Effects of high-fat diet-induced obesity on metabolism and sexual development of juvenile male rats

Objective To explore the effects of high-fat diet-induced obesity on the metabolism and sexual development of juvenile male rats. Methods Three-week-old male rats were divided into the control group and the model group. The two groups were fed normal and high-fat diets, respectively, for four weeks. Modeling was successful if Lee’s index exceeded the upper limit of Lee’s index of the control group. Levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), alanine transaminase (ALT), aspartate transaminase (AST), testosterone (T), estrogen (E2), and insulin-like growth factor 1 (IGF-1) of the rats were monitored. Morphological structures of hepatic and testicular tissues were examined by hematoxylin and eosin (H&E) staining; hepatic steatosis was investigated by Oil Red O staining; and aromatases were detected using the immunohistochemical method. Results Weight, waist-to-height ratio, Lee’s index, weight and thickness of visceral fat, levels of ALT, AST, TC, TG, LDL-C, E2, and IGF-1 of rats were significantly higher in the model group than in the control group ( P  < 0.05). H&E staining revealed that rats in the model group had hepatic steatosis, a disorder of seminiferous tubules, and a reduced quantity of spermatogenic cells. Oil Red O staining revealed a significantly increased accumulation of lipid droplets in hepatic cells. Immunohistochemical analysis revealed that aromatases in hepatic and testicular cells were up-regulated. Conclusion A high-fat diet induces dyslipidemia, thereby causing hepatic steatosis and liver dysfunction, and it significantly influences testicular development, as an increased level of aromatase leads to a reduced T level.