Pharmacokinetic and Genomic Effects of Arsenite in Drinking Water on Mouse Lung in a 30-Day Exposure

Dysregulation of Sqstm1, mitophagy, and apoptotic genes in chronic exposure to arsenic and high-fat diet (HFD)

Arsenic (As) is a toxic and hazardous metalloid. Unfortunately, its presence in drinking water together with wrong nutritional patterns is associated with an increase in the occurrence of metabolic disorders in young people. Degradation of mitochondria is presented by a specific form of autophagy called mitophagy which is an important landmark leading to apoptosis during lipotoxicity. Lipotoxicity and cellular toxicity due to arsenic intake can lead to changes in mitophagy and apoptosis. The protein derived from SQSTM1 gene, also called p62, plays an important role in energy homeostasis in the liver, and it can contribute to the regulation of autophagic responses given its effect on signaling of mTOR, MAPK, and NF-KB. Consequently, changes in Sqstm1, mitophagy (BNIP3), and apoptotic (caspase 3) genes in the livers of NMRI mice were examined with the use of real-time RT-PCR Array followed by exposure to an environmentally relevant and negligible cytotoxic concentration of arsenite (50 ppm) in drinking water while being fed with a high-fat diet (HFD) or low-fat diet (LFD) for 20 weeks (LFD-As and HFD-As groups). While LFD-As and HFD groups showed a decrease in BNIP3 expression, a significant increase was observed in the HFD-As group. P62 gene showed downregulation in LFD-As and HFD groups, and upregeneration was observed in the HFD-As group. Caspase 3 showed increased expression as the key factor associated with apoptotic liver cell death in the three groups, with the highest value in HFD-As group. Overall, the changes observed in the expression of Sqstm1, BNIP3, and caspase 3 in this study can be related to the level of liver damage caused by exposure to arsenic and HFD and probably, BNIP3 pro-apoptotic protein is associated with an increased cell death due to HFD and As.

Evaluation of Diabetogenic Mechanism of High Fat Diet in Combination with Arsenic Exposure in Male Mice

Obesity is a main reason of type 2 diabetes and also chronic exposure to arsenic (As) can produce diabetic symptoms. In previous studies, the association between high-fat diet and arsenic in the incidence of diabetes was found, but the role of beta cells activity, liver mitochondrial oxidative stress, and hepatic enzymes (leptin, adiponectin and beta amylase) was unclear. Thus, present study was conducted to evaluate the diabetogenic mechanism of arsenic followed by concomitant administration of high-fat diet (HFD) in male mice. In this experimental study, the mice consumed with HFD or low-fat diet (LFD) while exposed to As 25 or 50 ppm in drinking water for 20 weeks. At the end of experiments, hyperglycemia, insulin resistance variables, lipid profile, hepatic enzymes, liver mitochondrial oxidative stress, islet insulin secretion, liver, and pancreas histopathology were evaluated in all mice by their own methods. Control HFD fed mice showed a significant increase in FBG, OGTT, HOMA-IR, ITT, lipid profile, leptin, β-amylase, liver mitochondrial oxidative stress, hepatic enzymes and decreased FPI, HOMA-β, adiponectin, and islet insulin secretion or content. However, exposure to HFD concomitant with Arsenic revealed an impressive reduction in FBG, FPI, HOMA-IR, HOMA-β, ITT, lipid profile, and islet insulin secretion or content. This exposure enhanced OGTT, leptin, adiponectin, liver mitochondrial oxidative stress, and hepatic enzymes. In conclusion, HFD and arsenic concomitant administration induced impairment of OGTT and islet insulin secretion or content through the mitochondrial oxidative stress.