Thyroid morphology and functional alterations in male and female rats with diet-induced visceral obesity

With obesity reaching epidemic proportions worldwide, its impact on thyroid function is gaining increasing attention. Epidemiological studies show an association between obesity, hypothyroidism, and circulating thyroid antibodies but experimental research is needed to investigate the mechanisms underlying these associations. This study aimed to investigate thyroid function indicators in male and female rats subjected to a high-calorie diet for 16 weeks. We assessed mass-metric indices, blood biochemical markers, thyroid morphometry, and tissue concentrations of triglycerides, malonic dialdehyde (MDA), and thyroperoxidase (TPO) activity. The results revealed biochemical features of metabolic syndrome, including elevated thyroxine (T4) levels in peripheral blood. Morphological analysis indicated steatosis and thyroid hypofunction, with increased triglyceride accumulation, decreased TPO activity, and lower MDA levels in the thyroid tissue. These findings suggest that visceral obesity in male and female rats promotes early signs of thyroid dysfunction, potentially leading to hypothyroidism.