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Nascimento TS, Pinto DV, Dias RP, Raposo RS, Nunes PIG, Roque CR, Santos FA, Andrade GM, Viana JL, Fostier AH, Sussulini A, Alvarez-Leite JI, Fontes-Ribeiro C, Malva JO, Oriá RB. Chronic Methylmercury Intoxication Induces Systemic Inflammation, Behavioral, and Hippocampal Amino Acid Changes in C57BL6J Adult Mice. Int J Mol Sci 2022; 23:13837. [PMID: 36430321 PMCID: PMC9697706 DOI: 10.3390/ijms232213837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 11/12/2022] Open
Abstract
Methylmercury (MeHg) is highly toxic to the human brain. Although much is known about MeHg neurotoxic effects, less is known about how chronic MeHg affects hippocampal amino acids and other neurochemical markers in adult mice. In this study, we evaluated the MeHg effects on systemic lipids and inflammation, hippocampal oxidative stress, amino acid levels, neuroinflammation, and behavior in adult male mice. Challenged mice received MeHg in drinking water (2 mg/L) for 30 days. We assessed weight gain, total plasma cholesterol (TC), triglycerides (TG), endotoxin, and TNF levels. Hippocampal myeloperoxidase (MPO), malondialdehyde (MDA), acetylcholinesterase (AChE), amino acid levels, and cytokine transcripts were evaluated. Mice underwent open field, object recognition, Y, and Barnes maze tests. MeHg-intoxicated mice had higher weight gain and increased the TG and TC plasma levels. Elevated circulating TNF and LPS confirmed systemic inflammation. Higher levels of MPO and MDA and a reduction in IL-4 transcripts were found in the hippocampus. MeHg-intoxication led to increased GABA and glycine, reduced hippocampal taurine levels, delayed acquisition in the Barnes maze, and poor locomotor activity. No significant changes were found in AChE activity and object recognition. Altogether, our findings highlight chronic MeHg-induced effects that may have long-term mental health consequences in prolonged exposed human populations.
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Affiliation(s)
- Tyciane S. Nascimento
- Neuroscience and Behavior Laboratory, Drug Research and Development Center, Federal University of Ceará, Fortaleza 60430-275, Brazil
| | - Daniel V. Pinto
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Ronaldo P. Dias
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Ramon S. Raposo
- Experimental Biology Core, Health Sciences Center, University of Fortaleza, Fortaleza 60812-020, Brazil
| | - Paulo Iury G. Nunes
- Natural Products Laboratory, Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Cássia R. Roque
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Flávia A. Santos
- Natural Products Laboratory, Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Geanne M. Andrade
- Neuroscience and Behavior Laboratory, Drug Research and Development Center, Federal University of Ceará, Fortaleza 60430-275, Brazil
| | - José Lucas Viana
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13083-862, Brazil
| | - Anne H. Fostier
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13083-862, Brazil
| | - Alessandra Sussulini
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13083-862, Brazil
| | - Jacqueline I. Alvarez-Leite
- Laboratory of Atherosclerosis and Nutritional Biochemistry, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Carlos Fontes-Ribeiro
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Institute of Pharmacology and Experimental Therapeutics and Center for Innovative Biomedicine and Biotechnology (CIBB), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - João O. Malva
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Institute of Pharmacology and Experimental Therapeutics and Center for Innovative Biomedicine and Biotechnology (CIBB), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Reinaldo B. Oriá
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
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Kalisch BE, Racz WJ. The effects of methylmercury on endogenous dopamine efflux from mouse striatal slices. Toxicol Lett 1996; 89:43-9. [PMID: 8952710 DOI: 10.1016/s0378-4274(96)03787-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The present study investigated the effects of in vitro methylmercury (MeHg) exposure on endogenous dopamine (DA) efflux from mouse striatal slices. MeHg produced a concentration-dependent increase in the spontaneous efflux of DA which was independent of the availability of Ca2+ in the superfusion medium. The Ca(2+)-dependent K(+)-evoked release of DA was significantly enhanced by 50 and 100 microM MeHg. This increase could not be solely accounted for by the MeHg-induced increased in spontaneous DA efflux. The K(+)-stimulated efflux of DA was enhanced by MeHg in both the presence and absence of Ca2+ in the superfusion medium, suggesting that under depolarizing conditions, DA efflux induced by MeHg has a Ca(2+)-independent component. The alterations in DA efflux occurred at concentrations of MeHg previously found in the CNS of animals exhibiting symptoms of MeHg intoxication suggesting that alterations in DA neurotransmission in the striatum may contribute to the symptoms of MeHg toxicity.
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Affiliation(s)
- B E Kalisch
- Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario, Canada
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Inouye M, Kajiwara Y, Hirayama K. Dose- and sex-dependent alterations in mercury distribution in fetal mice following methylmercury exposure. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 1986; 19:425-35. [PMID: 3772988 DOI: 10.1080/15287398609530940] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Methylmercuric chloride was orally given to inbred C57BL/6N mice on d 13 of pregnancy at doses of 2.5, 5, 10, and 20 mg/kg. Animals were sacrificed on each of d 14-18 of pregnancy, and mercury levels in the brain, liver, and kidney of both the fetus and dam were determined. The dose effect on the time course of mercury accumulation in the brain was observed both in the fetus and dam; after the higher doses administered, the brain mercury reached the highest concentration later than it did after the lower doses. In addition, the mercury concentration in the fetal brain was disproportionately higher after a dose of 20 mg/kg, which was toxic in the fetus since the weight of the brain was reduced. The concentration in the fetal brain was 1.6-4.9 times higher than in the maternal brain. The sex difference of fetuses in mercury levels was observed in the brain after a dose of 2.5 mg/kg, in which mercury concentration was higher in females than in males. This corresponded to the previously reported difference in adult mice and rats. However, the sex difference was not seen after doses of 5, 10, or 20 mg/kg.
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Kajiwara Y, Inouye M. Effects of methylmercury and mercuric chloride on preimplantation mouse embryos in vivo. TERATOLOGY 1986; 33:231-7. [PMID: 3738818 DOI: 10.1002/tera.1420330210] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This report compares the effects of methylmercuric chloride (MMC) and mercuric chloride (MC) on the development of mouse preimplantation embryos in vivo. Female mice were injected with a single intravenous dose of 0.5-20.0 mg Hg/kg MMC or 0.5-2.5 mg Hg/kg MC on day 0 of gestation. The embryos were recovered by flushing excised oviduct and uterus on day 3.5 of pregnancy, and were examined for abnormalities. In the groups treated with doses of 0.5 and 1.0 mg Hg/kg of both compounds, the rates of abnormal embryos were not significantly different from that in the control group. The 50% effective dose of MMC was twice as great as that of MC. With increasing dose, the difference became more obvious; the 80% effective doses differed by a factor of ten. The body weight of dams decreased in terms of the dose of mercury in MC-treated groups, but did not vary in MMC-treated groups. The sensitive developmental stage for mercury toxicities could not be determined clearly, although the high sensitivity was reported in the blastocyst stage in vitro. The embryos treated in vivo were less sensitive than those reported in vitro.
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