Methylmercury exposure for 14 days (short-term) produces behavioral and biochemical changes in mouse cerebellum, liver, and serum

ABSTRACT

Various studies on methylmercury (MeHg)-induced toxicity focused on the central nervous system (CNS) as a primary target. However, MeHg-mediated toxicity is related to metallic interaction with electrophilic groups, which are not solely restricted to the CNS, but these reactive groups are present ubiquitously in several systems/organs. The aim of this study was thus to examine MeHg-induced systemic toxicity in mice using a standardized neurotoxicology testing exposure model to measure cerebellar neurotoxicity by determining biochemical and behavioral parameters in the cerebellum. After 2 weeks exposure to MeHg (40 µg/ml; diluted in drinking water; ad libitum), adult male Swiss mice showed a marked motor impairment characteristic of cerebellar toxicity as noted in the following tests: rotarod, beam walking, pole, and hind limb clasping. MeHg treatment resulted in Hg deposition in the cerebellum as well as reduction in cerebellar weight, glutathione peroxidase (GPx) activity, and interleukin (IL)-6 levels. MeHg ingestion increased cerebellar glutathione reductase (GR) activity and brain-derived neurotrophic factor (BDNF) levels. In addition to cerebellar toxicity, MeHg treatment also elevated total and non-high density lipoprotein (non-HDL) cholesterol levels, as well as serum aspartate transaminase (AST) and alanine transaminase (ALT) enzymatic activities, systemic parameters. Increased liver weight and reduced serum urea levels were also noted in MeHg-exposed mice. Taken together, our findings demonstrated that a well-standardized exposure protocol to examine MeHg-induced neurotoxicity also produced systemic toxicity in mice, which was characterized by changes in markers of hepatic function as well as serum lipid homeostasis.

Funding

This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina (FAPESC), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil.

Conflict of interest

The authors declare that there are no conflicts of interest.

Additional information

Funding

This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina (FAPESC), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil.