[Effect of sex on the increase of GH induced by galanin, alone or in combination with GHRH with or without pyridostigmine in pubescent subjects].

Growth hormone response to galanin (GAL) and growth hormone releasing hormone have been demonstrated to be higher in females than in males, and moreover the cholinergic system appears to be able to enhance them. On the basis of this presumption, we evaluated the GH response (expressed as area under the curve: AUC-GH) to galanin (GAL, 10 mg/kg i.v.) or GHRH (1 mg/kg i.v.) either alone or associated together and with pyridostigmine (PD, 60 mg p.o.), and to saline infusion as a control, in 5 males and 5 females, in puberty, aged 16 +/- 0.4 years old (mean +/- SD). In females tests were performed during the follicular phase of the menstrual cycle. GAL alone cannot provoke a response from GH unless associated with GHRH. The contemporary administration of PD does not increase the extent of the response. The latter did not differ between sexes. The GHRH-GAL association induced a higher response in GH compared to GAL alone and GAL-PD, without any differences between the sexes. Lastly, the combination GHRH-GAL-PD induced responses that were comparable to GHRH and GAL alone. Therefore GAL does not act alone but enhances the effect of GHRH and the cholinergic system appears to be involved as a modulator. Moreover, the effect of GAL is comparable in both sexes.