Assessment of the impact of high zinc intake on leptin receptor gene expression in wistar rats

In recent years, zinc (Zn) has been extensively employed in agricultural and livestock practices, as well as in baby foods and multivitamin supplements, due to its perceived non-toxic nature and its ability to promote linear growth and body weight in consumers and consequently, its usage is increasing steadily. This study investigates the impact of prolonged excessive zinc intake on the expression levels of the leptin gene in adult Wistar rats without a genetic predisposition to obesity. Three groups of rats were fed basal diets containing 20 mg Zn per kg diet (control group, Group-C), 50 mg Zn per kg diet (Group-T1), and 80 mg Zn per kg diet (Group-T2) for 180 days. Following the dietary treatment, gene expression studies were conducted using adipose tissue from the experimental rats. The findings indicate that dietary zinc supplementation significantly increased leptin receptor gene expression in adipose tissue in a dose- dependent manner. Compared to the control group (Group C), leptin receptor mRNA levels were 3.19-fold (± 0.54) higher in Group T1 receiving 50 mg Zn/kg diet and 4.70-fold (± 0.59) higher in the group receiving 80 mg Zn/kg diet. Our findings indicate that excessive zinc intake can resulted in the upregulation of the leptin gene expression which may lead to leptin resistance and ultimately may contribute to obesity.