The effect of short-term starvation on interaction of hypothalamus-pituitary-gonads and growth hormone axes in adult male rats.

Starvation changes the pituitary hormones serum levels, especially gonadotropins and growth hormone (GH). There are controversies about the effects of starvation on the hormonal changes of the two axes. Therefore, this study was carried out to show the interaction of hypothalamus-pituitary-gonad (HPG) and GH axes during fasting. In this experimental study, thirty-two adult male rats were divided into four equal groups. The starvation group was deprived of food for 4 days with free access to water and received injection of the vehicle (corn oil, 1ml/day). The control group had free access to water and standard laboratory animal food and received injection of the vehicle (corn oil, 1ml/day). Starvation + testosterone (St+T) group were deprived of food for 4 days with free access to water and received injection of testosterone (1 mg/kg/day). Starvation + estradiol (St+E) group was deprived of food for 4 days with free access to water and received injection of estradiol (1 mg/kg /day). Then the levels of FSH, LH, GH, estradiol and testosterone were measured. Data were analyzed using ANOVA and Toki tests. During the fasting, the level of serum GH increased to 64% but the level of FSH, LH and testosterone decreased by 33%, 31% and 41%, respectively (p<0.001). No significant change was found in serum level of estradiol. The increase of serum GH levels in St+T and St+E groups were less than that of the starvation group (p<0.001). Also in St+T and St+E groups the decrease of FSH and LH were more than those in the starvation group (p<0.001). Based on the results of this study, the two axes showed the same mechanism in response to short-term starvation