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.
Materials & Methods: 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 oneway
analysis
of
variance
(ANOVA)
followed
by
Tukey’s
test.

Results:

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.
Conclusions: Intracerebroventricular injection of ghrelin suppressed the sexual behavior of male rats
dose-dependently, whereas increased the locomotor activity.