| Part I:Chronic intermittent hypoxia and reoxygenation affect glucose tolerance and insulin resistance in non-obese rats[Objective] To explore the effects of chronic intermittent hypoxia and reoxygenation on glucose tolerance and insulin resistance in non-obese rats.[Methods] Sprague-Dawley rats were exposed to intermittent hypoxia environment(PO27-21%) for five weeks, then fasting serum insulin was detected using enzyme linked immunosorbent assay(ELISA), and intraperitoneal glucose tolerance test (IPGTT) was carried out (2g/kg) to evaluate the effects of intermittent hypoxia on glucose tolerance of rats.[Results] Long term intermittent hypoxia significantly decrease the glucose tolerance in rats (17.9±0.7 VS 21.8±1.1 P<0.01), increase insulin resistance index (0.53±0.96 VS 1.16±0.23) (P<0.01), and the impaired glucose tolerance and insulin resistance were improved after a period of reoxygenation(3 weeks or 6 weeks), however,6 weeks of reoxygenation didn't get better results compared with the shorter term reoxygenation[Conclusions] Chronic intermittent hypoxia leads to impaired glucose tolerance and insulin resistance in non-obese rats, and reoxygenation can correct such disorders. Part II:Effect of chronic intermittent hypoxia on adipose tissue hypoxia and adiokines[Objective] Recent studies indicate that Adipose Tissue Hypoxia(ATH) plays a great role in the endocrinal disorders associated with obese, the aim of this study was to explore whether systemic intermittent hypoxia can lead to ATH in otherwise non-obese rats, also the effects of chronic intermittent hypoxia on serum adipokines such as leptin,adiponectin and resistin.[Methods] Sprague-Dawley rats were divided into two groups:Control group and chronic intermittent hypoxia (CIH) group. After exposure to intermittent hypoxia for 5 weeks, Hypoxia inducible factor-1α(HIF-1α) gene and protein in adipose tissue, which will be increased in adipose tissue hypoxia, were detected with real-time PCR and western blot method, serum leptin,adiponectin and resistin were measured using enzyme linked immunosorbent assay(ELISA).[Results] HIF-1αm RNA and HIF-1αprotein were significantly increased in CIH group after exposure to intermittent hypoxia for 5 weeks; serum leptin and resistin were elevated in CIH group (P<0.05), adiponectin was decreased dramatically (24.04±8.48 VS 17.09±4.92, P<0.05).[Conclusion] Chronic intermittent hypoxia leads to adipose tissue hypoxia in non-obese rats; CIH also cause endocrine disorder in adipose tissue with an increase in leptin and resistin and decrease in adiponectin. |
