Growth hormone response to hypoglycemia under gamma-hydroxybutyrate narco-analgesia in the rat

Plasma immuno-reactive growth-hormone (RIA-GH) concentrations were investigated under in vivo continuous blood glucose (BG) monitoring after administration of gamma-hydroxybutyrate (GHB) as well as during spontaneous or insulin-induced hypoglycemia. During the narco-analgesia by GHB a marked secretory episode is consistently observed. This secretion peak is not accurately time related with GHB administration and seems to fade off in aging animals. Strictly controlled hypoglycemia elicits a consistent and specific GH release. In contrast deep hypoglycemic levels resulting in a state of metabolic stress inhibit GH secretion. Our results suggest that previous data on the GH regulation pattern during hypoglycemia may depend upon the anesthetic used and/or nonspecific stress responses following deep hypoglycemia. The above mentioned experimental conditions indicate that GH metabolic regulation is not fundamentally different in rodents and primates.