ROLE OF GALANIN IN THE REGULATION OF SOMATOTROPE AND GONADOTROPE FUNCTION IN YOUNG OVULATORY WOMEN

The aim of the study was to elucidate the role of the neuropeptide galanin in the regulation of somatotropic and gonadotropic function in normal women. Thirteen normally ovulating (aged 28 to 40 years), non-obese (body mass index, 18.4 to 27.1 kg/m(2)) women with infertility due to a tubal or male factor were studied. Each woman underwent three tests: (1) bolus intravenous (IV) injection of growth hormone (GH)-releasing hormone (GHRH) (1-29)NH2 1 mu g/kg plus gonadotropin-releasing hormone (GnRH) 100 mu g at time 0; (2) IV infusion of porcine galanin 500 mu g in 100 mt saline from -10 minutes; and (3) bolus IV injection of GHRH(1-29)NH2 1 mu g/kg plus GnRH 100 mu g at time 0 plus IV infusion of porcine galanin 500 mu g in 100 mt saline from -10 to +30 minutes. All results are expressed as the mean +/- SEM. GH peak after GHRH was 14 +/- 5 mu g/L; porcine galanin significantly increased serum GH (GH peak, 7.3 +/- 1.2) with respect to baseline levels. No significant differences were observed between either GH peak or GH absolute values after galanin as compared with GHRH alone. Porcine galanin significantly enhanced GH response to GHRH (peak, 31.4 +/- 4.4 mu g/L) with respect to either GHRH or galanin alone. Luteinizing hormone (LH)/follicle-stimulating hormone (FSH) peaks after GnRH were 16.5 +/- 5.3 and 17.4 +/- 4 IU/L, respectively. Porcine galanin did not cause significant increases in serum LH and FSH levels with respect to baseline. Galanin coadministration slightly increased LH (peak, 25 +/- 6.9 IU/L) but not FSH (peak, 17.1 +/- 3.2) maximal responses to GnRH. In conclusion, galanin plays a significant role in the regulation of GH secretion in women, as well as in men. Moreover, this report suggests a minor role of galanin in the regulation of the hypothalamic-pituitary-ovarian axis in women. Copyright (C) 1995 by W.B. Saunders Company