Effect of galanin on basal and stimulated secretion of prolactin, gonadotropins, thyrotropin, adrenocorticotropin and cortisol in humans

Abstract

Galanin enhances both baseline and growth hormone-releasing hormone (GHRH)-induced GH secretion both in animals and in man. Although galanin has a clear influence on the secretion of other anterior pituitary hormones in animals, in man it increases prolactin (PRL) slightly but does not affect spontaneous thyrotropin (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH) or adrenocorticotropin (ACTH) secretion. The aim of our study was to verify the effect of galanin on basal and releasing hormone-stimulated release of gonadotropins, PRL, TSH, ACTH and cortisol secretion. As GH release has been shown to be inhibited by corticotropin-releasing hormone (CRH), we also studied the effect of CRH on galanin-stimulated GH increase. The effect of porcine galanin (15 micrograms/kg iv infused in 60 min) alone and in combination with thyrotropin-releasing hormone (TRH, 200 micrograms iv bolus), CRH (100 micrograms iv bolus) and gonadotropin-releasing hormone (GnRH, 100 micrograms iv bolus) on GH, PRL, TSH, ACTH, cortisol, FSH and LH secretion in seven normal young women (aged 25-30 years) was studied. Galanin infusion caused an increase in serum GH levels (p < 0.02) but failed to modify significantly the spontaneous PRL, LH, FSH, TSH, ACTH and cortisol secretion. The combined administration of TRH, GnRH and CRH caused a significant increase in PRL (p < 0.02), LH (p < 0.02), FSH (p < 0.02), TSH (p < 0.02), ACTH (p < 0.02) and cortisol (p < 0.05), but not in GH levels.(ABSTRACT TRUNCATED AT 250 WORDS)