Obestatin induces testosterone secretion from rat testis in vitro

Abstract

In this study, the effect of obestatin (23 amino acid peptide) on testosterone secretion in vitro, in the rat testis was observed. For this purpose, two different doses of obestatin (10^-9 M and 10^-8 M) were used alone and in combination with human chorionic gonadotropin (hCG) in fasting and fed conditions in two age groups. Fasting induced a significant reduction in body weight (p < 0.05) and plasma testosterone concentrations (0.001). hCG stimulated testosterone secretions were significantly (p < 0.05) high as compared to the basal control testosterone concentrations after 90 min in some groups and 180 min of incubation in all groups. Obestatin at the dose of 10^-9 M alone and in combination with hCG failed to change testosterone concentrations in all groups; however, 10^-8 M obestatin significantly (p < 0.05) induced hCG stimulated testosterone concentrations in both normally fed pre-pubertal and adult rats. No significant difference was noticed in 48 h fasted groups. This data suggests that, obestatin is a positive modulator of testosterone secretion and its effect depends upon the nutritional status of the body.

Key words: Obestatin, testosterone, rats, in vitro.