Molecular mechanisms responsible for impaired insulin-sensitivity due to obesity are not fully understood in humans or animals. The purpose of this study was to investigate the effects of castration-induced visceral obesity and the influence of antioxidants on blood lipid profile and insulin sensitivity in New Zealand white rabbits.
Twenty-six male rabbits were divided into three groups: castrated-obese and treated with the antioxidant Immunoprotect (CI, n=7), castrated-obese (CO, n=7) and the control group (non-castrated, non-obese, NC, n=12). We assessed glucose and insulin levels and their kinetic parameters, lipid profile, triglycerides (TG), total cholesterol (TC), HDL-cholesterol (HDL-C), body weight (BW), body mass index (BMI), amount of visceral fat (VF) and VF/BW ratio.
All measured markers of obesity (BW, BMI, VF, VF/BW) were significantly higher in both groups of castrated rabbits than in the control group. Apart from HDL-C, the plasma concentrations of all constituents of the lipid profile (TG, TC, HDL-C) were highest in the CO group. There were generally no differences between CI and NC groups for the same traits.
Glucose concentrations and glucose and insulin kinetic parameters were considerably higher (except for glucose elimination rate) in CO rabbits than in NC ones. The CI group showed lower fasting plasma insulin and improved glucose kinetics dynamics than CO rabbits but commensurable values of glucose and insulin kinetics parameters with the NC group.
The results clearly indicate that castration-induced visceral obesity negatively affected the lipid profile and insulin sensitivity and/or responsiveness. Antioxidant supplementation improved blood lipid profile, fatty liver, glucose homeostasis and insulin sensitivity in obese rabbits. In addition, castrated male New Zealand white rabbits might be considered an appropriate animal model to study various metabolic abnormalities related to visceral obesity, such as dyslipidemia and impaired insulin sensitivity.
Source : I.P. Georgiev et al., 2011. Effects of castration-induced visceral obesity and antioxidant treatment on lipid profile and insulin sensitivity in New Zealand white rabbits. Res Vet Sci 90: 196-204. doi: 10.1016/j.rvsc.2010.05.023
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