Methylmercury (MeHg) intoxication is a global health concern. Although MeHg neurotoxicity is well-recognized, less is known about MeHg's effects on metabolism. In this study, we evaluated MeHg intoxication (20mg/L in drinking water for 20 days) effects on liver and epididymal white fat (EWF) in young ApoE knockout (ko) and wild-type mice. The former is well-known to show spontaneous dyslipidemia. Hg levels in hair, liver, and EWF were measured to assess the degree of MeHg exposure. We also evaluated body weight gain, plasma triglycerides, total cholesterol levels, and liver injury by assessing steatosis score, AST, ALT, SOD, and TBAR levels. To evaluate EWF, we analyzed mean wet weight and adipocyte diameter, plasma leptin levels and metabolomics. Hg levels were markedly higher among intoxicated mice. ApoE ko mice showed higher Hg in the hair but lower levels in the liver and EWF than wild-type controls. Among wild-type mice, MeHg compromised weight gain and increased liver TBAR levels compared to non-challenged controls. Among non-intoxicated mice, ApoE deficiency significantly increased triglyceride, total cholesterol, and liver transaminases with reduced EWF wet weight, hepatic SOD, and plasma leptin levels. MeHg accumulation together with ApoE deficiency elevated total cholesterol, triglycerides, hepatic transaminases, and TBARS. We found distinct EWF metabolite activity in different scenarios of ApoE deficiency and MeHg intoxication, highlighting increased cardiovascular risk especially when both challenges occur. Further studies are required to elucidate the underlying mechanisms involved in these effects and the target nutritional interventions in most need to ameliorate them.

Keywords: oligozoospermia; male infertility; epididymis; scrotal exploration; scrotal ultrasound; partial epididymal obstruction

Prolonged ethanol (EtOH) consumption is associated with male infertility with a decreased spermatogenesis rate as one cause. Defective maturation and development of sperm during their storage in the cauda epididymis and transit in the seminal vesicle can be another cause, possibly occurring before the drastic spermatogenesis disruption. Herein, we demonstrated that the cauda epididymis and seminal vesicle of rats, orally fed with EtOH under a regimen that spermatogenesis was still ongoing, showed histological damage, including lesion and decreased height of the epithelial cells, and increased collagen fibers in the muscle layer, which implicated fibrosis. Lipid peroxidation (shown by malondialdehyde (MDA) levels) was observed, indicating that reactive oxygen species (ROS) was produced along with acetaldehyde during EtOH metabolism by CYP2E1. MDA, acetaldehyde and other lipid peroxidation products could further damage cellular components of the cauda epididymis and seminal vesicle and this was supported by increased apoptosis (shown by TUNEL assay and caspase 9/caspase 3 expression) in these two tissues of EtOH-treated rats. Consequently, functionality of the cauda epididymis and seminal vesicle in EtOH-treated rats was impaired, as demonstrated by decreases in 1H NMR-analyzed metabolites (e.g., carnitine, fructose), which were important for sperm development, metabolism and survival in their lumen.