EFFECT OF STREPTOZOTOCIN-INDUCED DIABETES ON SOMATOSTATIN RECEPTORS IN THE ANTERIOR-PITUITARY, HYPOTHALAMUS AND CEREBRAL-CORTEX OF THE MALE-RAT

In order to better understand the mechanisms underlying the reduction in GH secretion in diabetic rats, we have characterized and measured S RIH receptors in the hypothalamus and anterior pituitary gland 5 and 9 days after induction of diabetes in the rat. Experimental diabetes wa s induced by an intraperitoneal injection of streptozotocin (STZ) at a dose of 65 mg/kg. Basal plasma GH was significantly reduced in diabet ic rats. Chronic insulin replacement therapy partly restored plasma GH and blood glucose levels in these animals. A significant reduction in SRIH receptor concentrations was demonstrated in the hypothalamus and anterior pituitary gland, 5- and 9- days after STZ injection. These c hanges were not significantly corrected by insulin replacement. Cerebr al cortex SRIH receptor concentrations were unaffected by experimental diabetes. We conclude that hypothalamic and pituitary SRIH receptor l evels are lowered in diabetic rats. These changes may contribute to ab errant GH secretion in diabetes and they indicate that pituitary sensi tivity to exogenous somatostatin should be tested in diabetic patients .