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Lozovaya N, Moumen A, Hammond C. Basal Forebrain Cholinergic Neurons Have Specific Characteristics during the Perinatal Period. eNeuro 2024; 11:ENEURO.0538-23.2024. [PMID: 38755010 PMCID: PMC11137802 DOI: 10.1523/eneuro.0538-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 04/09/2024] [Accepted: 05/05/2024] [Indexed: 05/18/2024] Open
Abstract
Cholinergic neurons of the basal forebrain represent the main source of cholinergic innervation of large parts of the neocortex and are involved in adults in the modulation of attention, memory, and arousal. During the first postnatal days, they play a crucial role in the development of cortical neurons and cortical cytoarchitecture. However, their characteristics, during this period have not been studied. To understand how they can fulfill this role, we investigated the morphological and electrophysiological maturation of cholinergic neurons of the substantia innominata-nucleus basalis of Meynert (SI/NBM) complex in the perinatal period in mice. We show that cholinergic neurons, whether or not they express gamma-aminobutyric acid (GABA) as a cotransmitter, are already functional at Embryonic Day 18. Until the end of the first postnatal week, they constitute a single population of neurons with a well developed dendritic tree, a spontaneous activity including bursting periods, and a short-latency response to depolarizations (early-firing). They are excited by both their GABAergic and glutamatergic afferents. During the second postnatal week, a second, less excitable, neuronal population emerges, with a longer delay response to depolarizations (late-firing), together with the hyperpolarizing action of GABAA receptor-mediated currents. This classification into early-firing (40%) and late-firing (60%) neurons is again independent of the coexpression of GABAergic markers. These results strongly suggest that during the first postnatal week, the specific properties of developing SI/NBM cholinergic neurons allow them to spontaneously release acetylcholine (ACh), or ACh and GABA, into the developing cortex.
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Berroug L, Laaroussi M, Essaidi O, Malqui H, Anarghou H, Chaoui AA, Najimi M, Chigr F. Sex-specific neurobehavioral and biochemical effects of developmental exposure to Malathion in offspring mice. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2215-2231. [PMID: 37804342 DOI: 10.1007/s00210-023-02749-2] [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: 07/03/2023] [Accepted: 09/25/2023] [Indexed: 10/09/2023]
Abstract
Malathion is an organophosphate pesticide (OP) commonly used in agriculture, industry, and veterinary medicine. Sex is a crucial factor in responding to neurotoxicants, yet the sex-specific effects of OP exposure, particularly neurological impairments following chronic low-level exposure remains limited. Our study aims to evaluate the neurobehavioral and biochemical effects of developmental exposure to Malathion across sexes. Pregnant mice were exposed to a low oral dose of Malathion from gestation up to the weaning of the pups, which were individually gavaged with a similar dose regimen until postnatal day 70. Our results show that Malathion decreased body weight and food intake, reduced locomotor activity and recognition memory. Motor coordination and special memory were only altered in females, whereas we found a male-specific effect of Malathion on social behavior and marble burying. These alterations were accompanied by increased malondialdehyde (MDA), decreased brain acetylcholinesterase activity (AChE), and disrupted brain redox homeostasis. Our findings about the effects of Malathion exposure across sexes may, in part, contribute to understanding the dimorphic susceptibilities observed in neurological disorders.
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Affiliation(s)
- Laila Berroug
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Meriem Laaroussi
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Oumaima Essaidi
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Hafsa Malqui
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Hammou Anarghou
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Ahmed Ait Chaoui
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Mohamed Najimi
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
| | - Fatiha Chigr
- Biological Engineering Laboratory, Faculty of Science and Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco.
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3
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Keeley RJ, Prillaman ME, Scarlata M, Vrana A, Tsai PJ, Gomez JL, Bonaventura J, Lu H, Michaelides M, Stein EA. Adolescent nicotine administration increases nicotinic acetylcholine receptor binding and functional connectivity in specific cortico-striatal-thalamic circuits. Brain Commun 2022; 4:fcac291. [PMID: 36440101 PMCID: PMC9683397 DOI: 10.1093/braincomms/fcac291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 07/05/2022] [Accepted: 11/17/2022] [Indexed: 11/28/2023] Open
Abstract
Nicotine exposure is associated with regional changes in brain nicotinic acetylcholine receptors subtype expression patterns as a function of dose and age at the time of exposure. Moreover, nicotine dependence is associated with changes in brain circuit functional connectivity, but the relationship between such connectivity and concomitant regional distribution changes in nicotinic acetylcholine receptor subtypes following nicotine exposure is not understood. Although smoking typically begins in adolescence, developmental changes in brain circuits and nicotinic acetylcholine receptors following chronic nicotine exposure remain minimally investigated. Here, we combined in vitro nicotinic acetylcholine receptor autoradiography with resting state functional magnetic resonance imaging to measure changes in [3H]nicotine binding and α4ß2 subtype nicotinic acetylcholine receptor binding and circuit connectivity across the brain in adolescent (postnatal Day 33) and adult (postnatal Day 68) rats exposed to 6 weeks of nicotine administration (0, 1.2 and 4.8 mg/kg/day). Chronic nicotine exposure increased nicotinic acetylcholine receptor levels and induced discrete, developmental stage changes in regional nicotinic acetylcholine receptor subtype distribution. These effects were most pronounced in striatal, thalamic and cortical regions when nicotine was administered during adolescence but not in adults. Using these regional receptor changes as seeds, resting state functional magnetic resonance imaging identified dysregulations in cortico-striatal-thalamic-cortical circuits that were also dysregulated following adolescent nicotine exposure. Thus, nicotine-induced increases in cortical, striatal and thalamic nicotinic acetylcholine receptors during adolescence modifies processing and brain circuits within cortico-striatal-thalamic-cortical loops, which are known to be crucial for multisensory integration, action selection and motor output, and may alter the developmental trajectory of the adolescent brain. This unique multimodal study significantly advances our understanding of nicotine dependence and its effects on the adolescent brain.
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Affiliation(s)
- Robin J Keeley
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - McKenzie E Prillaman
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Miranda Scarlata
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Antonia Vrana
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Pei-Jung Tsai
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Juan L Gomez
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Jordi Bonaventura
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
- Departament de Patologia Terapèutica Experimental, Institut de Neurociènes, Universitat de Barcelona, Gran Via de les Corts Catalanes, 585, 08007 Barcelona, Spain
| | - Hanbing Lu
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Michael Michaelides
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
| | - Elliot A Stein
- National Institute on Drug Abuse, Intramural Research Program (NIDA-IRP), National Institutes of Health, Baltimore, MD 21224, USA
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Pandey P, Kaur G, Babu K. Crosstalk between neurons and glia through G-protein coupled receptors: Insights from Caenorhabditis elegans. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 193:119-144. [PMID: 36357074 DOI: 10.1016/bs.pmbts.2022.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The past decades have witnessed a dogmatic shift from glia as supporting cells in the nervous system to their active roles in neurocentric functions. Neurons and glia communicate and show bidirectional responses through tripartite synapses. Studies across species indicate that neurotransmitters released by neurons are perceived by glial receptors, which allow for gliotransmitter release. These gliotransmitters can result in activation of neurons via neuronal GPCR receptors. However, studies of these molecular interactions are in their infancy. Caenorhabditis elegans has a conserved neuron-glia architectural repertoire with molecular and functional resemblance to mammals. Further, glia in C. elegans can be manipulated through ablation and mutations allowing for deciphering of glial dependent processes in vivo at single glial resolutions. Here, we will review recent findings from vertebrate and invertebrate organisms with a focus on how C. elegans can be used to advance our understanding of neuron-glia interactions through GPCRs.
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Affiliation(s)
- Pratima Pandey
- Indian Institute of Science Education and Research, Mohali, Punjab, India.
| | - Gazaldeep Kaur
- National Agri-Food Biotechnology Institute, Mohali, Punjab, India
| | - Kavita Babu
- Indian Institute of Science, Bangalore, Karnataka, India.
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5
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Steinecke A, Bolton MM, Taniguchi H. Neuromodulatory control of inhibitory network arborization in the developing postnatal neocortex. SCIENCE ADVANCES 2022; 8:eabe7192. [PMID: 35263136 PMCID: PMC8906727 DOI: 10.1126/sciadv.abe7192] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 01/19/2022] [Indexed: 06/14/2023]
Abstract
Interregional neuronal communication is pivotal to instructing and adjusting cortical circuit assembly. Subcortical neuromodulatory systems project long-range axons to the cortex and affect cortical processing. However, their roles and signaling mechanisms in cortical wiring remain poorly understood. Here, we explored whether and how the cholinergic system regulates inhibitory axonal ramification of neocortical chandelier cells (ChCs), which control spike generation by innervating axon initial segments of pyramidal neurons. We found that acetylcholine (ACh) signaling through nicotinic ACh receptors (nAChRs) and downstream T-type voltage-dependent calcium (Ca2+) channels cell-autonomously controls axonal arborization in developing ChCs through regulating filopodia initiation. This signaling axis shapes the basal Ca2+ level range in varicosities where filopodia originate. Furthermore, the normal development of ChC axonal arbors requires proper levels of activity in subcortical cholinergic neurons. Thus, the cholinergic system regulates inhibitory network arborization in the developing neocortex and may tune cortical circuit properties depending on early-life experiences.
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Affiliation(s)
- André Steinecke
- Development and Function of Inhibitory Neural Circuits, Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - McLean M. Bolton
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Hiroki Taniguchi
- Development and Function of Inhibitory Neural Circuits, Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
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Ramírez V, Gálvez-Ontiveros Y, González-Domenech PJ, Baca MÁ, Rodrigo L, Rivas A. Role of endocrine disrupting chemicals in children's neurodevelopment. ENVIRONMENTAL RESEARCH 2022; 203:111890. [PMID: 34418446 DOI: 10.1016/j.envres.2021.111890] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/08/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
Environmental stressors, like endocrine disrupting chemicals (EDC), are considered important contributors to the increased rates of neurodevelopmental dysfunctions. Considering the cumulative research on adverse neurodevelopmental effects associated with prenatal exposure to EDC, the purpose of this study was to review the available limited literature about the effects of postnatal exposure to EDC on child neurodevelopment and behaviour. Despite widespread children's exposure to EDC, there are a limited number of epidemiological studies on the association of this exposure with neurodevelopmental disorders, in particular in the postnatal period. The available research suggests that postnatal EDC exposure is related to adverse neurobehavioral outcomes in children; however the underlying mechanisms of action remain unclear. Timing of exposure is a key factor determining potential neurodevelopmental consequences, hence studying the impact of multiple EDC co-exposure in different vulnerable life periods could guide the identification of sensitive subpopulations. Most of the reviewed studies did not take into account sex differences in the EDC effects on children neurodevelopment. We believe that the inclusion of sex in the study design should be considered as the role of EDC on children neurodevelopment are likely sex-specific and should be taken into consideration when determining susceptibility and potential mechanisms of action.
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Affiliation(s)
- Viviana Ramírez
- Department of Nutrition and Food Science, University of Granada, Granada, Spain
| | - Yolanda Gálvez-Ontiveros
- Department of Nutrition and Food Science, University of Granada, Granada, Spain; Instituto de Investigación Biosanitaria ibs. GRANADA, Granada, Spain
| | - Pablo José González-Domenech
- Instituto de Investigación Biosanitaria ibs. GRANADA, Granada, Spain; Department of Psychiatry, University of Granada, Granada, Spain
| | | | - Lourdes Rodrigo
- Department of Legal Medicine and Toxicology, University of Granada, Granada, Spain.
| | - Ana Rivas
- Department of Nutrition and Food Science, University of Granada, Granada, Spain; Instituto de Investigación Biosanitaria ibs. GRANADA, Granada, Spain
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Nayeri T, Sarvi S, Daryani A. Toxoplasmosis: Targeting neurotransmitter systems in psychiatric disorders. Metab Brain Dis 2022; 37:123-146. [PMID: 34476718 DOI: 10.1007/s11011-021-00824-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 08/14/2021] [Indexed: 12/30/2022]
Abstract
The most common form of the disease caused by Toxoplasma gondii (T. gondii) is latent toxoplasmosis due to the formation of tissue cysts in various organs, such as the brain. Latent toxoplasmosis is probably a risk factor in the development of some neuropsychiatric disorders. Behavioral changes after infection are caused by the host immune response, manipulation by the parasite, central nervous system (CNS) inflammation, as well as changes in hormonal and neuromodulator relationships. The present review focused on the exact mechanisms of T. gondii effect on the alteration of behavior and neurotransmitter levels, their catabolites and metabolites, as well as the interaction between immune responses and this parasite in the etiopathogenesis of psychiatric disorders. The dysfunction of neurotransmitters in the neural transmission is associated with several neuropsychiatric disorders. However, further intensive studies are required to determine the effect of this parasite on altering the level of neurotransmitters and the role of neurotransmitters in the etiology of host behavioral changes.
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Affiliation(s)
- Tooran Nayeri
- Toxoplasmosis Research Center, Mazandaran University of Medical Sciences, Sari, Iran
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
- Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran
| | - Shahabeddin Sarvi
- Toxoplasmosis Research Center, Mazandaran University of Medical Sciences, Sari, Iran
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ahmad Daryani
- Toxoplasmosis Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
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Brooks AC, Henderson BJ. Systematic Review of Nicotine Exposure's Effects on Neural Stem and Progenitor Cells. Brain Sci 2021; 11:172. [PMID: 33573081 PMCID: PMC7912116 DOI: 10.3390/brainsci11020172] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 12/24/2022] Open
Abstract
While various modalities of chronic nicotine use have been associated with numerous negative consequences to human health, one possible benefit of nicotine exposure has been uncovered. The discovery of an inverse correlation between smoking and Parkinson's disease, and later Alzheimer's disease as well, motivated investigation of nicotine as a neuroprotective agent. Some studies have demonstrated that nicotine elicits improvements in cognitive function. The hippocampus, along with the subventricular zone (SVZ), is a distinct brain region that allow for ongoing postnatal neurogenesis throughout adulthood and plays a major role in certain cognitive behaviors like learning and memory. Therefore, one hypothesis underlying nicotine-induced neuroprotection is possible effects on neural stem cells and neural precursor cells. On the other hand, nicotine withdrawal frequently leads to cognitive impairments, particularly in hippocampal-dependent behaviors, possibly suggesting an impairment of hippocampal neurogenesis with nicotine exposure. This review discusses the current body of evidence on nicotine's effects on neural stem cells and neural progenitors. Changes in neural stem cell proliferation, survival, intracellular dynamics, and differentiation following acute and chronic nicotine exposure are examined.
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Affiliation(s)
- Arrin C. Brooks
- Department of Biomedical Science, Joan C Edwards School of Medicine, Marshall University, Huntington, WV 25545, USA;
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Fuentes-Cano MA, Bustamante-Valdez DJ, Durán P. Perinatal exposure to nicotine disrupts circadian locomotor and learning efficiency rhythms in juvenile mice. Brain Struct Funct 2020; 225:2287-2297. [PMID: 32789697 DOI: 10.1007/s00429-020-02126-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 07/31/2020] [Indexed: 12/19/2022]
Abstract
The increased rates of nicotine exposure by electronic nicotine delivery systems (vaping), ingestion, or patches during pregnancy as an alternative to the smoking of tobacco arise concerns about the neurodevelopmental, cognitive, and behavioral long-term consequences in the juvenile offspring. Nowadays, the use of electronic cigarettes as supposed a safer smoking alternative has been increased mainly in young females at reproductive age, due to the "safety" misconception. However, previous studies suggest that exposure to nicotine during pregnancy and prenatal development may lead to detrimental effects in the postnatal lifespan. Nicotine, as an alkaloid, alters the reward system acting as acetylcholine (ACh) agonist on nicotinic cholinergic receptors (nAChRs). In early brain development, the cholinergic system is also involved in neurite outgrowth, cell survival, proliferation, differentiation, neurogenesis, and many other critical processes being considered as a developmental signal marker. The nicotine noxious effect at those early stages may impact the system programming and plasticity in the long-term postnatal life. In this study, we analyze the circadian locomotor activity and learning efficiency rhythms in the juvenile male offspring of mice exposed to nicotine through pregnancy and lactation. Attenuated rhythm amplitude and relative power of the circadian component were found in the nicotine exposed offspring (pN). The acrophase (the best performance during a 24-h cycle) of learning efficiency was delayed and the long-term memory consolidation task failed after 8 days of learning experience. The aforementioned results suggest nicotine exposure in uterus modifies the circadian modulation related to the memory consolidation and locomotor systems as well as its environmental temporal synchronization.
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Affiliation(s)
- Martin A Fuentes-Cano
- Laboratorio de Biología Animal Experimental, Depto. Biología Celular, Facultad de Ciencias, Neurofisiología del Desarrollo y Ritmos Biológicos, Universidad Nacional Autónoma de México, Av. Universidad 3000, Copilco-Universidad, Coyoacán, México City, 04510, México
| | - Dulce J Bustamante-Valdez
- Laboratorio de Biología Animal Experimental, Depto. Biología Celular, Facultad de Ciencias, Neurofisiología del Desarrollo y Ritmos Biológicos, Universidad Nacional Autónoma de México, Av. Universidad 3000, Copilco-Universidad, Coyoacán, México City, 04510, México
| | - Pilar Durán
- Laboratorio de Biología Animal Experimental, Depto. Biología Celular, Facultad de Ciencias, Neurofisiología del Desarrollo y Ritmos Biológicos, Universidad Nacional Autónoma de México, Av. Universidad 3000, Copilco-Universidad, Coyoacán, México City, 04510, México.
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Salama M, Lotfy A, Fathy K, Makar M, El-emam M, El-gamal A, El-gamal M, Badawy A, Mohamed WM, Sobh M. Developmental neurotoxic effects of Malathion on 3D neurosphere system. Appl Transl Genom 2015; 7:13-8. [PMID: 27054080 PMCID: PMC4803784 DOI: 10.1016/j.atg.2015.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 07/04/2015] [Accepted: 07/07/2015] [Indexed: 02/04/2023]
Abstract
Developmental neurotoxicity (DNT) refers to the toxic effects induced by various chemicals on brain during the early childhood period. As human brains are vulnerable during this period, various chemicals would have significant effects on brains during early childhood. Some toxicants have been confirmed to induce developmental toxic effects on CNS; however, most of agents cannot be identified with certainty. This is because available animal models do not cover the whole spectrum of CNS developmental periods. A novel alternative method that can overcome most of the limitations of the conventional techniques is the use of 3D neurosphere system. This in-vitro system can recapitulate many of the changes during the period of brain development making it an ideal model for predicting developmental neurotoxic effects. In the present study we verified the possible DNT of Malathion, which is one of organophosphate pesticides with suggested possible neurotoxic effects on nursing children. Three doses of Malathion (0.25 μM, 1 μM and 10 μM) were used in cultured neurospheres for a period of 14 days. Malathion was found to affect proliferation, differentiation and viability of neurospheres, these effects were positively correlated to doses and time progress. This study confirms the DNT effects of Malathion on 3D neurosphere model. Further epidemiological studies will be needed to link these results to human exposure and effects data.
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Affiliation(s)
- Mohamed Salama
- Medical Experimental Research Center, Mansura Medical School, Mansura University, Egypt
- Toxicology Dept., Mansura Medical School, Mansura University, Egypt
| | - Ahmed Lotfy
- Medical Experimental Research Center, Mansura Medical School, Mansura University, Egypt
| | - Khaled Fathy
- Medical Experimental Research Center, Mansura Medical School, Mansura University, Egypt
| | - Maria Makar
- Mansoura Manchester Medical Program, Mansura Medical School, Mansura University, Egypt
| | - Mona El-emam
- Mansoura Manchester Medical Program, Mansura Medical School, Mansura University, Egypt
| | - Aya El-gamal
- Toxicology Dept., Mansura Medical School, Mansura University, Egypt
| | - Mohamed El-gamal
- Toxicology Dept., Mansura Medical School, Mansura University, Egypt
| | - Ahmad Badawy
- Obstetrics and Gynaecology Dept., Mansura Medical School, Mansura University, Egypt
| | - Wael M.Y. Mohamed
- Clinical Pharmacology Dept., Menoufia Medical School, Menoufia University, Egypt
- Corresponding author.
| | - Mohamed Sobh
- Medical Experimental Research Center, Mansura Medical School, Mansura University, Egypt
- UNC, Mansoura University, Egypt
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Slotkin TA, Skavicus S, Card J, Levin ED, Seidler FJ. Amelioration strategies fail to prevent tobacco smoke effects on neurodifferentiation: Nicotinic receptor blockade, antioxidants, methyl donors. Toxicology 2015; 333:63-75. [PMID: 25891525 DOI: 10.1016/j.tox.2015.04.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/12/2015] [Accepted: 04/14/2015] [Indexed: 12/12/2022]
Abstract
Tobacco smoke exposure is associated with neurodevelopmental disorders. We used neuronotypic PC12 cells to evaluate the mechanisms by which tobacco smoke extract (TSE) affects neurodifferentiation. In undifferentiated cells, TSE impaired DNA synthesis and cell numbers to a much greater extent than nicotine alone; TSE also impaired cell viability to a small extent. In differentiating cells, TSE enhanced cell growth at the expense of cell numbers and promoted emergence of the dopaminergic phenotype. Nicotinic receptor blockade with mecamylamine was ineffective in preventing the adverse effects of TSE and actually enhanced the effect of TSE on the dopamine phenotype. A mixture of antioxidants (vitamin C, vitamin E, N-acetyl-l-cysteine) provided partial protection against cell loss but also promoted loss of the cholinergic phenotype in response to TSE. Notably, the antioxidants themselves altered neurodifferentiation, reducing cell numbers and promoting the cholinergic phenotype at the expense of the dopaminergic phenotype, an effect that was most prominent for N-acetyl-l-cysteine. Treatment with methyl donors (vitamin B12, folic acid, choline) had no protectant effect and actually enhanced the cell loss evoked by TSE; they did have a minor, synergistic interaction with antioxidants protecting against TSE effects on growth. Thus, components of tobacco smoke perturb neurodifferentiation through mechanisms that cannot be attributed to the individual effects of nicotine, oxidative stress or interference with one-carbon metabolism. Consequently, attempted amelioration strategies may be partially effective at best, or, as seen here, can actually aggravate injury by interfering with normal developmental signals and/or by sensitizing cells to TSE effects on neurodifferentiation.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Samantha Skavicus
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Jennifer Card
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA
| | - Frederic J Seidler
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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12
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Impact of prenatal nicotine on the structure of midbrain dopamine regions in the rat. Brain Struct Funct 2015; 221:1939-53. [PMID: 25716298 DOI: 10.1007/s00429-015-1014-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 02/15/2015] [Indexed: 10/23/2022]
Abstract
In utero exposure of rats to nicotine (NIC) provides a useful animal model for studying the impact of smoking during pregnancy on human offspring. Certain sequelae of prenatal NIC exposure suggest an impact on the development of the midbrain dopamine (DA) system, which receives a robust cholinergic innervation from the mesopontine tegmentum. We therefore investigated whether prenatal NIC induced structural changes in cells and synapses within the midbrain that persisted into adulthood. Osmotic minipumps delivering either sodium bitartrate (vehicle; VEH) or NIC bitartrate at 2 mg/kg/day were implanted into nine timed-pregnant dams at E4. At birth, rat pups were culled to litters of six males each, and the litters were cross-fostered. Plasma levels of NIC and cotinine from killed pups provided evidence of NIC exposure in utero. Pups separated from dams at weaning showed a trend toward reduced locomotor activity at this time point but not when tested again in adulthood. Adult rats were killed for anatomical studies. Estimates of brain size and volume did not vary with NIC treatment. Midbrain sections stained for Nissl or by immunoperoxidase for tyrosine hydroxylase and analyzed using unbiased stereology revealed no changes in volume or cell number in the substantia nigra compacta or ventral tegmental area as a result of NIC exposure. Within the ventral tegmental area, electron microscopic physical disector analysis showed no significant differences in the number of axon terminals or the number of asymmetric (putative excitatory) or symmetric (putative inhibitory) synapses. Although too infrequent to estimate by unbiased stereology, no obvious difference in the proportion of cholinergic axons was noted in NIC- versus VEH-treated animals. These data suggest that activation of nicotinic receptors during prenatal development induces no significant modifications in the structure of cells in the ventral midbrain when assessed in adulthood.
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Ross EJ, Graham DL, Money KM, Stanwood GD. Developmental consequences of fetal exposure to drugs: what we know and what we still must learn. Neuropsychopharmacology 2015; 40:61-87. [PMID: 24938210 PMCID: PMC4262892 DOI: 10.1038/npp.2014.147] [Citation(s) in RCA: 253] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 05/29/2014] [Accepted: 06/02/2014] [Indexed: 01/13/2023]
Abstract
Most drugs of abuse easily cross the placenta and can affect fetal brain development. In utero exposures to drugs thus can have long-lasting implications for brain structure and function. These effects on the developing nervous system, before homeostatic regulatory mechanisms are properly calibrated, often differ from their effects on mature systems. In this review, we describe current knowledge on how alcohol, nicotine, cocaine, amphetamine, Ecstasy, and opiates (among other drugs) produce alterations in neurodevelopmental trajectory. We focus both on animal models and available clinical and imaging data from cross-sectional and longitudinal human studies. Early studies of fetal exposures focused on classic teratological methods that are insufficient for revealing more subtle effects that are nevertheless very behaviorally relevant. Modern mechanistic approaches have informed us greatly as to how to potentially ameliorate the induced deficits in brain formation and function, but conclude that better delineation of sensitive periods, dose-response relationships, and long-term longitudinal studies assessing future risk of offspring to exhibit learning disabilities, mental health disorders, and limited neural adaptations are crucial to limit the societal impact of these exposures.
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Affiliation(s)
- Emily J Ross
- Chemical & Physical Biology Program, Vanderbilt University, Nashville, TN, USA
| | - Devon L Graham
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Kelli M Money
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, USA
| | - Gregg D Stanwood
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- The Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN, USA
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Suarez-Lopez JR, Himes JH, Jacobs DR, Alexander BH, Gunnar MR. Acetylcholinesterase activity and neurodevelopment in boys and girls. Pediatrics 2013; 132:e1649-58. [PMID: 24249815 PMCID: PMC3838526 DOI: 10.1542/peds.2013-0108] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Organophosphate exposures can affect children's neurodevelopment, possibly due to neurotoxicity induced by acetylcholinesterase (AChE) inhibition, and may affect boys more than girls. We tested the hypothesis that lower AChE activity is associated with lower neurobehavioral development among children living in Ecuadorian floricultural communities. METHODS In 2008, we examined 307 children (age: 4-9 years; 52% male) and quantified AChE activity and neurodevelopment in 5 domains: attention/executive functioning, language, memory/learning, visuospatial processing, and sensorimotor (NEPSY-II test). Associations were adjusted for demographic and socioeconomic characteristics and height-for-age, flower worker cohabitation, and hemoglobin concentration. RESULTS Mean ± standard deviation AChE activity was 3.14 ± 0.49 U/mL (similar for both genders). The range of scores among neurodevelopment subtests was 5.9 to 10.7 U (standard deviation: 2.6-4.9 U). Girls had a greater mean attention/executive functioning domain score than boys. In boys only, there were increased odds ratios of low (<9th percentile) neurodevelopment among those in the lowest tertile versus the highest tertile of AChE activity (odds ratios: total neurodevelopment: 5.14 [95% confidence interval (CI): 0.84 to 31.48]; attention/executive functioning domain: 4.55 [95% CI: 1.19 to 17.38], memory/learning domain: 6.03 [95% CI: 1.17 to 31.05]) after adjustment for socioeconomic and demographic factors, height-for-age, and hemoglobin. Within these domains, attention, inhibition and long-term memory subtests were most affected. CONCLUSIONS Low AChE activity was associated with deficits in neurodevelopment, particularly in attention, inhibition, and memory in boys but not in girls. These critical cognitive skills affect learning and academic performance. Added precautions regarding secondary occupational pesticide exposure would be prudent.
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Affiliation(s)
- Jose R. Suarez-Lopez
- Department of Family and Preventive Medicine, University of California–San Diego, La Jolla, California;,Fundación Cimas del Ecuador; Divisions of
| | | | - David R. Jacobs
- Epidemiology and Community Health and,Department of Nutrition, School of Medicine, University of Oslo
| | | | - Megan R. Gunnar
- Institute of Child Development, University of Minnesota; and
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Fu W, Ruangkittisakul A, MacTavish D, Baker G, Ballanyi K, Jhamandas J. Activity and metabolism-related Ca2+ and mitochondrial dynamics in co-cultured human fetal cortical neurons and astrocytes. Neuroscience 2013; 250:520-35. [DOI: 10.1016/j.neuroscience.2013.07.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/06/2013] [Accepted: 07/08/2013] [Indexed: 01/19/2023]
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Porciúncula LO, Sallaberry C, Mioranzza S, Botton PHS, Rosemberg DB. The Janus face of caffeine. Neurochem Int 2013; 63:594-609. [PMID: 24055856 DOI: 10.1016/j.neuint.2013.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 09/04/2013] [Accepted: 09/06/2013] [Indexed: 12/20/2022]
Abstract
Caffeine is certainly the psychostimulant substance most consumed worldwide. Over the past years, chronic consumption of caffeine has been associated with prevention of cognitive decline associated to aging and mnemonic deficits of brain disorders. While its preventive effects have been reported extensively, the cognitive enhancer properties of caffeine are relatively under debate. Surprisingly, there are scarce detailed ontogenetic studies focusing on neurochemical parameters related to the effects of caffeine during prenatal and earlier postnatal periods. Furthermore, despite the large number of epidemiological studies, it remains unclear how safe is caffeine consumption during pregnancy and brain development. Thus, the purpose of this article is to review what is currently known about the actions of caffeine intake on neurobehavioral and adenosinergic system during brain development. We also reviewed other neurochemical systems affected by caffeine, but not only during brain development. Besides, some recent epidemiological studies were also outlined with the control of "pregnancy signal" as confounding variable. The idea is to tease out how studies on the impact of caffeine consumption during brain development deserve more attention and further investigation.
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Affiliation(s)
- Lisiane O Porciúncula
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil.
| | - Cássia Sallaberry
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil
| | - Sabrina Mioranzza
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil
| | - Paulo Henrique S Botton
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil
| | - Denis B Rosemberg
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil; Laboratório de Genética e Ecotoxicologia Molecular, Programa de Pós-graduação em Ciências Ambientais, Área de Ciências Exatas e Ambientais, Universidade Comunitária da Região de Chapecó. Avenida Senador Attílio Fontana, 591E, 89809-000 Chapecó/SC, Brazil
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17
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Slotkin TA, Card J, Infante A, Seidler FJ. Prenatal dexamethasone augments the sex-selective developmental neurotoxicity of chlorpyrifos: implications for vulnerability after pharmacotherapy for preterm labor. Neurotoxicol Teratol 2013; 37:1-12. [PMID: 23416428 DOI: 10.1016/j.ntt.2013.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 01/28/2013] [Accepted: 02/02/2013] [Indexed: 01/01/2023]
Abstract
Glucocorticoids are routinely given in preterm labor and are also elevated by maternal stress; organophosphate exposures are virtually ubiquitous, so coexposures to these two agents are pervasive. We administered dexamethasone to pregnant rats on gestational days 17-19 at a standard therapeutic dose (0.2mg/kg); offspring were then given chlorpyrifos on postnatal days 1-4, at a dose (1mg/kg) that produces barely-detectable (<10%) inhibition of brain cholinesterase activity. We evaluated indices for acetylcholine (ACh) synaptic function throughout adolescence, young adulthood and later adulthood, in brain regions possessing the majority of ACh projections and cell bodies; we measured nicotinic ACh receptor binding, hemicholinium-3 binding to the presynaptic choline transporter and choline acetyltransferase activity, all known targets for the adverse developmental effects of dexamethasone and chlorpyrifos given individually. Dexamethasone did not enhance the systemic toxicity of chlorpyrifos, as evidenced by weight gain and measurements of cholinesterase inhibition during chlorpyrifos treatment. Nevertheless, it enhanced the loss of presynaptic ACh function selectively in females, who ordinarily show sparing of organophosphate developmental neurotoxicity relative to males. Females receiving the combined treatment showed decrements in choline transporter binding and choline acetyltransferase activity that were unique (not found with either treatment alone), as well as additive decrements in nicotinic receptor binding. On the other hand, males given dexamethasone showed no augmentation of the effects of chlorpyrifos. Our findings indicate that prior dexamethasone exposure could create a subpopulation that is especially vulnerable to the adverse effects of organophosphates or other developmental neurotoxicants.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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N’Go PK, Azzaoui FZ, Soro PR, Samih M, Ahami AOT, Najimi M, Chigr F. Developmental Effects of Malathion Exposure on Recognition Memory and Spatial Learning in Males Wistar Rats. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jbbs.2013.33033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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N’Go PK, Azzaoui FZ, Ahami AOT, Soro PR, Najimi M, Chigr F. Developmental effects of Malathion exposure on locomotor activity and anxiety-like behavior in Wistar rat. Health (London) 2013. [DOI: 10.4236/health.2013.53a080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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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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21
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Uggini GK, Patel PV, Balakrishnan S. Embryotoxic and teratogenic effects of pesticides in chick embryos: a comparative study using two commercial formulations. ENVIRONMENTAL TOXICOLOGY 2012; 27:166-74. [PMID: 20607816 DOI: 10.1002/tox.20627] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/22/2010] [Accepted: 04/24/2010] [Indexed: 05/15/2023]
Abstract
Developmental toxicity of two different classes of commercial formulations of insecticides was studied by in ovo treatment of fertilized Rhode Island Red eggs. The first one was a combination of chlorpyrifos and cypermethrin and the second one was spinosad, a fermentation product of soil bacterium, Actinomycetes. In this study, the combination pesticide and spinosad of different concentrations were administered as a single dose in ovo in volumes of 50 μL per each egg on day "0" of incubation. Embryonic growth and development, morphological and skeletal malformations, and hatchability were assessed. The combination insecticide induced explicit alterations in the embryonic growth and development and resulted in malformations particularly to the axial and appendicular skeletal structures, whereas the changes were trivial in case of the spinosad exposure.
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Affiliation(s)
- Gowri K Uggini
- Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390 002, India
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22
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Abstract
The cholinergic drive enhances input processing in attentional and mnemonic context by interacting with the activity of prefrontal-hippocampal networks. During development, acetylcholine modulates neuronal proliferation, differentiation, and synaptic plasticity, yet its contribution to the maturation of cognitive processing resulting from early entrainment of neuronal networks in oscillatory rhythms remains widely unknown. Here we show that cholinergic projections growing into the rat prefrontal cortex (PFC) toward the end of the first postnatal week boost the generation of nested gamma oscillations superimposed on discontinuous spindle bursts by acting on functional muscarinic but not nicotinic receptors. Although electrical stimulation of cholinergic nuclei increased the occurrence of nested gamma spindle bursts by 41%, diminishment of the cholinergic input by either blockade of the receptors or chronic immunotoxic lesion had the opposite effect. This activation of locally generated gamma episodes by direct cholinergic projections to the PFC was accompanied by indirect modulation of underlying spindle bursts via cholinergic control of hippocampal theta activity. With ongoing maturation and switch of network activity from discontinuous bursts to continuous theta-gamma rhythms, accumulating cholinergic projections acting on both muscarinic and nicotinic receptors mediated the transition from high-amplitude slow to low-amplitude fast rhythms in the PFC. By exerting multiple actions on the oscillatory entrainment of developing prefrontal-hippocampal networks, the cholinergic input may refine them for later gating processing in executive and mnemonic tasks.
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23
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Network, cellular, and molecular mechanisms underlying long-term memory formation. Curr Top Behav Neurosci 2012; 15:73-115. [PMID: 22976275 DOI: 10.1007/7854_2012_229] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The neural network stores information through activity-dependent synaptic plasticity that occurs in populations of neurons. Persistent forms of synaptic plasticity may account for long-term memory storage, and the most salient forms are the changes in the structure of synapses. The theory proposes that encoding should use a sparse code and evidence suggests that this can be achieved through offline reactivation or by sparse initial recruitment of the network units. This idea implies that in some cases the neurons that underwent structural synaptic plasticity might be a subpopulation of those originally recruited; However, it is not yet clear whether all the neurons recruited during acquisition are the ones that underwent persistent forms of synaptic plasticity and responsible for memory retrieval. To determine which neural units underlie long-term memory storage, we need to characterize which are the persistent forms of synaptic plasticity occurring in these neural ensembles and the best hints so far are the molecular signals underlying structural modifications of the synapses. Structural synaptic plasticity can be achieved by the activity of various signal transduction pathways, including the NMDA-CaMKII and ACh-MAPK. These pathways converge with the Rho family of GTPases and the consequent ERK 1/2 activation, which regulates multiple cellular functions such as protein translation, protein trafficking, and gene transcription. The most detailed explanation may come from models that allow us to determine the contribution of each piece of this fascinating puzzle that is the neuron and the neural network.
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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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25
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Nocturnal Frontal Lobe Epilepsy: New pathophysiological interpretations. Sleep Med 2011; 12 Suppl 2:S39-42. [DOI: 10.1016/j.sleep.2011.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 10/11/2011] [Accepted: 10/12/2011] [Indexed: 11/22/2022]
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Acker CI, Souza ACG, Pinton S, da Rocha JT, Friggi CA, Zanella R, Nogueira CW. Repeated malathion exposure induces behavioral impairment and AChE activity inhibition in brains of rat pups. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2011; 74:2310-2315. [PMID: 21855146 DOI: 10.1016/j.ecoenv.2011.07.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 07/26/2011] [Accepted: 07/30/2011] [Indexed: 05/31/2023]
Abstract
The present study evaluated if repeated malathion administration would cause behavioral impairment in rat pups. Na+K+ ATPase and acetylcholinesterase (AChE) activities were investigated in brains of rat pups. Malathion was administered (100 or 200 mg/kg) orally (p.o.), once a day for four consecutive days. Rat pups were submitted to behavioral tests on the 5th day, 24 h after the last malathion administration. Malathion at the dose of 200 mg/kg caused a significant increase in the negative geotaxis latency and a decrease in the rotarod latency of rat pups. Rat pups exposed to malathion at both doses showed a significant decrease in the forelimb support latency and an inhibition of brain AChE activity. Repeated exposure of rat pups to malathion caused a decrease in motor coordination, vestibular function and muscular strength/coordination. The brain activity of AChE is involved in the behavioral alterations caused by malathion in rat pups.
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Affiliation(s)
- Carmine Inês Acker
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, CEP 97105-900, RS, Brazil
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27
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Slotkin TA, Seidler FJ. Mimicking maternal smoking and pharmacotherapy of preterm labor: fetal nicotine exposure enhances the effect of late gestational dexamethasone treatment on noradrenergic circuits. Brain Res Bull 2011; 86:435-40. [PMID: 21875656 DOI: 10.1016/j.brainresbull.2011.08.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 08/11/2011] [Accepted: 08/13/2011] [Indexed: 12/11/2022]
Abstract
Smoking during pregnancy increases the risk of preterm delivery, which in turn necessitates the common use of glucocorticoids to prevent respiratory distress syndrome. Accordingly, there is a substantial population exposed conjointly to fetal nicotine and glucocorticoids (typically dexamethasone). We administered nicotine to pregnant rats throughout gestation, using a regimen (3 mg/kg/day by osmotic minipump) that maintains plasma nicotine levels within the range seen in smokers; on gestational days 17, 18 and 19, we gave 0.2 mg/kg of dexamethasone. We assessed norepinephrine levels in three brain regions (frontal/parietal cortex, brainstem, cerebellum) throughout adolescence, young adulthood and later adulthood, and contrasted the persistent effects with comparable measures in peripheral tissues (heart, liver). In adolescence, males showed initial deficits in the frontal/parietal cortex with either dexamethasone alone or the combined treatment, with resolution to normal by young adulthood; the group exposed to both nicotine+dexamethasone showed subsequent elevations that emerged in full adulthood and persisted through five months of age, an effect not seen with either agent separately. In females, the combined exposure produced an initial deficit that resolved by young adulthood, without any late-emerging changes. We did not see comparable effects in the other brain regions or peripheral tissues. This indicates that nicotine exposure sensitizes the developing brain to the adverse effects of dexamethasone treatment, producing sex-selective changes in innervation and/or activity of specific noradrenergic circuits. The fact that the combined treatment produced greater effects points to potentially worsened neurobehavioral outcomes after pharmacotherapy of preterm labor in the offspring of smokers.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Box 3813 DUMC, Durham, NC, USA.
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28
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Cholinergic influences on cortical development and adult neurogenesis. Behav Brain Res 2011; 221:379-88. [PMID: 21272598 DOI: 10.1016/j.bbr.2011.01.021] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 01/10/2011] [Accepted: 01/13/2011] [Indexed: 11/22/2022]
Abstract
In this review, we focus on immature neurons and their regulation by the cholinergic system, both during cortical development as well as during adult neurogenesis. We discuss various studies that indicate roles for acetylcholine in precursor development and neuronal differentiation. Cholinergic neurons projecting from the basal forebrain innervate the cerebral cortex during critical periods of neuronal development. Acetylcholine stimulation may help to promote a favourable environment for neuronal maturation. Afferents and their cortical target cells interact and are likely to influence each other during the establishment and refinement of connections. Intracortical cholinergic interneurons similarly have a local effect on cortical circuits. Reduced cholinergic innervation during development hence leads to reduced cortical thickness and dendritic abnormalities. Acetylcholine is also likely to play a critical role in neuronal plasticity, as shown in the visual and barrel cortices. Spontaneous nicotinic excitation is also important during a brief developmental window in the first postnatal weeks leading to waves of neural activity, likely to have an effect on neurite extension, target selection and synaptogenesis. In the hippocampus such activity plays a role in the maturation of GABAergic synapses during the developmental shift from depolarizing to hyperpolarizing transmission. The cholinergic system also seems likely to regulate hippocampal neurogenesis in the adult, positively promoting proliferation, differentiation, integration and potentially survival of newborn neurons.
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Shideler KK, Yan J. M1 muscarinic receptor for the development of auditory cortical function. Mol Brain 2010; 3:29. [PMID: 20964868 PMCID: PMC2972260 DOI: 10.1186/1756-6606-3-29] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 10/22/2010] [Indexed: 02/02/2023] Open
Abstract
The sensory cortex is subject to continuous remodelling during early development and throughout adulthood. This process is important for establishing normal brain function and is dependent on cholinergic modulation via muscarinic receptors. Five muscarinic receptor genes encode five unique receptor subtypes (M1-5). The distributions and functions of each subtype vary in central and peripheral systems. In the brain, the M1 receptor is most abundant in the cerebral cortex, where its immunoreactivity peaks transiently during early development. This likely signifies the importance of M1 receptor in the development and maintenance of normal cortical function. Several lines of study have outlined the roles of M1 receptors in the development and plasticity of the auditory cortex. For example, M1-knockout reduces experience-dependent plasticity and disrupts tonotopic mapping in the adult mouse auditory cortex. Further evidence demonstrates a role for M1 in neurite outgrowth and hence determining the structure of cortical neurons. The disruption of tonotopic maps in M1-knockout mice may be linked to alterations in thalamocortical connectivity, because the targets of thalamocortical afferents (layer IV cortical neurons) appear less mature in M1 knockouts. Herein we review the literature to date concerning M1 receptors in the auditory cortex and consider some future directions that will contribute to our understanding.
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Affiliation(s)
- Karalee K Shideler
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
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Bisulli F, Vignatelli L, Naldi I, Licchetta L, Provini F, Plazzi G, Di Vito L, Ferioli S, Montagna P, Tinuper P. Increased frequency of arousal parasomnias in families with nocturnal frontal lobe epilepsy: a common mechanism? Epilepsia 2010; 51:1852-60. [PMID: 20477848 DOI: 10.1111/j.1528-1167.2010.02581.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
PURPOSE Retrospective observations disclosed an overlap between parasomnias and nocturnal frontal lobe epilepsy (NFLE) not only in patients but also in their relatives, suggesting a possible common pathogenetic mechanism. This study aimed to verify whether relatives of patients with NFLE have a higher frequency of parasomnias, namely arousal disorders, and thereby shed light on the still unknown pathophysiologic mechanisms underlying NFLE. METHODS We undertook a case-control family study in which we recruited NFLE probands and healthy controls, matched for age, sex, education, and geographic origin. At least four relatives were included for each proband and control. Each subject underwent a standardized interview, with application of the International Classification of Sleep Disorders-Revised (ICSD-R 2001) minimal criteria to diagnose the lifetime prevalence of the main parasomnias. RESULTS Four hundred fifty-eight individuals were recruited: 33 NFLE probands, 200 relatives of probands, 31 controls, and 194 control relatives. All NFLE probands but one have sporadic NFLE. The lifetime prevalence of the following parasomnias differed in proband relatives versus control relatives: arousal disorders [odds ratio (OR) 4.7, 95% confidence interval (CI) 2.0-11.6; p < 0.001] and nightmares (OR 2.6, 95% CI 1.6-4.2; p < 0.001) were more frequent among NFLE proband relatives. In the secondary analysis comparing NFLE probands to controls, arousal disorders (OR 6.3, 95% CI 1.3-31.7; p = 0.023) and bruxism (OR 5.4, 95% CI 1.3-21.7; p = 0.017) were more frequent among NFLE probands. DISCUSSION The higher frequency of arousal disorders in NFLE families suggests an intrinsic link between parasomnias and NFLE and an abnormal (possibly cholinergic) arousal system as a common pathophysiologic mechanism.
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Affiliation(s)
- Francesca Bisulli
- Department of Neurological Sciences, University of Bologna, Bologna, Italy.
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Mimicking maternal smoking and pharmacotherapy of preterm labor: interactions of fetal nicotine and dexamethasone on serotonin and dopamine synaptic function in adolescence and adulthood. Brain Res Bull 2010; 82:124-34. [PMID: 20211707 DOI: 10.1016/j.brainresbull.2010.02.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 02/24/2010] [Accepted: 02/26/2010] [Indexed: 11/24/2022]
Abstract
Fetal coexposure to nicotine and dexamethasone is common: maternal smoking increases the incidence of preterm delivery and glucocorticoids are the consensus treatment for prematurity. We gave pregnant rats 3mg/kg/day of nicotine throughout gestation, a regimen that reproduces smokers' plasma levels, and then on gestational days 17, 18 and 19, we administered 0.2mg/kg of dexamethasone. We evaluated developmental indices for serotonin (5HT) and dopamine synaptic function throughout adolescence, young adulthood and later adulthood, assessing the brain regions possessing major 5HT and dopamine projections and cell bodies. Males displayed persistent upregulation of 5HT(1A) and 5HT(2) receptors and the 5HT transporter, with a distinct hierarchy of effects: nicotine<dexamethasone<combined treatment. Females showed downregulation of the 5HT(1A) receptor with the same rank order; both sexes displayed presynaptic hyperactivity of 5HT and dopamine pathways as evidenced by increased neurotransmitter turnover. Superimposed on these overall effects, there were significant differences in temporal and regional relationships among the different treatments, often involving effects that emerged later in life, after a period of apparent normality. This indicates that nicotine and dexamethasone do not simply produce an initial neuronal injury that persists throughout the lifespan but rather, they alter the developmental trajectory of synaptic function. The fact that the combined treatment produced greater effects for many parameters points to potentially worse neurobehavioral outcomes after pharmacotherapy of preterm labor in the offspring of smokers.
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Van Kampen JM, Eckman CB. Agonist-induced restoration of hippocampal neurogenesis and cognitive improvement in a model of cholinergic denervation. Neuropharmacology 2009; 58:921-9. [PMID: 20026137 DOI: 10.1016/j.neuropharm.2009.12.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 12/03/2009] [Accepted: 12/08/2009] [Indexed: 10/20/2022]
Abstract
Loss of basal forebrain cholinergic innervation of the hippocampus and severe neuronal loss within the hippocampal CA1 region are early hallmarks of Alzheimer's disease, and are strongly correlated with cognitive status. Various therapeutic approaches involve attempts to enhance neurotransmission or to provide some level of neuroprotection for remaining cells. An alternative approach may involve the generation of new cells to replace those lost in AD. Indeed, a simple shift in the balance between cell generation and cell loss may slow disease progression and possibly even reverse existing cognitive deficits. One potential neurogenic regulator might be acetylcholine, itself, which has been shown to play a critical role in hippocampal development. Here, we report the effects of various cholinergic compounds on indices of hippocampal neurogenesis, demonstrating a significant induction following pharmacological activation of muscarinic M1 receptors, located on hippocampal progenitors in the adult brain. This is the first report that a small-molecule agonist may induce neurogenesis in the hippocampal CA1 region. Furthermore, such treatment reversed deficits in markers of neurogenesis and spatial working memory triggered by cholinergic denervation in a rodent model. This study suggests the use of small molecule, receptor agonists may represent a novel means to trigger the restoration of specific neuronal populations lost to a variety of neurodegenerative disorders, such as Parkinson's, Alzheimer's, Huntington's and Amyotrophic Lateral Sclerosis.
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Slotkin TA, Ryde IT, Seidler FJ. Additive and synergistic effects of fetal nicotine and dexamethasone exposure on cholinergic synaptic function in adolescence and adulthood: Implications for the adverse consequences of maternal smoking and pharmacotherapy of preterm delivery. Brain Res Bull 2009; 81:552-60. [PMID: 19913076 DOI: 10.1016/j.brainresbull.2009.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 11/05/2009] [Accepted: 11/05/2009] [Indexed: 11/17/2022]
Abstract
Maternal smoking contributes to preterm delivery; glucocorticoids are the consensus treatment for prematurity, thus producing fetal coexposure to nicotine and dexamethasone. We administered nicotine to pregnant rats throughout gestation at a dose (3 mg/kg/day) producing plasma levels typical of smokers. Later in gestation, animals received dexamethasone (0.2 mg/kg). We assessed developmental indices for acetylcholine (ACh) synaptic function throughout adolescence, young adulthood and later adulthood, evaluating brain regions possessing major ACh projections and cell bodies; we measured choline acetyltransferase activity, hemicholinium-3 binding to the presynaptic choline transporter and nicotinic ACh receptor binding. In general, nicotine and dexamethasone, alone or in combination, produced regionally-selective increases or decreases in choline acetyltransferase activity but larger, consistent elevations in hemicholinium-3 and nicotinic ACh receptor binding; the patterns were indicative of ACh synaptic hyperactivity. Superimposed on these overall effects, there were significant disparities in temporal and regional relationships among the different treatments, notably involving effects that emerged later in life, after a period of apparent normality. This indicates that nicotine and dexamethasone do not simply produce an initial ACh neuronal injury that then persists throughout the lifespan but rather, they alter the developmental trajectory of ACh function. Most importantly, the combined exposure to nicotine + dexamethasone elicited greater changes than either of the individual exposures, involving both additive and synergistic effects. Our results thus point to potentially worse neurobehavioral outcomes of the pharmacotherapy of preterm labor in the offspring of smokers.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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Slotkin TA, Ryde IT, Wrench N, Card JA, Seidler FJ. Nonenzymatic role of acetylcholinesterase in neuritic sprouting: regional changes in acetylcholinesterase and choline acetyltransferase after neonatal 6-hydroxydopamine lesions. Neurotoxicol Teratol 2009; 31:183-6. [PMID: 19452616 DOI: 10.1016/j.ntt.2008.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acetylcholinesterase (AChE) is postulated to play a nonenzymatic role in the development of neuritic projections. We gave the specific neurotoxin, 6-OHDA to rats on postnatal day (PN) 1, a treatment that destroys noradrenergic nerve terminals in the forebrain while producing reactive sprouting in the brainstem. AChE showed profound decreases in the forebrain that persisted in males over the entire phase of major synaptogenesis, from PN4 through PN21; in the brainstem, AChE was increased. Parallel examinations of choline acetyltransferase, an enzymatic marker for cholinergic nerve terminals, showed a different pattern of 6-OHDA-induced alterations, with initial decreases in both forebrain and brainstem in males and regression toward normal by PN21; females were far less affected. The sex differences are in accord with the greater plasticity of the female brain and its more rapid recovery from neurotoxic injury; our findings indicate that these differences are present well before puberty. These results support the view that AChE is involved in neurite formation, unrelated to its enzymatic role in cholinergic neurotransmission. Further, the results for choline acetyltransferase indicate that early depletion of norepinephrine compromises development of acetylcholine systems, consistent with a trophic role for this neurotransmitter.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina, 27710, USA.
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Slotkin TA, Lassiter TL, Ryde IT, Wrench N, Levin ED, Seidler FJ. Consumption of a high-fat diet in adulthood ameliorates the effects of neonatal parathion exposure on acetylcholine systems in rat brain regions. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:916-22. [PMID: 19590683 PMCID: PMC2702406 DOI: 10.1289/ehp.0800459] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 02/03/2009] [Indexed: 05/08/2023]
Abstract
BACKGROUND Developmental exposure to a wide variety of developmental neurotoxicants, including organophosphate pesticides, evokes late-emerging and persistent abnormalities in acetylcholine (ACh) systems. We are seeking interventions that can ameliorate or reverse the effects later in life. OBJECTIVES We administered parathion to neonatal rats and then evaluated whether a high-fat diet begun in adulthood could reverse the effects on ACh systems. METHODS Neonatal rats received parathion on postnatal days 1-4 at 0.1 or 0.2 mg/kg/day, straddling the cholinesterase inhibition threshold. In adulthood, half the animals were switched to a high-fat diet for 8 weeks. We assessed three indices of ACh synaptic function: nicotinic ACh receptor binding, choline acetyltransferase activity, and hemicholinium-3 binding. Determinations were performed in brain regions comprising all the major ACh projections and cell bodies. RESULTS Neonatal parathion exposure evoked widespread abnormalities in ACh synaptic markers, encompassing effects in brain regions possessing ACh projections and ACh cell bodies. In general, males were affected more than females. Of 17 regional ACh marker abnormalities (10 male, 7 female), 15 were reversed by the high-fat diet. CONCLUSIONS A high-fat diet reverses neurodevelopmental effects of neonatal parathion exposure on ACh systems. This points to the potential for nonpharmacologic interventions to offset the effects of developmental neurotoxicants. Further, cryptic neurodevelopmental deficits evoked by environmental exposures may thus engender a later preference for a high-fat diet to maintain normal ACh function, ultimately contributing to obesity.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Dwyer JB, McQuown SC, Leslie FM. The dynamic effects of nicotine on the developing brain. Pharmacol Ther 2009; 122:125-39. [PMID: 19268688 DOI: 10.1016/j.pharmthera.2009.02.003] [Citation(s) in RCA: 420] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 02/05/2009] [Indexed: 12/25/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) regulate critical aspects of brain maturation during the prenatal, early postnatal, and adolescent periods. During these developmental windows, nAChRs are often transiently upregulated or change subunit composition in those neural structures that are undergoing major phases of differentiation and synaptogenesis, and are sensitive to environmental stimuli. Nicotine exposure, most often via tobacco smoke, but increasingly via nicotine replacement therapy, has been shown to have unique effects on the developing human brain. Consistent with a dynamic developmental role for acetylcholine, exogenous nicotine produces effects that are unique to the period of exposure and that impact the developing structures regulated by acetylcholine at that time. Here we present a review of the evidence, available from both the clinical literature and preclinical animal models, which suggests that the diverse effects of nicotine exposure are best evaluated in the context of regional and temporal expression patterns of nAChRs during sensitive maturational periods, and disruption of the normal developmental influences of acetylcholine. We present evidence that nicotine interferes with catecholamine and brainstem autonomic nuclei development during the prenatal period of the rodent (equivalent to first and second trimester of the human), alters the neocortex, hippocampus, and cerebellum during the early postnatal period (third trimester of the human), and influences limbic system and late monoamine maturation during adolescence.
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Affiliation(s)
- Jennifer B Dwyer
- Department of Pharmacology, Med Surge II, School of Medicine, University of California, Irvine, CA 92697, USA.
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VanDeMark KL, Guizzetti M, Giordano G, Costa LG. The activation of M1 muscarinic receptor signaling induces neuronal differentiation in pyramidal hippocampal neurons. J Pharmacol Exp Ther 2009; 329:532-42. [PMID: 19190235 DOI: 10.1124/jpet.108.150128] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Muscarinic receptors have been proposed to play an important role during brain development by regulating cell survival, proliferation, and differentiation. This study investigated the effect of muscarinic receptor activation on prenatal rat hippocampal pyramidal neuron differentiation and the signal transduction pathways involved in this effect. The cholinergic agonist carbachol, after 24 h in vitro, increased the length of the axon, without affecting the length of minor neurites. Carbachol-induced axonal growth was also observed in pyramidal neurons from the neocortex but not in granule neurons from the cerebellum. The effect of carbachol was mediated by the M(1) subtype of muscarinic receptors. The Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, the two protein kinase C (PKC) inhibitors 3-[1-[3-(dimethylaminopropyl]-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione monohydrochloride (GF109203X) and 2-[8-[(dimethylamino)methyl]-6,7,8,9-tetrahydropyridol[1,2-a]indol-3-yl]-3-(1-methylindol-3-yl)maleimide (Ro-32-0432), and the extracellular signal-regulated kinase (ERK)1/2 inhibitors 2'-amino-3'-methoxyflavone (PD98059) and 1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene (U0126) all blocked carbachol-induced axonal outgrowth. In addition, down-regulation of ERK1/2 with small interfering RNA abolished the neuritogenic effect of carbachol. These data suggest an involvement of Ca(2+), PKC, and ERK1/2 in carbachol-induced axonal growth. Carbachol indeed increased the release of Ca(2+) from intracellular stores and induced PKC and ERK1/2 activation. Additional experiments showed that PKC, but not Ca(2+), is involved in carbachol-induced ERK1/2 activation. Together, these results show that cholinergic stimulation of prenatal hippocampal pyramidal neurons accelerates axonal growth through the induction of Ca(2+) mobilization and the activation of PKC and especially of ERK1/2.
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Affiliation(s)
- Kathryn L VanDeMark
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
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Fragkouli A, Pachnis V, Stylianopoulou F. Sex differences in water maze performance and cortical neurotrophin levels of LHX7 null mutant mice. Neuroscience 2008; 158:1224-33. [PMID: 19095044 DOI: 10.1016/j.neuroscience.2008.11.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/20/2008] [Accepted: 11/13/2008] [Indexed: 01/08/2023]
Abstract
Mice lacking both alleles of the LIM-homeobox gene Lhx7 display dramatically reduced number of forebrain cholinergic neurons. Given the fact that sex differences are consistently observed in forebrain cholinergic function, in the present study we investigated whether the absence of LHX7 differentially affects water maze performance in the two sexes. Herein we demonstrate that LHX7 null mutants display a sex-dependent impairment in water maze, with females appearing more affected than males. Moreover, neurotrophin assessment revealed a compensatory increase of brain-derived neurotrophic factor and neurotrophin 3 in the neocortex of both male and female mutants and an increase of nerve growth factor levels only in the females. Nevertheless, the compensatory increase of cortical neurotrophin levels did not restore cognitive abilities of Lhx7 homozygous mutants. Finally, our analysis revealed that cortical neurotrophin levels correlate negatively with water maze proficiency, indicating that there is an optimal neurotrophin level for successful cognitive performance.
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Affiliation(s)
- A Fragkouli
- Department of Basic Sciences, University of Athens, 11527 Athens, Greece
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Guizzetti M, Moore NH, Giordano G, Costa LG. Modulation of neuritogenesis by astrocyte muscarinic receptors. J Biol Chem 2008; 283:31884-97. [PMID: 18755690 PMCID: PMC2581542 DOI: 10.1074/jbc.m801316200] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 07/22/2008] [Indexed: 11/06/2022] Open
Abstract
Astrocytes have been shown to release factors that have promoting or inhibiting effects on neuronal development. However, mechanisms controlling the release of such factors from astrocytes are not well established. Astrocytes express muscarinic receptors whose activation stimulates a robust intracellular signaling, although the role of these receptors in glial cells is not well understood. Acetylcholine and acetylcholine receptors are present in the brain before synaptogenesis occurs and are believed to be involved in neuronal maturation. The present study was undertaken to investigate whether stimulation of muscarinic receptors in astrocytes would modulate neurite outgrowth in hippocampal neurons. Rat hippocampal neurons, co-cultured with rat cortical astrocytes previously exposed to the cholinergic agonist carbachol, displayed longer neurites. The effect of carbachol in astrocytes was due to the activation of M3 muscarinic receptors. Exposure of astrocytes to carbachol increased the expression of the extracellular matrix proteins fibronectin and laminin-1 in these cells. This effect was mediated in part by an increase in laminin-1 and fibronectin mRNA levels and in part by the up-regulation of the production and release of plasminogen activator inhibitor-1, an inhibitor of the proteolytic degradation of the extracellular matrix. The inhibition of fibronectin activity strongly reduced the effect of carbachol on the elongation of all the neurites, whereas inhibition of laminin-1 activity reduced the elongation of minor neurites only. Plasminogen activator inhibitor-1 also induced neurite elongation through a direct effect on neurons. Taken together, these results demonstrate that cholinergic muscarinic stimulation of astrocytes induces the release of permissive factors that accelerate neuronal development.
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Affiliation(s)
- Marina Guizzetti
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington 98105, USA.
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Buznikov GA, Nikitina LA, Seidler FJ, Slotkin TA, Bezuglov VV, Milosević I, Lazarević L, Rogac L, Ruzdijić S, Rakić LM. Amyloid precursor protein 96-110 and beta-amyloid 1-42 elicit developmental anomalies in sea urchin embryos and larvae that are alleviated by neurotransmitter analogs for acetylcholine, serotonin and cannabinoids. Neurotoxicol Teratol 2008; 30:503-9. [PMID: 18565728 PMCID: PMC2579926 DOI: 10.1016/j.ntt.2008.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 04/28/2008] [Accepted: 05/08/2008] [Indexed: 10/22/2022]
Abstract
Amyloid precursor protein (APP) is overexpressed in the developing brain and portions of its extracellular domain, especially amino acid residues 96-110, play an important role in neurite outgrowth and neural cell differentiation. In the current study, we evaluated the developmental abnormalities caused by administration of exogenous APP(96-110) in sea urchin embryos and larvae, which, like the developing mammalian brain, utilize acetylcholine and other neurotransmitters as morphogens; effects were compared to those of beta-amyloid 1-42 (Abeta42), the neurotoxic APP fragment contained within neurodegenerative plaques in Alzheimer's Disease. Although both peptides elicited dysmorphogenesis, Abeta42 was far more potent; in addition, whereas Abeta42 produced abnormalities at developmental stages ranging from early cleavage divisions to the late pluteus, APP(96-110) effects were restricted to the intermediate, mid-blastula stage. For both agents, anomalies were prevented or reduced by addition of lipid-permeable analogs of acetylcholine, serotonin or cannabinoids; physostigmine, a carbamate-derived cholinesterase inhibitor, was also effective. In contrast, agents that act on NMDA receptors (memantine) or alpha-adrenergic receptors (nicergoline), and that are therapeutic in Alzheimer's Disease, were themselves embryotoxic, as was tacrine, a cholinesterase inhibitor from a different chemical class than physostigmine. Protection was also provided by agents acting downstream from receptor-mediated events: increasing cyclic AMP with caffeine or isobutylmethylxanthine, or administering the antioxidant, a-tocopherol, were all partially effective. Our findings reinforce a role for APP in development and point to specific interactions with neurotransmitter systems that act as morphogens in developing sea urchins as well as in the mammalian brain.
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Affiliation(s)
- Gennady A Buznikov
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710-3813, United States
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Slotkin TA, Bodwell BE, Ryde IT, Levin ED, Seidler FJ. Exposure of neonatal rats to parathion elicits sex-selective impairment of acetylcholine systems in brain regions during adolescence and adulthood. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:1308-14. [PMID: 18941570 PMCID: PMC2569087 DOI: 10.1289/ehp.11451] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 05/19/2008] [Indexed: 05/24/2023]
Abstract
BACKGROUND Organophosphates elicit developmental neurotoxicity through multiple mechanisms other than their shared property as cholinesterase inhibitors. Accordingly, these agents may differ in their effects on specific brain circuits. OBJECTIVES We gave parathion to neonatal rats [postnatal days (PNDs) 1-4], at daily doses of 0.1 or 0.2 mg/kg, spanning the threshold for barely detectable cholinesterase inhibition and systemic effects. METHODS We assessed neurochemical indices related to the function of acetylcholine (ACh) synapses (choline acetyltransferase, presynaptic high-affinity choline transporter, nicotinic cholinergic receptors) in brain regions comprising all the major ACh projections, with determinations carried out from adolescence to adulthood (PNDs 30, 60, and 100). RESULTS Parathion exposure elicited lasting alterations in ACh markers in the frontal/parietal cortex, temporal/occipital cortex, midbrain, hippocampus, and striatum. In cerebrocortical areas, midbrain, and hippocampus, effects in males were generally greater than in females, whereas in the striatum, females were targeted preferentially. Superimposed on this general pattern, the cerebrocortical effects showed a nonmonotonic dose-response relationship, with regression of the defects at the higher parathion dose; this relationship has been seen also after comparable treatments with chlorpyrifos and diazinon and likely represents the involvement of cholinesterase-related actions that mask or offset the effects of lower doses. CONCLUSIONS Neonatal exposure to parathion, at doses straddling the threshold for cholinesterase inhibition, compromises indices of ACh synaptic function in adolescence and adulthood. Differences between the effects of parathion compared with chlorpyrifos or diazinon and the non-monotonic dose-effect relationships reinforce the conclusion that various organophosphates diverge in their effects on neurodevelopment, unrelated to their anticholinesterase actions.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Timofeeva OA, Sanders D, Seemann K, Yang L, Hermanson D, Regenbogen S, Agoos S, Kallepalli A, Rastogi A, Braddy D, Wells C, Perraut C, Seidler FJ, Slotkin TA, Levin ED. Persistent behavioral alterations in rats neonatally exposed to low doses of the organophosphate pesticide, parathion. Brain Res Bull 2008; 77:404-11. [PMID: 18817854 DOI: 10.1016/j.brainresbull.2008.08.019] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2008] [Revised: 08/17/2008] [Accepted: 08/18/2008] [Indexed: 11/26/2022]
Abstract
Although developmental exposures of rats to low levels of the organophosphate pesticides (OPs), chlorpyrifos (CPF) or diazinon (DZN), both cause persistent neurobehavioral effects, there are important differences in their neurotoxicity. The current study extended investigation to parathion (PTN), an OP that has higher systemic toxicity than either CPF or DZN. We gave PTN on postnatal days (PND) 1-4 at doses spanning the threshold for systemic toxicity (0, 0.1 or 0.2 mg/kg/day, s.c.) and performed a battery of emotional and cognitive behavioral tests in adolescence through adulthood. The higher PTN dose increased time spent on the open arms and the number of center crossings in the plus maze, indicating greater risk-taking and overall activity. This group also showed a decrease in tactile startle response without altering prepulse inhibition, indicating a blunted acute sensorimotor reaction without alteration in sensorimotor plasticity. T-maze spontaneous alternation, novelty-suppressed feeding, preference for sweetened chocolate milk, and locomotor activity were not significantly affected by neonatal PTN exposure. During radial-arm maze acquisition, rats given the lower PTN dose committed fewer errors compared to controls and displayed lower sensitivity to the amnestic effects of the NMDA receptor blocker, dizocilpine. No PTN effects were observed with regard to the sensitivity to blockade of muscarinic and nicotinic cholinergic receptors, or serotonin 5HT(2) receptors. This study shows that neonatal PTN exposure evokes long-term changes in behavior, but the effects are less severe, and in some incidences opposite in nature, to those seen earlier for CPF or DZN, findings consistent with our neurochemical studies showing different patterns of effects and less neurotoxic damage with PTN. Our results reinforce the conclusion that low dose exposure to different OPs can have quite different neurotoxic effects, obviously unconnected to their shared property as cholinesterase inhibitors.
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Affiliation(s)
- Olga A Timofeeva
- Department of Psychiatry and Behavioral Sciences, Box #3412, Duke University Medical Center, Durham, NC 27710, USA.
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Slotkin TA, Ryde IT, Levin ED, Seidler FJ. Developmental neurotoxicity of low dose diazinon exposure of neonatal rats: effects on serotonin systems in adolescence and adulthood. Brain Res Bull 2008; 75:640-7. [PMID: 18355640 PMCID: PMC2322865 DOI: 10.1016/j.brainresbull.2007.10.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 10/15/2007] [Accepted: 10/17/2007] [Indexed: 11/17/2022]
Abstract
The developmental neurotoxicity of organophosphate pesticides targets serotonin (5HT) systems, which are involved in emotional and appetitive behaviors. We exposed neonatal rats to daily doses of diazinon on postnatal days 1-4, using doses (0.5 or 2mg/kg) spanning the threshold for barely-detectable cholinesterase inhibition. We then evaluated the effects on 5HT(1A) and 5HT(2) receptors, and on the 5HT transporter in cerebral cortical regions and the brainstem in adolescence through adulthood. Diazinon evoked a lasting deficit in 5HT(1A) receptors in males only, whereas it caused a small but significant increase in 5HT transporters in females; neither effect showed a significant regional selectivity. This pattern differed substantially from that seen in earlier work with another organophosphate, chlorpyrifos, which at pharmacodynamically similar doses spanning the threshold for cholinesterase inhibition, evoked a much more substantial, global upregulation of 5HT receptor expression; with chlorpyrifos, effects on receptors were seen in females, albeit to a lesser extent than in males, and were also regionally distinct. The effects of diazinon were nonmonotonic, showing larger alterations at the lower dose, likely reflecting positive trophic effects of cholinergic stimulation once the threshold for cholinesterase inhibition is exceeded. Our results reinforce the idea that different organophosphates have fundamentally distinct effects on the developmental trajectories of specific neurotransmitter systems, unrelated to their shared action as cholinesterase inhibitors. The effects on 5HT circuits expand the scope of behavioral endpoints that need to be considered in evaluating the developmental neurotoxicity of organophosphates.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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Ruediger T, Bolz J. Neurotransmitters and the development of neuronal circuits. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 621:104-15. [PMID: 18269214 DOI: 10.1007/978-0-387-76715-4_8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the mature brain, neurotransmitters are used for synaptic communication between neurons. But during nervous system development, neurons often express and release transmitters before their axons establish contacts with their target cells. While much is known about the synaptic effects of neurotransmitters, their extrasynaptic effects are less understood. There is increasing evidence that neurotransmitters in the immature nervous system can act as trophic factors that influence different developmental events such as cell proliferation and differentiation. However, more recent work demonstrates that neurotransmitters can also influence the targeting of migrating neurons and growing axons during the formation of neuronal circuits. This chapter will focus on such guidance effects of neurotransmitters during the development of the nervous system. Elucidating extrasynaptic functions during the nervous system development might also provide insights in their potential roles for plasticity and regeneration in the adult nervous system.
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Affiliation(s)
- Tina Ruediger
- Institut für Allgemeine Zoologie und Tierphysiologie, Universitat Jena, Germany
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45
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Montagna P, Provini F, Bisulli F, Tinuper P. Nocturnal epileptic seizures versus the arousal parasomnias. SOMNOLOGIE 2008. [DOI: 10.1007/s11818-008-0333-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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46
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Abstract
The expression of acetylcholinesterase is not restricted to cholinergically innervated tissues and relates to both neurotransmission and multiple biological aspects, including neural development, stress response and neurodegenerative diseases. Therefore, the classical function of acetylcholinesterase has to be distinguished from its non-classical, e.g. enzymatic from non-enzymatic, functions. Here, the roles of acetylcholinesterase in cell adhesion, promoting neurite outgrowth and neural network formation are reviewed briefly, together with potential mechanisms to support these functions. Part of these functions may depend on the structural properties of acetylcholinesterase, for example, protein-protein interactions. Recent findings have revealed that laminin-1 is an interaction partner for acetylcholinesterase. The binding of acetylcholinesterase to this extracellular matrix component may allow cell-to-cell recognition, and also cell signalling via membrane receptors. Studies using monolayer and 3D spheroid retinal cultures, as well as the acetylcholinesterase-knockout mouse, have been instrumental in elaborating the non-classical functions of acetylcholinesterase.
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47
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Arrighi S, Bosi G, Cremonesi F, Domeneghini C. Immunohistochemical study of the pre- and postnatal innervation of the dog lower urinary tract: morphological aspects at the basis of the consolidation of the micturition reflex. Vet Res Commun 2007; 32:291-304. [PMID: 18071920 DOI: 10.1007/s11259-007-9030-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Accepted: 11/21/2007] [Indexed: 11/27/2022]
Abstract
Immunohistochemical studies were performed on male and female bladder and urethra collected from 4 adults dogs and 10 foetal specimens with crown-rump length from 53 to 155 mm (medium-sized breeds, presumptive 38 days of gestation to term). A panel of antisera was tested, including PGP 9.5 to describe the general intramural innervation, ChAT and TH to depict the cholinergic and nor-adrenergic components and NOS1, CGRP, SP, NPY, VIP, SOM, GAL, 5-HT to investigate the possible nitrergic, peptidergic and aminergic ones. A rich cholinergic innervation was present in adult bladder and urethra, along with a lesser number of adrenergic nerves and a small number of nitrergic ones. Either bladder or urethra received numerous CGRP-, SP-, NPY-, VIP-containing nerve fibres which were distributed throughout the muscle layers. All over the lower urinary tract strong to weak ChAT-, CGRP-, SP- and NPY-immunoreactivity was detected in intramural ganglia, in peripheral nerve bundles and around blood vessels. 5-HT-immunoreactive endocrine cells were present in the urethral epithelium. Early foetal organs were supplied only by cholinergic nerve fibres. Few NOS-, CGRP- and SP-ergic components appeared at the end of pregnancy. It can be guessed that sensory mediators such as CGRP and SP increase in postnatal ages while other neuropeptides, such as NPY and VIP, appear only after birth, as the urinary reflex consolidates.
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Affiliation(s)
- S Arrighi
- Department of Veterinary Sciences and Technologies for Food Safety, Laboratory of Anatomy, Faculty of Veterinary Medicine, Via Trentacoste 2, I-20134 Milan, Italy.
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Lin PY, Hinterneder JM, Rollor SR, Birren SJ. Non-cell-autonomous regulation of GABAergic neuron development by neurotrophins and the p75 receptor. J Neurosci 2007; 27:12787-96. [PMID: 18032650 PMCID: PMC6673298 DOI: 10.1523/jneurosci.3302-07.2007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/26/2007] [Accepted: 10/17/2007] [Indexed: 01/12/2023] Open
Abstract
Basal forebrain GABAergic and cholinergic circuits regulate the activity of cholinergic projections to the cortex and hippocampus. Because these projections influence cortical development and function, the development of basal forebrain excitatory and inhibitory neurons is critical for overall brain development. We show that the neurotransmitter phenotype of these neurons is developmentally regulated by neurotrophins and the p75 receptor. Neurotrophins (nerve growth factor and brain-derived neurotrophic factor) increased the number of both cholinergic and GABAergic neurons in neonatal basal forebrain neuron cultures from the region of the medial septum. However, the p75 receptor is required only for neurotrophin-dependent expansion of the GABAergic, not the cholinergic, population. Neurotrophin-induced GABAergic development can be rescued in p75-/- cultures by expression of a p75 rescue construct in neighboring cells or by treatment with medium collected from neurotrophin-treated wild-type cultures. Because p75 is not expressed in basal forebrain GABAergic neurons, this defines a new, non-cell-autonomous mechanism of p75 action in which ligand binding results in release of a soluble factor that modifies neurotrophin responses of nearby neurons. p75 is also required for the maintenance of basal forebrain GABAergic neurons in vivo, demonstrating that p75-mediated interactions between cholinergic and GABAergic neurons regulate the balance of excitatory and inhibitory components of basal forebrain circuits.
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Affiliation(s)
- Pao-Yen Lin
- Department of Biology, Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, and
- Department of Psychiatry, Chang Gung Memorial Hospital–Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, County 831, Taiwan
| | - Jeanine M. Hinterneder
- Department of Biology, Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, and
| | - Sarah R. Rollor
- Department of Biology, Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, and
| | - Susan J. Birren
- Department of Biology, Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, and
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Slotkin TA, Ryde IT, Seidler FJ. Separate or sequential exposure to nicotine prenatally and in adulthood: Persistent effects on acetylcholine systems in rat brain regions. Brain Res Bull 2007; 74:91-103. [PMID: 17683794 DOI: 10.1016/j.brainresbull.2007.05.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 05/16/2007] [Accepted: 05/16/2007] [Indexed: 11/26/2022]
Abstract
Nicotine is a developmental neurotoxicant but the proposed "sensitization-homeostasis" model postulates that even in adulthood nicotine permanently reprograms synaptic function. We administered nicotine to rats throughout gestation or in adulthood (postnatal days PN90-107), simulating plasma levels in smokers, with evaluations on PN105, PN110, PN120, PN130 and PN180. We assessed nicotinic acetylcholine receptor (nAChR) binding, choline acetyltransferase activity, a marker for acetylcholine (ACh) terminals, and hemicholinium-3 (HC3) binding to the choline transporter, an index of ACh presynaptic activity. Prenatal nicotine exposure elicited persistent deficits in HC3 binding in male cerebral cortex and female striatum, but little change in other parameters. Nicotine given in adulthood produced profound nAChR upregulation lasting 2 weeks after discontinuing treatment. Decrements in cerebrocortical and striatal HC3 binding emerged during withdrawal and persisted through PN180, indicative of reduced ACh synaptic activity. Prenatal nicotine did not evoke any major alterations in the response to nicotine given in adulthood. The effects seen here are substantially different from those found previously for nicotine given to adolescent rats, which showed more prolonged nAChR upregulation and profound, widespread and persistent deficits in markers of ACh synaptic function; for adolescents, prenatal nicotine exposure desensitized nAChR responses, exacerbated withdrawal-induced ACh functional deficits, and worsened the long-term outcome. Our results indicate that the effects of nicotine during prenatal or adolescent stages are indeed distinct from the effects in adults, but that even adults show persistent changes after nicotine exposure, commensurate with the sensitization-homeostasis model. These effects may contribute to lifelong vulnerability to readdiction.
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Affiliation(s)
- Theodore A Slotkin
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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Bartzokis G. Acetylcholinesterase inhibitors may improve myelin integrity. Biol Psychiatry 2007; 62:294-301. [PMID: 17070782 DOI: 10.1016/j.biopsych.2006.08.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 07/28/2006] [Accepted: 08/21/2006] [Indexed: 12/27/2022]
Abstract
Recent clinical trials have revealed that cholinergic treatments are efficacious in a wide spectrum of neuropsychiatric disorders that span the entire human lifespan and include disorders without cholinergic deficits. Furthermore, some clinical and epidemiological data suggest that cholinergic treatments have disease modifying/preventive effects. It is proposed that these observations can be usefully understood in a myelin-centered model of the human brain. The model proposes that the human brain's extensive myelination is the central evolutionary change that defines our uniqueness as a species and our unique vulnerability to highly prevalent neuropsychiatric disorders. Within the framework of this model the clinical, biochemical, and epidemiologic data can be reinterpreted to suggest that nonsynaptic effects of cholinergic treatments on the process of myelination and myelin repair contributes to their mechanism of action and especially to their disease modifying/preventive effects. The ability to test the model in human populations with safe and noninvasive imaging technologies makes it possible to undertake novel clinical trial efforts directed at primary prevention of some of the most prevalent and devastating of human disorders.
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Affiliation(s)
- George Bartzokis
- Department of Neurology, The Laboratory of Neuroimaging in the Division of Brain Mapping, The David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095-1769, USA.
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