[Growth hormone after baclofen in normal and acromegalic subjects]

Serum growth hormone (GH) levels in basal conditions (two samples) and 30, 60, 90, 120, 150 and 180 minutes after oral administration of baclofen (20 mg) were evaluated in 6 healthy subjects and in 6 acromegalic patients. The effect of cimetidine (400 mg i.v.) administrated 45 minutes after baclofen (20 mg by mouth) were evaluated in 9 healthy women. Baclofen was able to significantly rise serum GH levels in normal subjects but no in acromegalic patients. Cimetidine suppress GH increase induced by baclofen. It was concluded that: 1) baclofen, GABAb receptor agonist, stimulate GH secretion by inhibition of GIF secretion or by stimulation of GRF secretion; 2) istamine, through H2 receptors in the hypothalamus, is important to mediate GH release induced by stimulation of GABAb receptors.