Investigating the effects of melatonin on adiposity parameters in rats exposed to cafeteria diet

Introduction and Objective: The prevalence of obesity and related metabolic diseases are rising worldwide. In the last decade, particular attention has been paid to the role of melatonin in regulating glucose and lipid metabolisms. Nevertheless, not all experimental and clinical studies indicate the effectiveness of melatonin in obesity. Thus, further research with more comprehensive methods are required. The aim of this study was to investigate the possible beneficial effects of melatonin on cafeteria-diet induced obesity in rats.Methods: Male adult Wistar rats were treated for ۸ weeks with either standard diet (control, n=۸) or a cafeteria diet in addition to the standard chow (CFD, n=۳۲). After obesity induction, CFD treated rats orally received normal saline (CFD, n=۸) or melatonin at the doses of ۵mg/kg (CFD+Mel۵), ۱۰mg/kg (CFD+Mel۱۰), and۳۰mg/kg (CFD+Mel۳۰) once per day for ۲۸ consecutive days. At the end of the study period, all animals were weighted, euthanized and their blood and tissue samples were collected. Plasma concentrations of glucose, total cholesterol (TC), low density lipoprotein (LDL), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were evaluated. In addition, liver and adipose tissues histopathology was investigated by hematoxylin and eosin staining. One-way ANOVA, and Tukey post hoc tests were used for statistical analysis.Results: Compared to the control group, CFD-treated rats exhibited significant increases in body weight(p=۰.۰۰۵), visceral fat (p<۰.۰۰۱), fasting blood glucose (p=۰.۰۰۲), TC (p<۰.۰۰۱), LDL (p<۰.۰۰۱), AST (p=۰.۰۰۶) and ALT (p=۰.۰۰۲). Liver and adipose tissue histology in CFD-treated rats also revealed hepatic steatosis development and larger adipocytes respectively, when compared to control group. Melatonin treatment at all doses could not reverse obesity, adipocyte hypertrophy, elevated plasma glucose, lipids and liver enzymes. Histological observations of liver showed that melatonin treatment could not ameliorate steatohepatitis in the CFD-treated rats.Conclusion: Taken together, the results of the present study show that melatonin treatment had no significant effect on adiposity related parameters in obesogenic diet-treated rats.

کلیدواژه ها:

Cafeteria diet ، Obesity ، Steatosis ، Melatonin