THE PHEROMONAL RESTORATION OF CYCLIC ACTIVITY IN YOUNG ESTROGENIZED PERSISTENT ESTRUS FEMALE RATS IS A VOMERONASAL EFFECT

Eight sham-operated (SO) and six vomeronasalectomized (VMNX) young adu lt female rats were used to demonstrate the participation of the vomer onasal organ (VNO) in the pheromonal restoration of cyclic activity (P RCA). All rats were normal four-day cycling before and after surgery a nd they received a single Subcutaneous injection of 2 mg of estradiol benzoate (EB) to induce an anovulatory persistent vaginal estrus. Fift een days after EB injection, they were treated by spraying in the nost rils, every 10 min for one hour on only one day, 50 mu L of urine from young fertile males. SO rats showed PRCA in the following days, while VMNX did not. These results support the VNO as the receptor of the ma le urinary pheromone (or pheromones) responsible for PRCA, demonstrati ng that it is possible to improve the function of aging ovaries acting with an exteroceptive stimulus.