EFFECTS OF INTRACEREBROVENTRICULAR INJECTION OF GHRELIN ON SEXUAL BEHAVIOR IN MALE RAT

It is well established that ghrelin has effect on gonadotropin and androgen release through its receptors on hypothalamus, pituitary and gonads. The amount of synthesis and release of these hormones directly affect on reproductive behavior in mammals. Therefore, it is expected that ghrelin can affect sexual behavior of mammals. The aim of the present study was to investigate the effects of intracerebroventricular injection of ghrelin on sexual behavior of male rat. Forty male Wistar rats, weighing 200±20 g, were divided into four groups. The animals received saline or 2, 4 or 8 nmol ghrelin through the stereotaxically implanted cannula into the third cerebral ventricle. The sexual behavior indices of male rats were evaluated encountering with female rats 10 min after injection of the ghrelin or saline. As well as the locomotor activity of male rats was investigated by open-field test. Then the experimental data were statistically analyzed by one-way analysis of variance (ANOVA) followed by Tukey’s test. Four and 8 nmol injection of ghrelin caused significant increase in the mount (p<0.05), intromission and ejaculation (p< 0.001) latency compared to the control group. Also the 4 and 8 nmol doses of ghrelin led to a significant increase in the number of mount (p<0.05) and a significant decrease in the number of ejaculation (p<0.001) compared to control animals. No significant changes were observed in the number of intromission after ghrelin injection. Comparison of sexual activity index and copulatory efficiency in the studied groups indicated a significant (p<0.05) decrease in reproductive activity of 4 and 8 nmol ghrelin-received animals compared to the control group. As well we observed a significant increase in locomotor activity of 2 nmol (p<0.01) and 4 and 8 nmol (p<0.001) ghrelin-received animals compared to control group. Intracerebroventricular injection of ghrelin suppressed the sexual behavior of male rats dose-dependently, whereas increased the locomotor activity.