Combination of Galanin and Growth Hormone Releasing Hormone （GHRH） Enhances GH Release

Galanin is a new hypothalamic hormone which induces GH release. It is well known that in normal subjects repeated administralion of GHRH leads to decrease GH response. We studied the effects of two consecutive GHRH boluses (1.0ug/kg, iv, every 120min) alone or coadminitstered with galanin (15ug/kg, infusion, over 60 min) at the second bolus injection on GH release in 6 healthy volunteers. It was found that the GH release after the second bolus of GHRH alone was significantly lower than that of the first one. whereas, Galanin remarkedly enhanced the GH response to the second GHRH bolus. This result showed that combination of galanin and GHRH reinstated the GH response to the repeated GHRH stimulation in man. The mechanism of this effect might be via an inhibition of somatostatin secretion in hypothalamus.