Different control of GH secretion by gamma-amino- and gamma-hydroxy-butyric acid in 4-year abstinent alcoholics

The present study attempted to establish whether long term abstinence from alcohol restores the stimulatory effects on GH secretion of gamma-aminobuty ric acid (GABA) and gamma-hydroxybutyric acid (GHB) that are absent during the first month of alcohol withdrawal. Six 4-year abstinent alcoholic subje cts - already tested with GHB 4 years earlier, and seven age- and weight-ma tched normal controls, were tested p.o. with 800 mg sodium valproate (a dru g that enhances endogenous GABA activity), 10 mg baclofen (a GABA(B) recept or agonist), 25 mg/kg body-weight GHB, or a placebo. The blood samples for growth hormone (GH) assay were taken every 30 min for the next 150 min. Pla cebo administration did not modify GH secretion in any subject. All drugs i nduced a significant increase in serum GH levels in normal controls. GH sec retion in abstinent alcoholics did not change after baclofen or sodium valp roate administration, whereas the GH response to GHB was similar to that ob served in normal controls. The data confirm previous observations which sug gest that different neuroendocrine mechanisms underlie GABA and GHB control of GH secretion. The data also indicates that the GHB - but not the GABA-s timulated pathway returns to normal in alcoholics after 4 years abstinence. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.