The effect of acute ethanol exposure on clonidine-induced growth hormone release in male rats

The influence of acute ethanol (ETOH) on the regulation of GH release has not been clearly elucidated. In this study the effect of ETOH on clonidine (CLON)-induced GH secretion was examined. To test the effect of ETOH on CLON-induced GH release doses of 1, 2, and 3 g/kg ETOH in a 25% ETOH/saline solution or 10 ml/kg saline were injected IP 24 and 1 h before CLON (30 micrograms/kg BW IV). Blood samples were withdrawn through a chronic jugular cannula. ETOH was found to alter the GH surge, which occurred 15 min after CLON administration in controls, in a dose-dependent manner. The 1 g/kg dose reduced the GH surge slightly but not significantly. The 2 g/kg dose suppressed the GH surge which was significantly lower than in controls. The 3 g/kg dose eliminated the GH surge completely. To determine if pituitary GH release is directly influenced by ETOH, animals were injected with GRH (250 ng/kg IV) one hour after the second dose of ETOH (3 g/kg IP). There was no difference in the GH surge in control or ETOH-injected animals. Anti-SRIF administered 30 minutes before ETOH or saline did not alter the response to GRH. These results suggest that ETOH reduces the GH responsiveness to alpha 2-GRH stimulation.