Oa. Mora et Mm. Cabrera, PHEROMONAL MALE-INDUCED DIESTRUS AND CYCLICITY IN AGING INTACT AND YOUNG ESTROGENIZED FEMALE RATS, Biology of reproduction, 50(3), 1994, pp. 603-606
Reproductive aging in female rats is characterized by irregular estrou
s cycles, repeated pseudopregnancies, persistent estrus, and a decline
in fertility. The persistently estrous rats do not ovulate or show cy
clic increases of LH despite continued ovarian follicular development.
These rats ovulate after mating with fertile males. On the other hand
, a single injection of estradiol to young female cyclic rats causes p
ersistent anovulatory estrus similar to that of aging rats, which has
suggested that young cyclic estrogen-primed females may be a model for
the study of reproductive senescence. We attempted to determine wheth
er the male factor that elicits ovulation in aging females is pheromon
al in nature. The effect of such a pheromonal factor on the persistent
estrus of young estrogenized females was also tested. We observed the
estrous cycle of aging (7-13-mo-old) and young estrogenized female ra
ts daily. Nasal spraying of urine obtained from young adult male rats
induced diestrus and regular cyclicity in both aging intact and young
estrogenized female rats, probably because of due to pheromones contai
ned in male urine. This fact suggests an important role of chemosensor
y communication in prolongation of the period with normal estrous cycl
es in the female's reproductive life.