In vivo role of corticosterone in regulation of insulin receptors in rat adipocytes during hypokinesia

Abstract

The role of corticosterone in the changes of insulin receptors of rat adipocytes during hypokinesia was investigated. Three groups of adult male Wistar rats (1. intact; 2. adrenalectomized; 3. dexamethasone treated) were exposed to hypokinesia for various period. The plasma levels of corticosterone, insulin and glucose and the binding of insulin (125I-TyrA-14 monoiodoinsulin) to isolated adipocytes were determined. A significant increase of plasma corticosterone level and a decrease of insulin binding to adipocytes were found in rats exposed to hypokinesia for one day. After 3 and 5 days of hypokinesia the corticosterone level in plasma was decreased to the concentration observed in the control animals. Also the binding of insulin to adipocytes returned to the values found in control group. In adrenalectomized rats exposed to hypokinesia no changes of insulin receptors in adipocytes were noted. The treatment of rats with dexamethasone (both, the intact and adrenalectomize ones) resulted in a decrease of insulin binding in fat cells. These results showed that an increase of corticosterone in plasma after the short term exposure to hypokinesia or the injection of dexamethasone to intact or adrenalectomized animals are followed by the decrease of insulin receptors in adipocytes suggesting that glucocorticoids participate in the regulation of insulin receptors in adipocytes during short term hypokinesia.