Effect of a pineal indolamine, 5-methoxyindole-3-acetic acid, on the estrous cycle and reproductive organs of female Wistar albino rats

It has been suggested that the pineal gland has a specific role in the control of cyclic sexual activity in rats. One or more of the compounds isolated from this gland have been considered to be possible anti-fertility agents. In this study, the effect of different doses of 5-methoxyindole-3-acetic acid (5-MIAA) on the estrous cycle and the reproductive organs of female rats was studied. Daily injections of either 100 or 200 micrograms of 5-MIAA significantly prolonged the estrous cycles of mature female rats. After injections of 5-MIAA, an increase in diestrous smears was observed; in addition, the animals had estrous cycles without proestrous phase. Following the injections of 200 micrograms of 5-MIAA, a significant increase in uterine weight, plasma 17 beta-estradiol level and in the number of follicles were observed, and after injections of 5-MIAA (50, 100, 200 micrograms) a medium level of plasma progesterone was obtained. Thus it is concluded that 5-MIAA has an effect on the ovulation process of female rats.