Differences in corticosterone binding by regions of the central nervous system in normal and diabetic rats

Cytosol binding of [ 3H]-corticosterone was studied in the anterior pituitary, hypothalamus, hippocampus and cerebral cortex from control and streptozotocin-diabetic male rats after adrenalectomy (ADX). Significant reductions in [ 3H]-corticosterone binding were observed in hypothalamus and hippocampus from ADX diabetics as compared to ADX controls, whereas no differences were obtained with anterior pituitary or cerebral cortex. In contrast to the behaviour of brain tissues, serum binding of [ 3H]-corticosterone was similar in both groups of ADX animals. Scatchard analysis indicated that the reduction in binding in hippocampus and hypothalamus was mostly due to changes in receptor concentration. Other parameters of metabolic function of the tissues, like glycine incorporation into proteins or orotic acid into RNA were similar in brain areas from control and diabetic rats. These findings are consistent with our earlier demonstration of a reduction of corticoid binding in whole brain from diabetic rats. The possibility is discussed that, although diabetes itself may be implicated in this reduction, it may also result from the action of high corticoid levels circulating in diabetics ( Horm. Metab. Res. 9 (1977) 469–473), upon their own brain receptors.