Influence of Streptozotocin-Induced Diabetes on Growth Hormone Secretion in the Rat

The effects of streptozotocin-induced diabetes on pituitary growth hormone (GH) content and release from incubated pituitaries were investigated. Male rats were made diabetic by a single injection of streptozotocin (65 mg/kg) and sacrificed by decapitation 15 days later. Pituitary GH concentration was significantly reduced in streptozotocin diabetic rats as compared to that observed in control animals. The amount of GH released from hemipituitaries was also lower in diabetic rats than in controls. Kinetic characteristics of somatostatin (SRIF) inhibition of GH release were not affected by the treatment. These results suggest that the decrease in plasma GH observed by some investigators in streptozotocin diabetic rats is probably due to a deficiency in GH storage and/or synthesis rather than a change in the responsiveness of pituitary GH cells to SRIF.