Hormonal Pattern of the Pheromonal Restoration of Cyclic Activity in Aging Irregularly Cycling and Persistent-Estrus Female Rats1

Abstract

This study reports the hormonal pattern of pheromonal restoration of cyclic activity (PRCA) in irregularly cycling (IC) and in anovulatory persistent-estrus (PE) aging female middle-aged Wistar rats. Hypothalamic content of LHRH and plasma levels of LH, FSH, estradiol (E2), and progesterone (P) were measured by RIA methods, and prolactin (PRL) was examined by ELISA in 1) normal four-day cycling rats, 2) saline-treated IC and PE rats, and 3) IC and PE rats treated with sprays of male urine (50 microliters every 10 min for 1 h on only one day, at a distance of 1 cm from the nostrils). Group 1 showed low levels of LHRH and high levels of LH, FSH, E2, P, and PRL in the afternoon of proestrus (PR). In group 2, the pattern was not cyclical and the levels of the hormones were higher than basal for the cyclic rats, except for P, which was lower. Group 3 showed a depletion of the hypothalamic LHRH and an increase in plasma LH, FSH, E2, Pm, and PRL. FSH, E2, and P showed the strongest rise, leading to an elevated ratio of FSH to LH. Four-day estrous cycles reappeared in urine-treated rats on the succeeding days. The cyclic behavior of the PRCA hormones was, qualitatively, the same as in the normally cycling rats. According to the results, the origin of the PRCA effect is an olfactory input to the hypophysiotropic area of the hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)