The thyroid is one of the major endocrine glands that contribute to body and fat metabolism. The present study evaluated the effects of combined exposure to chronic high-fat diet (HFD) and arsenic on thyroid function and lipid profile. In this experimental study, 72 male Naval Medical Research Institute mice were divided into six groups and fed HFD or low-fat diet (LFD) while being exposed to 25 or 50 ppm of arsenic in drinking water for 20 weeks. After 24 h of the last experimental day, blood samples were collected for hormonal and biochemical measurements. The data indicated that exposure to HFD alone increased the levels of triiodothyronine (T3), thyroid-stimulating hormone (TSH), leptin, lipid profile, reactive oxygen species (ROS), and malondialdehyde (MDA) and decreased the levels of high-density lipoprotein, albumin, adiponectin, and glutathione sulfhydryl reductase (GSH), whereas exposure to arsenic alone decreased the levels of T3 and GSH and increased the levels of TSH, leptin, ROS, MDA, and T4/T3 ratio compared to those in the control LFD group. Furthermore, concomitant administration of HFD and arsenic decreased the lipid profile and levels of T4, albumin, total protein, T3, and GSH and increased the levels of TSH, adiponectin, leptin, ROS, MDA, and T4/T3 ratio compared to those in the control LFD or HFD group. In conclusion, combined exposure to HFD and arsenic induced hypothyroidism via reduction of thyroid hormones and enhancement of plasma TSH and T3 uptake levels concomitant with hypolipidemia, hyperleptinemia, hyperadiponectinemia, induction of oxidative stress, and reduction of GSH levels.
Keywords: Arsenic; High-fat diet; Lipid profile; Oxidant/antioxidant; Thyroid hormone.