The Effect of Two Different Intensities of Aerobic Training and Crocin Consumption on Visceral Adipose Cell Size and Insulin Resistance in Ovariectomized Rats Fed With High-Fat Diet

Menopause is associated with a redistribution of adipose tissue towards central adiposity, known to cause insulin resistance. Exercise training and crocin improve blood glucose and insulin resistance, and prevent obesity and type 2 diabetes.  The purpose of this study was to investigate the effect of aerobic training and crocin consumption on visceral fat cell size and insulin resistance in ovariectomized rats fed with high-fat diet. 72 female rats were divided into two groups: ovariectomized (56) and non-ovariectomized (16). Then the rats of these two groups were divided into groups fed with high-fat diet (40% fat) and normal diet. The ovariectomized rats + high-fat diet were divided into 6 groups as follows: 1- control 2- moderate intensity aerobic training 3-  high intensity aerobic training 4- crocin 5- moderate intensity aerobic training + crocin and 6- high intensity aerobic training + crocin. The target groups performed high-intensity aerobic exercise (80-85% VO2max) and moderate aerobic exercise (60-70% VO2max) and received crocin at the rate of 60 mg/kg for 8 weeks. Relative weight of perirenal visceral fat, size of cells and serum levels of glucose, insulin and insulin resistance index (HOMA) were measured. The findings were analyzed by two-way analysis of variance. Moderate intensity training with crocin consumption caused a significant decrease in the relative weight of perirenal fat (p=0.0001). Also, the relative weight of perirenal fat was significantly lower in the high intensity training + crocin group than in the high-fat diet+ ovariectomized group (p≤0.001). The fat cell size in the two training groups (moderate and intense) was significantly lower than the high-fat diet + ovariectomized group (p=0.001), and the difference between the crocin group and the high-fat diet + ovariectomized group was also significant (p=0.03). Fat cell size in exercise groups (moderate and intense) + crocin was also significantly lower than the high-fat diet + ovariectomized group (p≤0.05). High intensity training caused a significant decrease in insulin resistance (p=0.028) and glucose concentration (p=0.041) compared to the ovariectomized + high-fat diet group. Consumption of crocin decreased insulin resistance (p=0.013) and decreased insulin concentration (p=0.008). Also, moderate intensity exercise + crocin caused a significant decrease in glucose (p=0.022), insulin (p=0.011) and insulin resistance (p=0.005) compared to the ovariectomized group + high-fat diet. Consumption of crocin and aerobic training separately and in combination with can reduce visceral fat tissue weight and fat cell size and improve insulin resistance in ovariectomized rats fed with high-fat diet. High-intensity aerobic training seems to be more effective in improving insulin resistance and reducing fat cell size than moderate-intensity training. No additive effects in combination of crocin with exercise training were observed in improvement of insulin resistance or fat cell size.