1
|
Canadian Arctic Contaminants and Their Effects on the Maternal Brain and Behaviour: A Scoping Review of the Animal Literature. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17030926. [PMID: 32024308 PMCID: PMC7038163 DOI: 10.3390/ijerph17030926] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 12/15/2022]
Abstract
Background: Environmental toxicants such as methylmercury, polychlorinated biphenyls, and organochlorine pesticides are potentially harmful pollutants present in contaminated food, soil, air, and water. Exposure to these ecologically relevant toxicants is prominent in Northern Canadian populations. Previous work focused on toxicant exposure during pregnancy as a threat to fetal neurodevelopment. However, little is known about the individual and combined effects of these toxicants on maternal health during pregnancy and post-partum. Methods: A scoping review was conducted to synthesize the current knowledge regarding individual and combined effects of methylmercury, polychlorinated biphenyls, and organochlorine pesticides on maternal behaviour and the maternal brain. Relevant studies were identified through the PubMed, Embase, and Toxline databases. Literature involving animal models and one human cohort were included in the review. Results: Research findings indicate that exposures to these environmental toxicants are associated with neurochemical changes in rodent models. Animal models provided the majority of information on toxicant-induced alterations in maternal care behaviours. Molecular and hormonal changes hypothesized to underlie these alterations were also addressed, although studies assessing toxicant co-exposure were limited. Conclusion: This review speaks to the limited knowledge regarding effects of these persistent organic pollutants on the maternal brain and related behavioural outcomes. Further research is required to better comprehend any such effects on maternal brain and behaviour, as maternal care is an important contributor to offspring neurodevelopment.
Collapse
|
2
|
Reardon AJF, Karathra J, Ribbenstedt A, Benskin JP, MacDonald AM, Kinniburgh DW, Hamilton TJ, Fouad K, Martin JW. Neurodevelopmental and Metabolomic Responses from Prenatal Coexposure to Perfluorooctanesulfonate (PFOS) and Methylmercury (MeHg) in Sprague-Dawley Rats. Chem Res Toxicol 2019; 32:1656-1669. [PMID: 31340646 DOI: 10.1021/acs.chemrestox.9b00192] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Methylmercury (MeHg) and perfluorooctanesulfonate (PFOS) are major contaminants of human blood that are both common in dietary fish, thereby raising questions about their combined impact on human development. Here, pregnant Sprague-Dawley rats ingested a daily dose, from gestational day 1 through to weaning, of either 1 mg/kg bw PFOS (PFOS-only), 1 mg/kg MeHg (MeHg-only), a mixture of 0.1 mg/kg PFOS and 1 mg/kg MeHg (Low-Mix), or of 1 mg/kg of PFOS and 1 mg/kg MeHg (High-Mix). Newborns were monitored for physical milestones and reflexive developmental responses, and in juveniles the spontaneous activity, anxiety, memory, and cognition were assessed. Targeted metabolomics of 199 analytes was applied to sectioned brain regions of juvenile offspring. Newborns in the High-Mix group had decreased weight gain as well as delayed reflexes and innate behavioral responses compared to controls and individual chemical groups indicating a toxicological interaction on early development. In juveniles, cumulative mixture effects increased in a dose-dependent manner in tests of anxiety-like behavior. However, other developmental test results suggested antagonism, as PFOS-only and MeHg-only juveniles had increased hyperactivity and thigmotaxic behavior, respectively, but fewer effects in Low-Mix and High-Mix groups. Consistent with these behavioral observations, a pattern of antagonism was also observed in neurochemicals measured in rat cortex, as PFOS-only and MeHg-only juveniles had altered concentrations of metabolites (e.g., lipids, amino acids, and biogenic amines), while no changes were evident in the combined exposures. The cortical metabolites altered in PFOS-only and MeHg-only exposed groups are involved in inhibitory and excitatory neurotransmission. These proof-of-principle findings at relatively high doses indicate the potential for toxicological interaction between PFOS and MeHg, with developmental-stage specific effects. Future mixture studies at lower doses are warranted, and prospective human birth cohorts should consider possible confounding effects from PFOS and mercury exposure on neurodevelopment.
Collapse
Affiliation(s)
- Anthony J F Reardon
- Department of Laboratory Medicine and Pathology , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
| | - Jacqueline Karathra
- Department of Laboratory Medicine and Pathology , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
| | - Anton Ribbenstedt
- Department of Environmental Science and Analytical Chemistry (ACES) , Stockholm University , Stockholm SE-11418 , Sweden
| | - Jonathan P Benskin
- Department of Environmental Science and Analytical Chemistry (ACES) , Stockholm University , Stockholm SE-11418 , Sweden
| | - Amy M MacDonald
- Alberta Centre for Toxicology , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
| | - David W Kinniburgh
- Alberta Centre for Toxicology , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
| | - Trevor J Hamilton
- Department of Psychology , MacEwan University , Edmonton , Alberta T5J 4S2 , Canada
| | - Karim Fouad
- Department of Physical Therapy , University of Alberta , Edmonton , Alberta T6G 2G4 , Canada
| | - Jonathan W Martin
- Department of Laboratory Medicine and Pathology , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada.,Department of Environmental Science and Analytical Chemistry (ACES) , Stockholm University , Stockholm SE-11418 , Sweden
| |
Collapse
|
3
|
Enayah SH, Vanle BC, Fuortes LJ, Doorn JA, Ludewig G. PCB95 and PCB153 change dopamine levels and turn-over in PC12 cells. Toxicology 2017; 394:93-101. [PMID: 29233657 DOI: 10.1016/j.tox.2017.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 11/10/2017] [Accepted: 12/06/2017] [Indexed: 10/18/2022]
Abstract
Polychlorinated biphenyls (PCB) exposure at low chronic levels is a significant public health concern. Animal and epidemiological studies indicate that low PCB body burden may cause neurotoxicity and be a risk factor for neurodegenerative diseases. In the current study, we measured the ability of two non-dioxin like PCBs, 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) and 2,2'3,5',6-pentachlorobiphenyl (PCB95), to alter dopamine (DA) levels and metabolism using the dopaminergic PC12 cell line. Our hypothesis is that treatment of PC12 cells with non-toxic concentrations of PCB153 or PCB95 for 12 and 24 h will have different effects due to different congener structures. Levels of DA and of 3,4-dihydroxyphenylacetaldehyde (DOPAL), 3, 4-dihyroxylphenylethanol (DOPET), and 3,4-dihyroxylphenylacetic acid (DOPAC) metabolite, gene expression of the dopamine synthesis enzyme tyrosine hydroxylase (TH) and the vesicular monoamine transporter (VMAT2), and gene expression of the anti-oxidant enzymes Cu/Zn and Mn superoxide oxidase (Cu/ZnSOD, MnSOD), glutathione peroxidase (GPx) and catalase were determined. PCB153 decreased intracellular and extracellular levels of DA after 12 h exposure and this was consistent with an increase in DA metabolites. After 24 h, the level of DA in medium increased compared to the control. In contrast, PCB95 exposure increased the intracellular DA level and decreased DA in medium consistent with a down-regulation of VMAT2 expression at 12 h. After 24 h exposure, PCB95 increased DA levels in media. Expression of TH mRNA increased slightly following 12 h but not at 24 h exposure. MnSOD mRNA increased up to 6-7 fold and Cu/ZnSOD increased less than two-fold after treatment with both congeners. Catalase expression was up-regulated following 24 h exposure to PCB153 and PCB95, but GPx expression was down-regulated after 12 h exposure to PCB95 only. These results suggest that PCB153 and PCB95 are neurotoxic and affect DA turnover with structure-dependent differences between these two congeners.
Collapse
Affiliation(s)
- Sabah H Enayah
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, United States
| | - Brigitte C Vanle
- Department of Pharmaceutical Sciences & Experimental Therapeutics, University of Iowa, United States
| | - Laurence J Fuortes
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, United States; Department of Occupational & Environmental Health, University of Iowa, United States
| | - Jonathan A Doorn
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, United States; Department of Pharmaceutical Sciences & Experimental Therapeutics, University of Iowa, United States
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, United States; Department of Occupational & Environmental Health, University of Iowa, United States.
| |
Collapse
|
4
|
Garcia MS, Constantino DHJ, Silva APG, Perobelli JE. Fish pollutants MeHg and Aroclor cause permanent structural damage in male gonads and kidneys after prepubertal exposure. Int J Exp Pathol 2016; 97:360-368. [PMID: 27917541 PMCID: PMC5206816 DOI: 10.1111/iep.12200] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 08/08/2016] [Indexed: 12/29/2022] Open
Abstract
This study investigated whether or not prepubertal exposure to the fish contaminants methylmercury (MeHg) and the polychlorinated bisphenol Aroclor in low doses interferes with the histomorphometry of the testes, epididymis, liver and kidneys in rats. Wistar male rats, 21 days old, were allocated into the following: control (n = 17, received corn oil), MeHg (n = 17, received MeHg at 0.5 mg/kg/day), Aroclor (n = 17, received Aroclor at 1.0 mg/kg/day), low mix (n = 18, received MeHg at 0.05 mg/kg/day and Aroclor at 0.1 mg/kg/day), high mix (n = 18, received MeHg at 0.5 mg/kg/day and Aroclor at 1.0 mg/kg/day). Dosing continued from post natal day (PND) 23 to 53, by gavage. Euthanasia was performed on PND 53; or, after an interval of 62 days without exposure to chemicals, on PND 115. The degree of maturation of the seminiferous epithelium was delayed in chemical-exposed groups and testicular interstitial oedema was observed at adulthood. The pattern of male gonad organization was changed in the Aroclor group on PND 53 and in all treated groups at adulthood. The animals from Aroclor, low mix and high mix groups showed a reduction in the number of Sertoli cells. Histological evidence of renal injury was observed in all chemical-exposed groups in both ages. A probable target for MeHg and Aroclor in the reproductive system was Sertoli cells, in which possible dysfunctions could be linked to the other testicular alterations. Curiously, the main deleterious effects were late outcomes, along with the absence of synergistic interaction of MeHg and Aroclor in the parameters investigated. In conclusion, fish pollutants MeHg and Aroclor caused permanent structural damage in male gonads and kidneys after prepubertal exposure, without showing clear chemical interactions.
Collapse
Affiliation(s)
- Mariana S. Garcia
- Central de Laboratórios de Ciência e Tecnologia AmbientalUniversidade Sagrado Coração, USCBauruSão PauloBrazil
| | - Dulce Helena J. Constantino
- Central de Laboratórios de Ciência e Tecnologia AmbientalUniversidade Sagrado Coração, USCBauruSão PauloBrazil
| | - Ana P. G. Silva
- Programa de Pós‐Gradução Interdisciplinar em Ciências da SaúdeUniversidade Federal de São Paulo, Campus Baixada SantistaSantosSão PauloBrazil
| | - Juliana E. Perobelli
- Departamento de Ciências do MarUniversidade Federal de São Paulo, Campus Baixada SantistaSantosSão PauloBrazil
| |
Collapse
|
5
|
Wu J, Cheng G, Lu Z, Wang M, Tian J, Bi Y. Effects of Methyl Mercury Chloride on Rat Hippocampus Structure. Biol Trace Elem Res 2016; 171:124-30. [PMID: 26358766 PMCID: PMC4832005 DOI: 10.1007/s12011-015-0492-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 08/21/2015] [Indexed: 12/02/2022]
Abstract
The objective of this study is to investigate the impacts of Methyl Mercury Chloride (MMC) on cognitive functions and ultrastructural changes of hippocampus in Sprague Dawley (SD) rats. Thirty healthy 20-day-old male SD rats weighing 30-40 g were randomly divided into three groups to receive daily injections. Two different dose levels were used: 4 mg/kg as high dose (H-MMC) and 2 mg/kg as low dose (L-MMC).The control group received 4 mg/kg saline solution (N-NaCl). After daily subcutaneous injection for 50 days, 6-day Morris water maze tests were used to assess the learning and memory functions of the rats. After a 5-day continuous training, spatial probe tests were conducted of times and paths crossing to the target quadrant on the 6th day. After the rats were euthanized, their hippocampus sections were stained with hematoxylin and eosin and analyzed under bothoptical microscope and electron microscope. The time H-MMC group spent in finding platform was significantly longer as compared toN-NaCl group on day 2 to day 5 and L-MMC group on day 4 to day 5. The number of crossing times of H-MMC group to the target quadrant was 0.63 ± 0.74, which is much lower than C-NaCl group (3.13 ± 1.56) with P value <0.05. No statistically significant difference in crossing times was found between L-MMC and C-NaCl groups. For H-MMC group, decreasing number of neurons and disorganized nerve cells were examined under light microscope. Swelling and dissolution of Golgi complex were examined under electron microscope, along with endoplasmic reticulum expansion and cytoplasmic edema. Mild cytoplasmic edema was found in L-MMC group. MMC can cause cognitive impairment in terms of learning and memory in SD rats. Additionally, it can also cause changes in the ultrastructure of neurons and morphological changes in the hippocampus, causing significant damage.
Collapse
Affiliation(s)
- Jingwei Wu
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Department of Radiology, Hainan Provincial Nongken Hospital, Haikou, China
| | - Guangyuan Cheng
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Zhiyan Lu
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China.
| | - Mingyue Wang
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jianying Tian
- Department of Anatomy, Ningxia Medical University, Yinchuan, China
| | - Yongyi Bi
- School of Public Health, Wuhan University, Wuhan, China
| |
Collapse
|
6
|
Lu Z, Wu J, Cheng G, Tian J, Lu Z, Bi Y. Methylmercury chloride damage to the adult rat hippocampus cannot be detected by proton magnetic resonance spectroscopy. Neural Regen Res 2014; 9:1616-20. [PMID: 25368649 PMCID: PMC4211204 DOI: 10.4103/1673-5374.141789] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2014] [Indexed: 11/04/2022] Open
Abstract
Previous studies have found that methylmercury can damage hippocampal neurons and accordingly cause cognitive dysfunction. However, a non-invasive, safe and accurate detection method for detecting hippocampal injury has yet to be developed. This study aimed to detect methylmercury-induced damage on hippocampal tissue using proton magnetic resonance spectroscopy. Rats were given a subcutaneous injection of 4 and 2 mg/kg methylmercury into the neck for 50 consecutive days. Water maze and pathology tests confirmed that cognitive function had been impaired and that the ultrastructure of hippocampal tissue was altered after injection. The results of proton magnetic resonance spectroscopy revealed that the nitrogen-acetyl aspartate/creatine, choline complex/creatine and myoinositol/creatine ratio in rat hippocampal tissue were unchanged. Therefore, proton magnetic resonance spectroscopy can not be used to determine structural damage in the adult rat hippocampus caused by methylmercury chloride.
Collapse
Affiliation(s)
- Zhiyan Lu
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei Province, China
| | - Jinwei Wu
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei Province, China ; Department of Radiology, Hainan Provincial Nongken Hospital, Haikou, Hainan Province, China
| | - Guangyuan Cheng
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei Province, China
| | - Jianying Tian
- Department of Anatomy, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, China
| | - Zeqing Lu
- School of Public Health, University of Minnesota, Minnesota, MN, USA
| | - Yongyi Bi
- School of Public Health, Wuhan University, Wuhan, Hubei Province, China
| |
Collapse
|