High-fat Diet Alone or Combined with Stress Impaired Glucose Tolerance in Female Rats1

Abstract

Background: According to the role of estrogens in metabolic responses to high-fat diet and/or stress, this study aimed to investigate the effect of high- cow intra-abdominal fat diet either alone or combined with acute foot-shock stress on glucose metabolism at proestrus  and diestrus  phases of estrous cycle. Material and Methods: Female rats were divided into high-fat and normal diet groups. The diet groups recruited into control and stressed and finally subdivided into proestrus and diestrus groups. Stress was applied by a communication box. Blood samples were taken after stress exposure to determine glucose related parameters, and then glucose tolerance test was performed. Moreover, homeostasis model assessment of insulin resistance (HOMA-IR) index, body weight, food intake, abdominal fat and adrenal gland weights were evaluated. Results: High-fat diet did not change body weight but decreased food intake and increased energy intake. Moreover, the intra-abdominal fat weight and plasma leptin concentration were increased by applying high-fat diet. In addition, high-fat food consumption caused a decrease in plasma estradiol concentration and an increase in plasma corticosterone level (following stress exposure) in proestrus phase. High-fat diet either alone or combined with stress impaired glucose tolerance at proestrus phase. However, did not affect fasting plasma glucose and insulin levels as well as HOMA-IR index.  Conclusion: The results showed that the high-fat diet used in this study, alone or combined with stress, impaired glucose homeostasis in female rats. However, the proestrus phase compared with diestrus phase was more sensitive to the aforementioned environmental interventions.