Differential Effects of Male Stimuli on Follicle-Stimulating Hormone, Luteinizing Hormone, and Prolactin Secretion in Prepubertal Female Mice

Abstract

Puberty may be induced rapidly in young female mice by exposing them to adult males. The relevant male stimuli include a urinary pheromone and tactile cues, the latter acting in a potentiating capacity. The specific action of the urinary pheromone on pituitary gonadotropins was studied. Immature females of a standard size were either paired with adult males, isolated and their bedding sprayed with male urine or maintained as isolated controls. Exposure to male urine resulted in a rapid and significant release of LH [luteinizing hormone] (30 min) which was maintained at an average of 50% higher than levels in isolated controls throughout the 48 h experiment; no immediate changes were observed in either serum FSH [follicle stimulating hormone] or prolactin, but FSH was depressed and prolactin rose progressively during later sampling periods. Cohabitation with an adult male yielded parallel but decidedly stronger responses in the concentrations of all 3 hormones. Exogenous estrogen, administered in a 2nd experiment at a dosage which mimics the puberty-inducing action of a male, suppressed serum FSH and LH while elevating serum prolactin. The male''s urinary stimulus probably exerts its action on immature females via LH release with no immediate and/or direct effects on the other 2 tropic hormones; the delayed alterations in serum FSH and prolactin concentrations accompanying male- and/or urine-exposure are probably secondary consequences of an LH-induced release of estradiol. Attempts to induce the entire pubertal cycle in intact females with subovulating doses of LH, nevertheless, were unsuccessful.