Effects of intracerebroventricular injection of galanin on hypothalamic- pituitary- gonadal axis in male rat

There is a close relationship between metabolism and hypothalamic- pituitary- gonadal axis (HPG) and most of the peptides or hormones involved in the controlling of metabolism play an important role in regulating reproductive axis activity. Galanin is a peptide which expressed in the hypothalamic nuclei and have been implicated in the control of feeding, cognitive performance, mood and reproduction. In the present study, central injection of galanin was investigated on amount of βLHmRNA expression in pituitary, mean serum LH and testosterone concentrations in rats. Twenty five male Wistar rats in 5 groups(n=5 in each group) received saline, galanin(.63nmol), galanin(1nmol), galantid(1nmol), galanin+galantid via third cerebral injection  at 07:00 - 08:00. Blood samples were collected at 30and 60 min following injections. Four hours after injection the pituitary gland was removed and amount of LHmRNA expression measured by quantitative PCR. Serum LH and testosterone concentrations were measured by using rat kit and the method of the radio-immunoassay(RIA). Galanin injection significantly (p<0.05) increased mean serum LH and testosterone concentrations compared to saline. Co- administration of galanin/galantid did not significantly increase mean serum LH and testosterone concentrations compared to saline or galantid. Galanin increased amount of βLHmRNA expression significantly compared to saline. Co-administration of galanin/galantid did not significantly increase amount of βLHmRNA expression compared to saline or galantid. Galanin play an important role in the hormonal control of hypothalamus- pituitary- gonadal axis.Galanin may control pituitary LH secretion and expression via direct and indirect mechanisms.