Evaluation of insulin resistance in obese castrated New Zealand white rabbits

Insulin resistance (IR) is observed in obesity and in the type 2 diabetes mellitus in humans. Although rabbits are used as experimental animal models for W. the intravenous insulin tolerance test (IVITT), a specific test for evidencing peripheral insulin sensitivity. is not frequently Used in this species, This Study was Conducted to evaluate insulin resistance ill obese New Zealand white rabbits by IVIIT. A total of 26 rabbits were randomly divided into 3 groups: castrated and obese animals (group CO, n = 7), castrated animals treated with antioxidants (vitamin E and d-limonene, Immunoprotect) (group) Clm, n = 7) and not castrated healthy controls (group NC, n = 12). After weighing and determination of the BMI (body mass index). (he blood glucose concentrations were measured prior to (0 min) and 5, 10, 15, 25, 30 and 45 min after intravenous injection Of human insulin (0.1 U/kg) and the following kinetic parameters were calculated: the index of insulin sensitivity (K-iviti), the glucose disappearance rate (K-glucose), the glucose half-life AUC(glucose) little (t(1/2glucose)), the glucose permanence rate (AUC(glucose)), the minimal glucose concentration (C-min) and its corresponding time (T-min). Whereas the K-glucose and the K-ivitt significantly decreased in castrated and obese rabbits (group CO) compared to healthy controls, (lie other kinetic parameters markedly and significantly increased except for the AUC(glucose) When glucose. castrated rabbits were supplemented with antioxidants (group Clm), the values of the various parameters were closely related to those calculated in controls except for the T-min which has remained significantly more elevated. The BMI negatively correlated with the K-glucose and K-ivitt and positively with the other parameters. These results demonstrate that the insulin resistance evaluating throughout the kinetic analysis of the IVITT ill rabbits occurs during castration-induced obesity and that antioxidant (vitamin E. dlimonene) supplementation may alleviate this deregulation Of glucose metabolism..