jahromi
- Jacobs School of Engineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Kelson J Kaj
- Department of Physics, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Yingtian He
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Palmer Taylor
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Eva-Maria S Collins
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA. .,Department of Physics, University of California, San Diego, La Jolla, CA, 92093, USA. .,Biology Department, Swarthmore College, Swarthmore, PA, 19081, USA.
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Pallotta MM, Ronca R, Carotenuto R, Porreca I, Turano M, Ambrosino C, Capriglione T. Specific Effects of Chronic Dietary Exposure to Chlorpyrifos on Brain Gene Expression-A Mouse Study. Int J Mol Sci 2017; 18:ijms18112467. [PMID: 29156651 PMCID: PMC5713433 DOI: 10.3390/ijms18112467] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 11/04/2017] [Accepted: 11/07/2017] [Indexed: 01/14/2023] Open
Abstract
Chlorpyrifos (CPF) is an organophosphate insecticide used to control pests on a variety of food and feed crops. In mammals, maternal exposure to CPF has been reported to induce cerebral cortex thinning, alteration of long-term brain cognitive function, and Parkinson-like symptoms, but the mechanisms of these processes are not fully understood. In this study, we aimed to gain a deeper understanding of the alterations induced in the brains of mice chronically exposed to CPF by dietary intake. For our purpose, we analysed F1 offspring (sacrificed at 3 and 8 months) of Mus musculus, treated in utero and postnatally with 3 different doses of CPF (0.1-1-10 mg/kg/day). Using RT2 Profiler PCR Arrays, we evaluated the alterations in the expression of 84 genes associated with neurodegenerative diseases. In the brains of exposed mice, we evidenced a clear dose–response relationship for AChE inhibition and alterations of gene expression. Some of the genes that were steadily down-regulated, such as Pink1, Park 2, Sv2b, Gabbr2, Sept5 and Atxn2, were directly related to Parkinson’s onset. Our experimental results shed light on the possibility that long-term CPF exposure may exert membrane signalling alterations which make brain cells more susceptible to develop neurodegenerative diseases.
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Affiliation(s)
- Maria Michela Pallotta
- Dipartimento di Biologia, Università di Napoli Federico II, Via Cinthia 21, 80126 Napoli, Italy.
| | - Raffaele Ronca
- Dipartimento di Biologia, Università di Napoli Federico II, Via Cinthia 21, 80126 Napoli, Italy.
| | - Rosa Carotenuto
- Dipartimento di Biologia, Università di Napoli Federico II, Via Cinthia 21, 80126 Napoli, Italy.
| | | | - Mimmo Turano
- Dipartimento di Biologia, Università di Napoli Federico II, Via Cinthia 21, 80126 Napoli, Italy.
| | - Concetta Ambrosino
- IRGS, Biogem, Via Camporeale, Ariano Irpino, 83031 Avellino, Italy.
- Dipartimento di Scienze e Tecnologie, Università del Sannio, Via Port'Arsa 11, 82100 Benevento, Italy.
| | - Teresa Capriglione
- Dipartimento di Biologia, Università di Napoli Federico II, Via Cinthia 21, 80126 Napoli, Italy.
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Glazer L, Wells CN, Drastal M, Odamah KA, Galat RE, Behl M, Levin ED. Developmental exposure to low concentrations of two brominated flame retardants, BDE-47 and BDE-99, causes life-long behavioral alterations in zebrafish. Neurotoxicology 2017; 66:221-232. [PMID: 28935585 DOI: 10.1016/j.neuro.2017.09.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/08/2017] [Accepted: 09/17/2017] [Indexed: 11/17/2022]
Abstract
BACKGROUND Polybrominated diphenyl ethers (PBDEs) were widely used as flame retardants until the early 2000s, mainly in home furnishings and electronics. The persistence of PBDEs in the environment leads to continued ubiquitous exposure to low levels, with infants and children experiencing higher exposures than adults. Accumulating evidence suggest that low-level exposures during early life stages can affect brain development and lead to long-term behavioral impairments. We investigated the effects of zebrafish exposure to low doses of the two prominent PBDEs; 2,2',4,4',5,-Pentabromodiphenyl ether (BDE-99) and 2,2',4,4',-Tetrabromodiphenyl ether (BDE-47), during embryo-development on short- and long-term behavioral endpoints. We included the organophosphate pesticide chlorpyrifos (CPF) due to its well documented neurotoxicity across species from zebrafish to humans. METHODS Zebrafish embryos were exposed to the following individual treatments; 0.1% DMSO (vehicle control); 0.3μM CPF; 0.01, 0.03, 0.1, 0.3μM BDE-47; 0.003, 0.03, 0.3, 1, 3, 10, 20μM BDE-99 from 5 until 120h post fertilization (hpf). Low exposure levels were determined as those not causing immediate overt toxicity, and behavior assays were conducted in the low-level range. At 144 hpf the larvae were tested for locomotor activity. At approximately 6 months of age adult zebrafish were tested in a behavioral battery including assays for anxiety-related behavior, sensorimotor response and habituation, social interaction, and predator avoidance. RESULTS In the short-term, larval locomotor activity was reduced in larvae treated with 0.3μM CPF and 0.1μM BDE-47. BDE-99 treatment caused non-monotonic dose effects, with 0.3μM causing hyperactivity and 1μM or higher causing hypoactivity. In the long-term, adult anxiety-related behavior was reduced in all treatments as measured in both the novel tank dive test and tap test. DISCUSSION We show that exposure of zebrafish embryos to low concentrations of the brominated flame retardants BDE-47 and BDE-99, and the organophosphate pesticide CPF, caused both short- and long-term behavioral impairments. Interestingly, we also found that at very low exposure concentrations, where there were no visible effects on larval activity, adult behavior was still strongly affected.
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Affiliation(s)
- Lilah Glazer
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, 27710, USA.
| | - Corinne N Wells
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Meghan Drastal
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Kathryn-Ann Odamah
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Richard E Galat
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Mamta Behl
- National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, 27709, USA
| | - Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, 27710, USA.
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Slotkin TA, Skavicus S, Seidler FJ. Diazinon and parathion diverge in their effects on development of noradrenergic systems. Brain Res Bull 2017; 130:268-273. [PMID: 28235599 DOI: 10.1016/j.brainresbull.2017.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 02/08/2017] [Accepted: 02/10/2017] [Indexed: 10/20/2022]
Abstract
Organophosphate pesticides elicit developmental neurotoxicity through mechanisms over and above their shared property as cholinesterase inhibitors. We compared the consequences of neonatal exposure (postnatal days PN1-4) to diazinon or parathion on development of norepinephrine systems in rat brain, using treatments designed to produce equivalent effects on cholinesterase, straddling the threshold for barely-detectable inhibition. Norepinephrine levels were measured throughout development from the immediate posttreatment period (PN5), to early adolescence (PN30), young adulthood (PN60) and full adulthood (PN100); we assessed multiple brain regions containing all the major noradrenergic synaptic projections. Diazinon elicited a significant overall deficit of norepinephrine, whereas parathion produced a net increase. The effects were not immediately apparent (PN5) but rather emerged over the course of development, indicating that the organophosphate effects represent alteration of the trajectory of development, not just continuance of an initial injury. There were no comparable effects on β-adrenergic receptors, indicating that the presynaptic changes were not an adaptation to an underlying, primary effect on postsynaptic receptor signaling. Because we used the cholinesterase inhibition benchmark, the absolute dose of diazinon was much higher than that of parathion, since the latter is a more potent cholinesterase inhibitor. Our results are consistent with the growing evidence that the various organophosphates can differ in their impact on brain development and that consequently, the cholinesterase benchmark is an inadequate predictor of adverse neurodevelopmental effects.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Samantha Skavicus
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Frederic J Seidler
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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Silva JG, Boareto AC, Schreiber AK, Redivo DDB, Gambeta E, Vergara F, Morais H, Zanoveli JM, Dalsenter PR. Chlorpyrifos induces anxiety-like behavior in offspring rats exposed during pregnancy. Neurosci Lett 2017; 641:94-100. [PMID: 28130185 DOI: 10.1016/j.neulet.2017.01.053] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 01/19/2017] [Accepted: 01/23/2017] [Indexed: 12/27/2022]
Abstract
Chlorpyrifos is a pesticide, member of the organophosphate class, widely used in several countries to manage insect pests on many agricultural crops. Currently, chlorpyrifos health risks are being reevaluated due to possible adverse effects, especially on the central nervous system. The aim of this study was to investigate the possible action of this pesticide on the behaviors related to anxiety and depression of offspring rats exposed during pregnancy. Wistar rats were treated orally with chlorpyrifos (0.01, 0.1, 1 and 10mg/kg/day) on gestational days 14-20. Male offspring behavior was evaluated on post-natal days 21 and 70 by the elevated plus-maze test, open field test and forced swimming test. The results demonstrated that exposure to 0.1, 1 or 10mg/kg/day of chlorpyrifos could induce anxiogenic-like, but not depressive-like behavior at post-natal day 21, without causing fetal toxicity. This effect was reversed on post-natal day 70.
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Affiliation(s)
- Jonas G Silva
- Department of Chemistry and Biology, Federal Technological University of Paraná, Curitiba, Paraná 81280-340, Brazil; Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil.
| | - Ana C Boareto
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Anne K Schreiber
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Daiany D B Redivo
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Eder Gambeta
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Fernanda Vergara
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Helen Morais
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Janaína M Zanoveli
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
| | - Paulo R Dalsenter
- Department of Pharmacology, Federal University of Paraná, Curitiba, Paraná 81540-990 Brazil
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Kwon HJ, Ha M, Kim BN, Lim MH. Harmful Environmental Factors Leading to Attention-Deficit Hyperactivity Disorder. Soa Chongsonyon Chongsin Uihak 2016. [DOI: 10.5765/jkacap.2016.27.4.267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Ho Jang Kwon
- Department of Preventive Medicine, College of Medicine, Dankook University, Cheonan, Korea
- Environmental Health Center, Dankook University Hospital, Cheonan, Korea
| | - Mina Ha
- Department of Preventive Medicine, College of Medicine, Dankook University, Cheonan, Korea
- Environmental Health Center, Dankook University Hospital, Cheonan, Korea
| | - Bung Nyun Kim
- Department of Psychiatry, College of Medicine, Seoul National University, Seoul, Korea
| | - Myung Ho Lim
- Environmental Health Center, Dankook University Hospital, Cheonan, Korea
- Department of Psychology and Psychotherapy, College of Health Science, Dankook University, Cheonan, Korea
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26
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Tussellino M, Ronca R, Carotenuto R, Pallotta MM, Furia M, Capriglione T. Chlorpyrifos exposure affects fgf8, sox9, and bmp4 expression required for cranial neural crest morphogenesis and chondrogenesis in Xenopus laevis embryos. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:630-640. [PMID: 27669663 DOI: 10.1002/em.22057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 09/04/2016] [Indexed: 06/06/2023]
Abstract
Chlorpyrifos (CPF) is an organophosphate insecticide used primarily to control foliage and soil-borne insect pests on a variety of food and feed crops. In mammals, maternal exposure to CPF has been reported to induce dose-related abnormalities such as slower brain growth and cerebral cortex thinning. In lower vertebrates, for example, fish and amphibians, teratogenic activity of this compound is correlated with several anatomical alterations. Little is known about the effects of CPF on mRNA expression of genes involved in early development of the anatomical structures appearing abnormal in embryos. This study investigated the effects of exposure to different CPF concentrations (10, 15 and 20 mg/L) on Xenopus laevis embryos from stage 4/8 to stage 46. Some of the morphological changes we detected in CPF-exposed embryos included cranial neural crest cell (NCC)-derived structures. For this reason, we analyzed the expression of select genes involved in hindbrain patterning (egr2), cranial neural crest chondrogenesis, and craniofacial development (fgf8, bmp4, sox9, hoxa2 and hoxb2). We found that CPF exposure induced a reduction in transcription of all the genes involved in NCC-dependent chondrogenesis, with largest reductions in fgf8 and sox9; whereas, in hindbrain, we did not find any alterations in egr2 expression. Changes in the expression of fgf8, bmp4, and sox9, which are master regulators of several developmental pathways, have important implications. If these changes are confirmed to belong to a general pattern of alterations in vertebrates prenatally exposed to OP, they might be useful to assess damage during vertebrate embryo development. Environ. Mol. Mutagen. 57:589-604, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Margherita Tussellino
- Department of Biology, Università di Napoli "Federico II", Via Cinthia, 21, Napoli, 80126, Italy
| | - Raffaele Ronca
- Department of Biology, Università di Napoli "Federico II", Via Cinthia, 21, Napoli, 80126, Italy
| | - Rosa Carotenuto
- Department of Biology, Università di Napoli "Federico II", Via Cinthia, 21, Napoli, 80126, Italy
| | - Maria M Pallotta
- Department of Biology, Università di Napoli "Federico II", Via Cinthia, 21, Napoli, 80126, Italy
| | - Maria Furia
- Department of Biology, Università di Napoli "Federico II", Via Cinthia, 21, Napoli, 80126, Italy
| | - Teresa Capriglione
- Department of Biology, Università di Napoli "Federico II", Via Cinthia, 21, Napoli, 80126, Italy.
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Decreased anxiety in juvenile rats following exposure to low levels of chlorpyrifos during development. Neurotoxicology 2015; 59:183-190. [PMID: 26642910 DOI: 10.1016/j.neuro.2015.11.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/11/2015] [Accepted: 11/25/2015] [Indexed: 11/22/2022]
Abstract
Exposure to chlorpyrifos (CPF) during the late preweanling period in rats inhibits the endocannabinoid metabolizing enzymes fatty acid hydrolase (FAAH) and monoacylglycerol lipase (MAGL), resulting in accumulation of their respective substrates anandamide (AEA) and 2-arachidonylglycerol (2-AG). This occurs at 1.0mg/kg, but at a lower dosage (0.5mg/kg) only FAAH and AEA are affected with no measurable inhibition of either cholinesterase (ChE) or MAGL. The endocannabinoid system plays a vital role in nervous system development and may be an important developmental target for CPF. The endocannabinoid system plays an important role in the regulation of anxiety and, at higher dosages, developmental exposure to CPF alters anxiety-like behavior. However, it is not clear whether exposure to low dosages of CPF that do not inhibit ChE will cause any persistent effects on anxiety-like behavior. To determine if this occurs, 10-day old rat pups were exposed daily for 7 days to either corn oil or 0.5, 0.75, or 1.0mg/kg CPF by oral gavage. At 12h following the last CPF administration, 1.0mg/kg resulted in significant inhibition of FAAH, MAGL, and ChE, whereas 0.5 and 0.75mg/kg resulted in significant inhibition of only FAAH. AEA levels were significantly elevated in all three treatment groups as were palmitoylethanolamide and oleoylethanolamide, which are also substrates for FAAH. 2-AG levels were significantly elevated by 0.75 and 1.0mg/kg but not 0.5mg/kg. On day 25, the latency to emerge from a dark container into a highly illuminated novel open field was measured as an indicator of anxiety. All three CPF treatment groups spent significantly less time in the dark container prior to emerging as compared to the control group, suggesting a decreased level of anxiety. This demonstrates that repeated preweanling exposure to dosages of CPF that do not inhibit brain ChE can induce a decline in the level of anxiety that is detectable during the early postweanling period.
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Mundy WR, Padilla S, Breier JM, Crofton KM, Gilbert ME, Herr DW, Jensen KF, Radio NM, Raffaele KC, Schumacher K, Shafer TJ, Cowden J. Expanding the test set: Chemicals with potential to disrupt mammalian brain development. Neurotoxicol Teratol 2015; 52:25-35. [PMID: 26476195 DOI: 10.1016/j.ntt.2015.10.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/02/2015] [Accepted: 10/04/2015] [Indexed: 11/15/2022]
Abstract
High-throughput test methods including molecular, cellular, and alternative species-based assays that examine critical events of normal brain development are being developed for detection of developmental neurotoxicants. As new assays are developed, a "training set" of chemicals is used to evaluate the relevance of individual assays for specific endpoints. Different training sets are necessary for each assay that would comprise a developmental neurotoxicity test battery. In contrast, evaluation of the predictive ability of a comprehensive test battery requires a set of chemicals that have been shown to alter brain development after in vivo exposure ("test set"). Because only a small number of substances have been well documented to alter human neurodevelopment, we have proposed an expanded test set that includes chemicals demonstrated to adversely affect neurodevelopment in animals. To compile a list of potential developmental neurotoxicants, a literature review of compounds that have been examined for effects on the developing nervous system was conducted. The search was limited to mammalian studies published in the peer-reviewed literature and regulatory studies submitted to the U.S. EPA. The definition of developmental neurotoxicity encompassed changes in behavior, brain morphology, and neurochemistry after gestational or lactational exposure. Reports that indicated developmental neurotoxicity was observed only at doses that resulted in significant maternal toxicity or were lethal to the fetus or offspring were not considered. As a basic indication of reproducibility, we only included a chemical if data on its developmental neurotoxicity were available from more than one laboratory (defined as studies originating from laboratories with a different senior investigator). Evidence from human studies was included when available. Approximately 100 developmental neurotoxicity test set chemicals were identified, with 22% having evidence in humans.
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Affiliation(s)
- William R Mundy
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.
| | - Stephanie Padilla
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Joseph M Breier
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Kevin M Crofton
- National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Mary E Gilbert
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - David W Herr
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Karl F Jensen
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Nicholas M Radio
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Kathleen C Raffaele
- Office of Solid Waste and Emergency Response, U.S. Environmental Protection Agency, Washington, DC, USA
| | | | - Timothy J Shafer
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - John Cowden
- National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
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Developmental exposure to organophosphate flame retardants causes behavioral effects in larval and adult zebrafish. Neurotoxicol Teratol 2015; 52:220-7. [PMID: 26344674 DOI: 10.1016/j.ntt.2015.08.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 08/31/2015] [Accepted: 08/31/2015] [Indexed: 11/24/2022]
Abstract
BACKGROUND Organophosphate flame retardants (OPFRs) have grown in usage since concerns about the health effects of the previously used polybrominated flame retardants led to their being phased out. The potential for OPFRs to cause adverse health effects of their own is still unexamined. Because of their structural similarities to organophosphate pesticides, which have themselves been heavily researched and shown to be neurobehavioral teratogens, we investigated the possibility that developmental exposure to two OPFRs, triphenyl phosphate (TPHP), and tris(1,3-dichloroisopropyl)phosphate (TDCIPP) might lead to behavioral impairment across the lifespan, as has been observed with the organophosphate pesticide chlorpyrifos. METHODS Zebrafish were exposed to 0.03 or 0.3 μM of TPHP, TDCIPP, or chlorpyrifos from 0 to 5 days post fertilization. Vehicle control consisted of 0.03% solution of DMSO. At 6 days post fertilization, larvae were tested on a locomotor assay. Separate cohorts of 6 day old larvae that were not tested on the larval assay were allowed to grow to adulthood. At 12 weeks post fertilization, these adult zebrafish were tested on a battery of behavioral assays that included tests of novel environment exploration, startle habituation, social affiliation, and predator escape. RESULTS Developmental exposure altered zebrafish behavior across the lifespan. Larval zebrafish exposed to the 0.03 μM doses of chlorpyrifos or TDCIPP exhibited significant (p<0.05) hyperactivity in the locomotor assay. Organophosphate exposure significantly (p<0.05) altered the time course of adult zebrafish behavior in the novel environment, startle habituation, and social affiliation assays. Predator escape behavior was significantly (p<0.05) reduced in fish exposed to the 0.3 μM dose of TDCIPP. Exposure also caused hyperactivity in adult fish, with fish exposed to the 0.3 μM dose of TDCIPP exhibiting significantly (p<0.05) elevated locomotor behavior in the novel environment assay. DISCUSSION Early developmental exposure to OPFRs produced behavioral impairment that persisted into adulthood. These findings support broader research investigating the role of organophosphate compounds, including the OPFRs used here, in developmental neurotoxicity.
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Lipopolysaccharide Exposure Induces Maternal Hypozincemia, and Prenatal Zinc Treatment Prevents Autistic-Like Behaviors and Disturbances in the Striatal Dopaminergic and mTOR Systems of Offspring. PLoS One 2015. [PMID: 26218250 PMCID: PMC4517817 DOI: 10.1371/journal.pone.0134565] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Autism is characterized by social deficits, repetitive behaviors, and cognitive inflexibility. The risk factors appear to include genetic and environmental conditions, such as prenatal infections and maternal dietary factors. Previous investigations by our group have demonstrated that prenatal exposure to lipopolysaccharide (LPS), which mimics infection by gram-negative bacteria, induces autistic-like behaviors. To understand the causes of autistic-like behaviors, we evaluated maternal serum metal concentrations, which are involved in intrauterine development and infection/inflammation. We identified reduced maternal levels of zinc, magnesium, selenium and manganese after LPS exposure. Because LPS induced maternal hypozincemia, we treated dams with zinc in an attempt to prevent or ease the impairments in the offspring. We evaluated the social and cognitive autistic-like behaviors and brain tissues of the offspring to identify the central mechanism that triggers the development of autism. Prenatal LPS exposure impaired play behaviors and T-maze spontaneous alternations, i.e., it induced autistic-like behaviors. Prenatal LPS also decreased tyrosine hydroxylase levels and increased the levels of mammalian target of rapamycin (mTOR) in the striatum. Thus, striatal dopaminergic impairments may be related to autism. Moreover, excessive signaling through the mTOR pathway has been considered a biomarker of autism, corroborating our rat model of autism. Prenatal zinc treatment prevented these autistic-like behaviors and striatal dopaminergic and mTOR disturbances in the offspring induced by LPS exposure. The present findings revealed a possible relation between maternal hypozincemia during gestation and the onset of autism. Furthermore, prenatal zinc administration appears to have a beneficial effect on the prevention of autism.
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Slotkin TA, Skavicus S, Levin ED, Seidler FJ. Prenatal nicotine changes the response to postnatal chlorpyrifos: Interactions targeting serotonergic synaptic function and cognition. Brain Res Bull 2015; 111:84-96. [PMID: 25592617 DOI: 10.1016/j.brainresbull.2015.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 12/29/2014] [Accepted: 01/05/2015] [Indexed: 11/25/2022]
Abstract
Nicotine and chlorpyrifos are developmental neurotoxicants that target serotonin systems. We examined whether prenatal nicotine exposure alters the subsequent response to chlorpyrifos given postnatally. Pregnant rats received nicotine throughout gestation at 3mg/kg/day, a regimen designed to achieve plasma levels seen in smokers; chlorpyrifos was given to pups on postnatal days (PN) 1-4 at 1mg/kg, just above the detection threshold for brain cholinesterase inhibition. We assessed long-term effects from adolescence (PN30) through full adulthood (PN150), measuring the expression of serotonin receptors and serotonin turnover (index of presynaptic impulse activity) in cerebrocortical brain regions encompassing the projections that are known targets for nicotine and chlorpyrifos. Nicotine or chlorpyrifos individually increased the expression of serotonin receptors, with greater effects on males than on females and with distinct temporal and regional patterns indicative of adaptive synaptic changes rather than simply an extension of initial injury. This interpretation was confirmed by our finding an increase in serotonin turnover, connoting presynaptic serotonergic hyperactivity. Animals receiving the combined treatment showed a reduction in these adaptive effects on receptor binding and turnover relative to the individual agents, or even an effect in the opposite direction; further, normal sex differences in serotonin receptor concentrations were dissipated or reversed, an effect that was confirmed by behavioral evaluations in the Novel Objection Recognition Test. In addition to the known liabilities associated with maternal smoking during pregnancy, our results point to additional costs in the form of heightened vulnerability to neurotoxic chemicals encountered later in life.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Samantha Skavicus
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Edward D Levin
- Department of Psychiatry & Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA
| | - Frederic J Seidler
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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Peris-Sampedro F, Salazar JG, Cabré M, Reverte I, Domingo JL, Sánchez-Santed F, Colomina MT. Impaired retention in AβPP Swedish mice six months after oral exposure to chlorpyrifos. Food Chem Toxicol 2014; 72:289-94. [DOI: 10.1016/j.fct.2014.07.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/22/2014] [Accepted: 07/28/2014] [Indexed: 02/07/2023]
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Assessment of attention and inhibitory control in rodent developmental neurotoxicity studies. Neurotoxicol Teratol 2014; 52:78-87. [PMID: 25224214 DOI: 10.1016/j.ntt.2014.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 08/16/2014] [Accepted: 09/05/2014] [Indexed: 11/20/2022]
Abstract
In designing screens to assess potential neurotoxicants, the paramount goal is that the selected assessment tools detect dysfunction if it exists. This goal is particularly challenging in the case of cognitive assessments. Cognition is not a unitary phenomenon, and indeed there is growing evidence that different aspects of cognitive functioning are subserved by distinct neural systems. As a result, if a particular neurotoxicant selectively damages certain neural systems but not others, it can impair some cognitive, sensory, or affective functions, but leave many others intact. Accordingly, studies with human subjects use batteries of cognitive tests, cognizant of the fact that no one test is capable of detecting all forms of cognitive dysfunction. In contrast, assessment of cognitive functioning in non-human animal developmental neurotoxicity (DNT) studies typically consists of a single, presumably representative, "learning and memory" task that is expected to detect all potential effects on cognitive functioning. Streamlining the cognitive assessment in these studies saves time and money, but these shortcuts can have serious consequences if the aspect of cognitive functioning that is impaired is not tapped by the single selected task. In particular, executive functioning - a constellation of cognitive functions which enables the organism to focus on multiple streams of information simultaneously, and revise plans as necessary - is poorly assessed in most animal DNT studies. The failure to adequately assess these functions - which include attention, working memory, inhibitory control, and planning - is particularly worrisome in light of evidence that the neural systems that subserve these functions may be uniquely vulnerable to early developmental insults. We illustrate the importance of tapping these areas of functioning in DNT studies by describing the pattern of effects produced by early developmental Pb exposure. Rats exposed to lead (Pb) early in development were tested on a series of automated attention tasks, as well as on a radial arm maze task. The lead-exposed rats were not impaired in this demanding radial arm maze task, despite conditions which tapped the limits of both working and long-term memory. In contrast, the automated tests designed to assess rodent executive functioning revealed selective and functionally important deficits in attention and regulation of emotion or negative affect (produced by committing an error or not receiving an expected reward). This example underscores the importance of including tasks to specifically tap executive functioning in DNT batteries. Such tasks are not only sensitive but can also shed light on the specific nature of the dysfunction, and they can implicate dysfunction of specific neural systems, information which can be used to design therapeutic interventions. Although the use of such tasks increases the time and effort needed to complete the battery, the benefits outweigh the cost, in light of the greater sensitivity of the battery and the more complete characterization of effects.
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Deshpande LS, Phillips K, Huang B, DeLorenzo RJ. Chronic behavioral and cognitive deficits in a rat survival model of paraoxon toxicity. Neurotoxicology 2014; 44:352-7. [PMID: 25172410 DOI: 10.1016/j.neuro.2014.08.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/07/2014] [Accepted: 08/08/2014] [Indexed: 01/15/2023]
Abstract
Organophosphate (OP) compounds, including paraoxon (POX), are similar to nerve agents such as sarin. There is a growing concern that OP agents could be weaponized to cause mass civilian causalities. We have developed a rodent survival model of POX toxicity that is being used to evaluate chronic morbidity and to screen for medical countermeasures against severe OP exposure. It is well known that the survivors of nerve gas and chronic OP exposure exhibit neurobehavioral deficits such as mood changes, depression, and memory impairments. In this study we investigated whether animals surviving severe POX exposure exhibited long-term neurological impairments. POX exposure produced overt signs of cholinergic toxicity. Rats were rescued using an optimized atropine, 2-PAM and diazepam therapy. Surviving rats were studied using established behavioral assays for identifying symptoms of depression and memory impairment 3-months after POX exposure. In the forced swim test, POX rats exhibited increased immobility time indicative of a despair-like state. In the sucrose preference test, POX rats consumed significantly less sucrose water indicating anhedonia-like condition. POX rats also displayed increased anxiety as characterized by significantly lower performance in the open arm of the elevated plus maze. Further, when tested with a novel object recognition paradigm, POX rats exhibited a negative discrimination ratio indicative of impaired recognition memory. The results indicate that this model of survival from severe POX exposure can be employed to study some of the molecular bases for OP-induced chronic behavioral and cognitive comorbidities and develop therapies for their treatment.
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Affiliation(s)
| | - Kristin Phillips
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Beverly Huang
- Department of Neuroscience, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Robert J DeLorenzo
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA; Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA; Department of Molecular Biophysics and Biochemistry, Virginia Commonwealth University, Richmond, VA 23298, USA.
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Carr RL, Graves CA, Mangum LC, Nail CA, Ross MK. Low level chlorpyrifos exposure increases anandamide accumulation in juvenile rat brain in the absence of brain cholinesterase inhibition. Neurotoxicology 2013; 43:82-89. [PMID: 24373905 DOI: 10.1016/j.neuro.2013.12.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 12/18/2013] [Accepted: 12/19/2013] [Indexed: 12/15/2022]
Abstract
The prevailing dogma is that chlorpyrifos (CPF) mediates its toxicity through inhibition of cholinesterase (ChE). However, in recent years, the toxicological effects of developmental CPF exposure have been attributed to an unknown non-cholinergic mechanism of action. We hypothesize that the endocannabinoid system may be an important target because of its vital role in nervous system development. We have previously reported that repeated exposure to CPF results in greater inhibition of fatty acid amide hydrolase (FAAH), the enzyme that metabolizes the endocannabinoid anandamide (AEA), than inhibition of either forebrain ChE or monoacylglycerol lipase (MAGL), the enzyme that metabolizes the endocannabinoid 2-arachidonylglycerol (2-AG). This exposure resulted in the accumulation of 2-AG and AEA in the forebrain of juvenile rats; however, even at the lowest dosage level used (1.0mg/kg), forebrain ChE inhibition was still present. Thus, it is not clear if FAAH activity would be inhibited at dosage levels that do not inhibit ChE. To determine this, 10 day old rat pups were exposed daily for 7 days to either corn oil or 0.5mg/kg CPF by oral gavage. At 4 and 12h post-exposure on the last day of administration, the activities of serum ChE and carboxylesterase (CES) and forebrain ChE, MAGL, and FAAH were determined as well as the forebrain AEA and 2-AG levels. Significant inhibition of serum ChE and CES was present at both 4 and 12h. There was no significant inhibition of the activities of forebrain ChE or MAGL and no significant change in the amount of 2-AG at either time point. On the other hand, while no statistically significant effects were observed at 4h, FAAH activity was significantly inhibited at 12h resulting in a significant accumulation of AEA. Although it is not clear if this level of accumulation impacts brain maturation, this study demonstrates that developmental CPF exposure at a level that does not inhibit brain ChE can alter components of endocannabinoid signaling.
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Affiliation(s)
- Russell L Carr
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Casey A Graves
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Lee C Mangum
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Carole A Nail
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Matthew K Ross
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
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Allen EMG, Florang VR, Davenport LL, Jinsmaa Y, Doorn JA. Cellular localization of dieldrin and structure-activity relationship of dieldrin analogues in dopaminergic cells. Chem Res Toxicol 2013; 26:1043-54. [PMID: 23763672 DOI: 10.1021/tx300458b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The incidence of Parkinson's disease (PD) correlates with environmental exposure to pesticides, such as the organochlorine insecticide, dieldrin. Previous studies found an increased concentration of the pesticide in the striatal region of the brains of PD patients and also that dieldrin adversely affects cellular processes associated with PD. These processes include mitochondrial function and reactive oxygen species production. However, the mechanism and specific cellular targets responsible for dieldrin-mediated cellular dysfunction and the structural components of dieldrin contributing to its toxicity (toxicophore) have not been fully defined. In order to identify the toxicophore of dieldrin, a structure-activity approach was used, with the toxicity profiles of numerous analogues of dieldrin (including aldrin, endrin, and cis-aldrin diol) assessed in PC6-3 cells. The MTT and lactate dehydrogenase (LDH) assays were used to monitor cell viability and membrane permeability after treatment with each compound. Cellular assays monitoring ROS production and extracellular dopamine metabolite levels were also used. Structure and stereochemistry for dieldrin were found to be very important for toxicity and other end points measured. Small changes in structure for dieldrin (e.g., comparison to the stereoisomer endrin) yielded significant differences in toxicity. Interestingly, the cis-diol metabolite of dieldrin was found to be significantly more toxic than the parent compound. Disruption of dopamine catabolism yielded elevated levels of the neurotoxin, 3,4-dihydroxyphenylacetaldehyde, for many organochlorines. Comparisons of the toxicity profiles for each dieldrin analogue indicated a structure-specific effect important for elucidating the mechanisms of dieldrin neurotoxicity.
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Affiliation(s)
- Erin M G Allen
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, The University of Iowa , Iowa City, Iowa 52242, United States
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Carr RL, Adams AL, Kepler DR, Ward AB, Ross MK. Induction of endocannabinoid levels in juvenile rat brain following developmental chlorpyrifos exposure. Toxicol Sci 2013; 135:193-201. [PMID: 23761300 DOI: 10.1093/toxsci/kft126] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The endogenous cannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA) play vital roles during nervous system development. The degradation of 2-AG and AEA is mediated by monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), respectively. These enzymes are inhibited following developmental chlorpyrifos (CPF) exposure. To investigate whether this inhibition is persistent or whether accumulation of endocannabinoids in the brain occurs, 10-day-old rat pups were orally exposed daily for 7 days to either corn oil or increasing dosages of CPF (1, 2.5, or 5mg/kg), and forebrains were collected at 4, 12, 24, and 48h following the last administration. All dosages inhibited cholinesterase (ChE), FAAH, and MAGL, and elevated AEA and 2-AG levels with the greatest effect occurring at 12h with ChE, FAAH, AEA, and 2-AG and at 4h with MAGL. With the high dosage, return to control levels occurred with 2-AG (48h) only. With the medium dosage, return to control levels occurred with MAGL, 2-AG, and AEA (48h) but not with ChE or FAAH. With the low dosage, return to control levels occurred with MAGL (12h), ChE and 2-AG (24h), and AEA (48h) but not with FAAH. With the lowest dosage, peak inhibition of FAAH (52%) is greater than that of ChE (24%) and that level of FAAH inhibition is sufficient to induce a persistent pattern of elevated AEA. It is possible that this pattern of elevation could alter the appropriate development of neuronal brain circuits.
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Affiliation(s)
- Russell L Carr
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi 39762-6100, USA.
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Lima CS, Dutra-Tavares AC, Nunes F, Nunes-Freitas AL, Ribeiro-Carvalho A, Filgueiras CC, Manhães AC, Meyer A, Abreu-Villaça Y. Methamidophos exposure during the early postnatal period of mice: immediate and late-emergent effects on the cholinergic and serotonergic systems and behavior. Toxicol Sci 2013; 134:125-39. [PMID: 23596261 DOI: 10.1093/toxsci/kft095] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Organophosphates (OPs) are among the most used pesticides. Although some OPs have had their use progressively more restricted, other OPs are being used without sufficient investigation of their effects. Here, we investigated the immediate neurochemical and delayed neurochemical and behavioral actions of the OP methamidophos to verify whether there are concerns regarding exposure during early postnatal development. From the third to the nineth postnatal day (PN), Swiss mice were sc injected with methamidophos (1mg/kg). At PN10, we assessed cholinergic and serotonergic biomarkers in the cerebral cortex and brainstem. From PN60 to PN63, mice were submitted to a battery of behavioral tests and subsequently to biochemical analyses. At PN10, the effects were restricted to females and to the cholinergic system: Methamidophos promoted increased choline transporter binding in the brainstem. At PN63, in the brainstem, there was a decrease in choline transporter, a female-only decrease in 5HT1A and a male-only increase in 5HT2 receptor binding. In the cortex, choline acetyltransferase activity was decreased and 5HT2 receptor binding was increased both in males and females. Methamidophos elicited behavioral alterations, suggestive of increased depressive-like behavior and impaired decision making. There were no significant alterations on anxiety-related measures and on memory/learning. Methamidophos elicited cholinergic and serotonergic alterations that depended on brain region, sex, and age of the animals. These outcomes, together with the behavioral effects, indicate that this OP is deleterious to the developing brain and that alterations are indeed identified long after the end of exposure.
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Affiliation(s)
- Carla S Lima
- Departamento de Ciências Fisiológicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
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Review of current evidence on the impact of pesticides, polychlorinated biphenyls and selected metals on attention deficit / hyperactivity disorder in children. Int J Occup Med Environ Health 2013; 26:16-38. [PMID: 23526196 DOI: 10.2478/s13382-013-0073-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 07/19/2012] [Indexed: 11/20/2022] Open
Abstract
The aim of this review was to investigate the association between attention deficit / hyperactivity disorder (ADHD) or ADHD-related symptoms and industrial chemicals, such as organophosphates and organochlorine pesticides, polychlorinated biphenyls (PCBs), lead, mercury and manganese. Medline, PubMed and EBSCO searches were performed to identify the studies that analyzed the association of prenatal and postnatal child exposure to such toxicants and ADHD or ADHD-related symptoms. The review is restricted to human studies published in English in peer-reviewed journals since 2000. Most of the presented studies focused on pesticides, PCB and lead. The impact of mercury and manganese was investigated less frequently. The findings indicate that children's exposure to organophosphate pesticides may cause symptoms consistent with pervasive developmental disorder, ADHD or attention problems. Exposures to organochlorine pesticides and PCBs were associated with ADHD-like behaviors such as alertness, quality of alert response, and cost of attention. The studies provided evidence that blood lead level below 10 μg/dl was associated with ADHD or ADHD-related symptoms. Information on the association between exposure to mercury and neurotoxicity is limited, and requires further confirmation in future research. Two studies indicated that exposure to manganese is related to ADHD; such exposure and its impact on children neurodevelopment need to be further investigated. Future studies should use a prospective design with multiple biological samples collected over time for better assessment of exposure and its critical windows. Additionally, inclusion of potential confounding factors and co-exposures is crucial.
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Burns CJ, McIntosh LJ, Mink PJ, Jurek AM, Li AA. Pesticide exposure and neurodevelopmental outcomes: review of the epidemiologic and animal studies. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2013; 16:127-283. [PMID: 23777200 PMCID: PMC3705499 DOI: 10.1080/10937404.2013.783383] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Assessment of whether pesticide exposure is associated with neurodevelopmental outcomes in children can best be addressed with a systematic review of both the human and animal peer-reviewed literature. This review analyzed epidemiologic studies testing the hypothesis that exposure to pesticides during pregnancy and/or early childhood is associated with neurodevelopmental outcomes in children. Studies that directly queried pesticide exposure (e.g., via questionnaire or interview) or measured pesticide or metabolite levels in biological specimens from study participants (e.g., blood, urine, etc.) or their immediate environment (e.g., personal air monitoring, home dust samples, etc.) were eligible for inclusion. Consistency, strength of association, and dose response were key elements of the framework utilized for evaluating epidemiologic studies. As a whole, the epidemiologic studies did not strongly implicate any particular pesticide as being causally related to adverse neurodevelopmental outcomes in infants and children. A few associations were unique for a health outcome and specific pesticide, and alternative hypotheses could not be ruled out. Our survey of the in vivo peer-reviewed published mammalian literature focused on effects of the specific active ingredient of pesticides on functional neurodevelopmental endpoints (i.e., behavior, neuropharmacology and neuropathology). In most cases, effects were noted at dose levels within the same order of magnitude or higher compared to the point of departure used for chronic risk assessments in the United States. Thus, although the published animal studies may have characterized potential neurodevelopmental outcomes using endpoints not required by guideline studies, the effects were generally observed at or above effect levels measured in repeated-dose toxicology studies submitted to the U.S. Environmental Protection Agency (EPA). Suggestions for improved exposure assessment in epidemiology studies and more effective and tiered approaches in animal testing are discussed.
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Affiliation(s)
| | | | - Pamela J. Mink
- Allina Health Center for Healthcare Research & Innovation, Minneapolis, Minnesota, USA
| | - Anne M. Jurek
- Allina Health Center for Healthcare Research & Innovation, Minneapolis, Minnesota, USA
| | - Abby A. Li
- Exponent, Inc., Menlo Park, California, USA
- Address correspondence to Abby A. Li, PhD, Attn: Rebecca Edwards, Exponent, Inc., Health Sciences Group, 149 Commonwealth Drive, Menlo Park, CA 94025-1133, USA. E-mail:
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Impairment of novel object recognition in adulthood after neonatal exposure to diazinon. Arch Toxicol 2012; 87:753-62. [PMID: 23212306 DOI: 10.1007/s00204-012-0989-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 11/21/2012] [Indexed: 01/04/2023]
Abstract
Diazinon is an organophosphate pesticide that is still heavily used in agriculture, home gardening, and indoor pest control in Japan. The present study investigated the effect of neonatal exposure to diazinon on hippocampus-dependent novel object recognition test performance and the expression of the N-methyl-D-aspartate (NMDA) receptor and its signal transduction pathway-related genes in the hippocampi of young adult and adult mice. Male offspring of C3H/HeN mice were subcutaneously treated with 0, 0.5, or 5 mg/kg of diazinon for 4 consecutive days beginning on postnatal day (PND) 8. Beginning on PND 46 or PND 81, a novel object recognition test was performed on 4 consecutive days. The hippocampi were collected on PND 50 or PND 85 after the completion of the novel object recognition test, and the expression levels of neurotrophins and the NMDA receptor and its signal transduction pathway-related genes were examined using real-time RT-PCR. Diazinon-injected mice exhibited a poor ability to discriminate between novel and familiar objects during both the PND 49 and the PND 84 tests. The NMDA receptor subunits NR1 and NR2B and the related protein kinase calcium/calmodulin-dependent protein kinase (CaMK)-IV and the transcription factor cyclic AMP responsive element binding protein (CREB)-1 mRNA levels were reduced in the PND 50 mice. However, no significant changes in the expressions of the NMDA subunits and their signal transduction molecules were observed in the hippocampi of the PND 85 mice. The expression level of nerve growth factor mRNA was significantly reduced in the PND 50 or 85 mice. These results indicate that neonatal diazinon exposure impaired the hippocampus-dependent novel object recognition ability, accompanied by a modulation in the expressions of the NMDA receptor and neurotrophin in young adult and adult mice.
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Vandenberg LN, Colborn T, Hayes TB, Heindel JJ, Jacobs DR, Lee DH, Shioda T, Soto AM, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev 2012; 33:378-455. [PMID: 22419778 PMCID: PMC3365860 DOI: 10.1210/er.2011-1050] [Citation(s) in RCA: 1986] [Impact Index Per Article: 165.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/07/2012] [Indexed: 02/08/2023]
Abstract
For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.
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Affiliation(s)
- Laura N Vandenberg
- Tufts University, Center for Regenerative and Developmental Biology, Department of Biology, 200 Boston Avenue, Suite 4600, Medford, Massachusetts 02155, USA.
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Cole TB, Fisher JC, Burbacher TM, Costa LG, Furlong CE. Neurobehavioral assessment of mice following repeated postnatal exposure to chlorpyrifos-oxon. Neurotoxicol Teratol 2012; 34:311-22. [PMID: 22425525 PMCID: PMC3367041 DOI: 10.1016/j.ntt.2012.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 02/08/2012] [Accepted: 02/29/2012] [Indexed: 11/17/2022]
Abstract
Chlorpyrifos (CPF), one of the most widely-used organophosphorus (OP) insecticides in agriculture, is degraded in the field to its oxon form, chlorpyrifos-oxon (CPO), which can represent a significant contaminant in exposures to adults and children. CPO is also responsible for the acetylcholinesterase (AChE) inhibition associated with CPF exposures; CPF is converted by liver CYP450 enzymes to CPO, which binds to and inhibits AChE and other serine active-site esterases, lipases and proteases. Young children represent a particularly susceptible population for exposure to CPF and CPO, in part because levels of the plasma enzyme, paraoxonase (PON1), which hydrolyzes CPO, are very low during early development. While a number of studies have demonstrated developmental neurotoxicity associated with CPF exposure, including effects at or below the threshold levels for AChE inhibition, it is unclear whether these effects were due directly to CPF or to its active metabolite, CPO. PON1 knockout (PON1-/-) mice, which lack PON1, represent a highly sensitive mouse model for toxicity associated with exposure to CPF or CPO. To examine the neurobehavioral consequences of CPO exposure during postnatal development, PON1-/- mice were exposed daily from PND 4 to PND 21 to CPO at 0.15, 0.18, or 0.25 mg/kg/d. A neurobehavioral test battery did not reveal significant effects of CPO on early reflex development, motor coordination, pre-pulse inhibition of startle, startle amplitude, open field behavior, or learning and memory in the contextual fear conditioning, Morris water maze, or water radial-arm maze tests. However, body weight gain and startle latency were significantly affected by exposure to 0.25 mg/kg/d CPO. Additionally, from PNDs 15-20 the mice exposed repeatedly to CPO at all three doses exhibited a dose-related transient hyperkinesis in the 20-min period following CPO administration, suggesting possible effects on catecholaminergic neurotransmission. Our previous study demonstrated wide-ranging effects of neonatal CPO exposure on gene expression in the brain and on brain AChE inhibition, and modulation of both of these effects by the PON1(Q192R) polymorphism. The current study indicates that the neurobehavioral consequences of these effects are more elusive, and suggests that alternative neurobehavioral tests might be warranted, such as tests of social interactions, age-dependent effects on learning and memory, or tests designed specifically to assess dopaminergic or noradrenergic function.
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Affiliation(s)
- Toby B. Cole
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, United States
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
- Department of Genome Sciences, University of Washington, Seattle, WA, United States
| | - Jenna C. Fisher
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, United States
| | - Thomas M. Burbacher
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, United States
| | - Lucio G. Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, United States
| | - Clement E. Furlong
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
- Department of Genome Sciences, University of Washington, Seattle, WA, United States
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London L, Beseler C, Bouchard MF, Bellinger DC, Colosio C, Grandjean P, Harari R, Kootbodien T, Kromhout H, Little F, Meijster T, Moretto A, Rohlman DS, Stallones L. Neurobehavioral and neurodevelopmental effects of pesticide exposures. Neurotoxicology 2012; 33:887-96. [PMID: 22269431 DOI: 10.1016/j.neuro.2012.01.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 01/06/2012] [Accepted: 01/09/2012] [Indexed: 11/28/2022]
Abstract
The association between pesticide exposure and neurobehavioral and neurodevelopmental effects is an area of increasing concern. This symposium brought together participants to explore the neurotoxic effects of pesticides across the lifespan. Endpoints examined included neurobehavioral, affective and neurodevelopmental outcomes among occupational (both adolescent and adult workers) and non-occupational populations (children). The symposium discussion highlighted many challenges for researchers concerned with the prevention of neurotoxic illness due to pesticides and generated a number of directions for further research and policy interventions for the protection of human health, highlighting the importance of examining potential long-term effects across the lifespan arising from early adolescent, childhood or prenatal exposure.
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Affiliation(s)
- Leslie London
- Centre for Occupational and Environmetal Health Research, School of Public Health and Family Medicine, University of Cape Town, South Africa
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Lin T, Duek O, Dori A, Kofman O. Differential long term effects of early diisopropylfluorophosphate exposure in Balb/C and C57Bl/J6 mice. Int J Dev Neurosci 2011; 30:113-20. [PMID: 22197972 DOI: 10.1016/j.ijdevneu.2011.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 12/01/2011] [Accepted: 12/08/2011] [Indexed: 11/17/2022] Open
Abstract
The long-term effect of postnatal administration of a sub-toxic dose of the irreversible acetylcholinesterase inhibitor diisopropylfluorophosphate (DFP) on depression and anxiety behavior was compared in two strains of inbred mice. C57BL/6J and Balb/C mice were injected for 7 consecutive days with either 1 mg/kg DFP or saline on postnatal days 14-20. Mice were tested at age 3-4 months for initial and learned anxiety using double-exposure elevated plus maze and to a novel enclosed environment. Depression was assayed using the sweet preference model of anhedonia and the forced swim test for despair. Postnatal DFP pretreatment led to less activity and more immobility in the elevated plus maze in both mouse strains in the first session. The effect was attenuated in the second session in the C57BL/6J strain but not the Balb/C strain. DFP did not affect the sweet preference or forced swim tests, suggesting a dissociation between the long-term effects of DFP on immobility in the context of approach-avoidance conflict (elevated plus maze) versus despair (forced swim).
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Affiliation(s)
- Tamar Lin
- Department of Psychology and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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46
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Moore PD, Patlolla AK, Tchounwou PB. Cytogenetic evaluation of malathion-induced toxicity in Sprague-Dawley rats. Mutat Res 2011; 725:78-82. [PMID: 21835262 DOI: 10.1016/j.mrgentox.2011.07.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 07/10/2011] [Accepted: 07/14/2011] [Indexed: 11/30/2022]
Abstract
Malathion is a well known pesticide and is commonly used in many agricultural and non-agricultural settings. Its toxicity has been attributed primarily to the accumulation of acetylcholine (Ach) at nerve junctions, due to the inhibition of acetylcholinesterase (AChE), and consequently overstimulation of the nicotinic and muscarinic receptors. However, the genotoxicity of malathion has not been adequately studied; published studies suggest a weak interaction with the genetic material. In the present study, we investigated the genotoxic potential of malathion in bone marrow cells and peripheral blood obtained from Sprague-Dawley rats using chromosomal aberrations (CAs), mitotic index (MI), and DNA damage as toxicological endpoints. Four groups of four male rats, each weighing approximately 60 ± 2g, were injected intraperitoneally (i.p.) once a day for five days with doses of 2.5, 5, 10, and 20mg/kg body weight (BW) of malathion dissolved in 1% DMSO. The control group was made up of four animals injected with 1% DMSO. All the animals were sacrificed 24h after the fifth day treatment. Chromosome preparations were obtained from bone marrow cells following standard protocols. DNA damage in peripheral blood leukocytes was determined using alkaline single-cell gel electrophoresis (comet assay). Malathion exposure significantly increased the number of structural chromosomal aberrations (CAs) and the percentages of DNA damage, and decreased the mitotic index (MI) in treated groups when compared with the control group. Our results demonstrate that malathion has a clastogenic/genotoxic potential as measured by the bone marrow CA and comet assay in Sprague-Dawley rats.
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Affiliation(s)
- Pamela D Moore
- Molecular Toxicology Research Laboratory, NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, 1400 Lynch Street, Box 18540, Jackson, MS 39217, USA
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Critical duration of exposure for developmental chlorpyrifos-induced neurobehavioral toxicity. Neurotoxicol Teratol 2011; 33:742-51. [PMID: 21745564 DOI: 10.1016/j.ntt.2011.06.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/15/2011] [Accepted: 06/28/2011] [Indexed: 11/20/2022]
Abstract
Developmental exposure of rats to the pesticide chlorpyrifos (CPF) causes persistent neurobehavioral impairment. In a parallel series of studies with zebrafish, we have also found persisting behavioral dysfunction after developmental CPF exposure. We have developed a battery of measures of zebrafish behavior, which are reliable and sensitive to toxicant-induced damage. This study determined the critical duration of developmental CPF exposure for causing persisting neurobehavioral effects. Tests of sensorimotor response (tap startle response and habituation), stress response (novel tank diving test) and learning (3-chamber tank spatial discrimination) were conducted with adult zebrafish after early developmental CPF exposure. The CPF exposure level was 100 ng/ml with durations of 0-1, 0-2, 0-3, 0-4 and 0-5 days after fertilization. Developmental CPF exposure had persisting behavioral effects in zebrafish tested as adults. In the tactile startle test, CPF exposed fish showed decreased habituation to startle and a trend toward increased overall startle response. In the novel tank exploration test, exposed fish showed decreased escape diving response and increased swimming activity. In the 3-chamber learning test, the 0-5 day CPF exposure group had a significantly lower learning rate. There was evidence for persisting declines in brain dopamine and norepinepherine levels after developmental CPF exposure. In all of the measures the clearest persistent effects were seen in fish exposed for the full duration of five days after fertilization. In a follow-up experiment there were some indications for persisting behavioral effects after exposure during only the later phase of this developmental window. This study demonstrated the selective long-term neurobehavioral alterations caused by exposure to CPF in zebrafish. The zebrafish model can facilitate the determination of the molecular mechanisms underlying long-term neurobehavioral impairment after developmental toxicant exposure.
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Carr RL, Borazjani A, Ross MK. Effect of developmental chlorpyrifos exposure, on endocannabinoid metabolizing enzymes, in the brain of juvenile rats. Toxicol Sci 2011; 122:112-20. [PMID: 21507991 DOI: 10.1093/toxsci/kfr081] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The endogenous cannabinoids 2-arachidonoylglycerol (2-AG) and arachidonoyl ethanolamide (AEA or anandamide) play vital roles during nervous system development including regulating axonal guidance and synaptogenesis. The enzymatic degradation of 2-AG and AEA is highly susceptible to inhibition by organophosphate compounds in vitro. Furthermore, acute in vivo exposure of adult animals to the agricultural insecticide chlorpyrifos (CPS) caused moderate inhibition of both 2-AG and AEA hydrolysis. However, the effects of repeated exposure to lower levels of CPS, especially during development, on endocannabinoid metabolism in the brain is not known. To examine this, rat pups were orally exposed daily from postnatal days 10-16 to either 1.0, 2.5, or 5.0 mg/kg CPS. Body weight gain was reduced by 5.0 mg/kg on all days of treatment whereas 2.5 mg/kg reduced the weight gain only on the last two days of treatment. At 4-h postexposure on day 16, forebrain cholinesterase (ChE) activity and hydrolysis of 2-AG and AEA were inhibited in a dose-related manner, and the extent of inhibition from highest to lowest level was AEA hydrolysis > ChE activity > 2-AG hydrolysis. The extent of inhibition of AEA hydrolysis was approximately twice than that of ChE activity with AEA hydrolysis being virtually eliminated by 2.5 and 5.0 mg/kg and 1.0 mg/kg causing 40% inhibition. The sensitivity of AEA hydrolysis, compared with canonical targets such as ChE activity, suggests a potential alternative developmental target for CPS. Inhibition of AEA hydrolysis could result in accumulation of endocannabinoids, which could alter normal endocannabinoid transmission during brain maturation.
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Affiliation(s)
- Russell L Carr
- Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762-6100, USA.
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Chen WQ, Yuan L, Xue R, Li YF, Su RB, Zhang YZ, Li J. Repeated exposure to chlorpyrifos alters the performance of adolescent male rats in animal models of depression and anxiety. Neurotoxicology 2011; 32:355-61. [PMID: 21453723 DOI: 10.1016/j.neuro.2011.03.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 03/16/2011] [Accepted: 03/21/2011] [Indexed: 10/18/2022]
Abstract
Chlorpyrifos (CPF) is a broad spectrum, highly effective organophosphorus (OP) pesticide that has been largely used worldwide. Over the past decades, numerous studies have assessed the potential neurotoxic effects of either acute or chronic exposure to CPF on developing brain. Despite being an acetylcholinersterase inhibitor, the effects of CPF are not only confined to cholinergic system, but are involved in a wide variety of neurotransmitter systems, especially the serotonin (5-HT) system, which leads to long-lasting changes in 5-HT-related emotional behaviors. In our present study, 4-week-old adolescent male Sprague-Dawley rats were repeatedly exposed to CPF at daily doses of 10, 20, 40, 80, and 160 mg/kg/day (s.c., 7 days), and then subjected to a battery of emotional behavioral tests that related to serotonergic function in order to determine CPF effects in adolescent rats. Results in behavioral tests demonstrated CPF significantly increased the entries to and time spent in the open arms in the elevated plus-maze test at the dose of 40-160 mg/kg, the number of shocks in the Vogel's conflict test at the dose of 20-160 mg/kg, and significantly decreased the latency to feed in the novelty-suppressed feeding test in both dose range. Interestingly, in the forced swimming test, at the dose of 10mg/kg, CPF significantly increased the immobility time, whereas it significantly decreased the immobility time at the dose of 160 mg/kg. Our data suggest that repeated exposure to CPF elicits alterations of the emotional behaviors related to serotonergic nervous system in adolescent male rats. However, the underlying mechanism needs further investigations.
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Affiliation(s)
- Wen-Qiang Chen
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing, Haidian District, PR China
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Fan C, Tsui L, Liao MC. Parathion degradation and its intermediate formation by Fenton process in neutral environment. CHEMOSPHERE 2011; 82:229-236. [PMID: 21035166 DOI: 10.1016/j.chemosphere.2010.10.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 09/28/2010] [Accepted: 10/04/2010] [Indexed: 05/30/2023]
Abstract
The purpose of this study is to investigate parathion degradation by Fenton process in neutral environment. The initial parathion concentration for all the degradation experiments was 20 ppm. For hydrogen ion effect on Fenton degradation, the pH varied from 2 to 8 at the [H₂O₂] to [Fe²(+)] ratio of 2-2 mM, and the result showed pH 3 as the most effective environment for parathion degradation by Fenton process. Apparent degradation was also observed at pH 7. The subsequent analysis for parathion degradation was conducted at pH 7 because most environmental parathion exists in the neutral environment. Comparing the parathion degradation results at various Fenton dosages revealed that at Fe²(+) concentrations of 0.5, 1.0 and 1.5 mM, the Fenton reagent ratio ([H₂O₂]/[Fe²(+)]) for best-removing performance were found as 4, 3, and 2, resulting in the removal efficiencies of 19%, 48% and 36%, respectively. Further increase in Fe²(+) concentration did not cause any increase of the optimum Fenton reagent ratio for the best parathion removal. The result from LC-MS also indicated that hydroxyl radicals might attack the PS double bond, the single bonds connecting nitro-group, nitrophenol, or the single bond within ethyl groups of parathion molecules forming paraoxons, nitrophenols, nitrate/nitrite, thiophosphates, and other smaller molecules. Lastly, the parathion degradation by Fenton process at the presence of humic acids was investigated, and the results showed that the presence of 10 mg L⁻¹ of humic acids in the aqueous solution enhanced the parathion removal by Fenton process twice as much as that without the presence of humic acids.
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Affiliation(s)
- Chihhao Fan
- Department of Safety Health and Environmental Engineering, Ming Chi University of Technology, Taipei County, Taiwan.
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