Olfactory cues from the female can affect feminine behavior in the male rat

The aim of this work was to study the influence of the hormonal milieu on the facilitory effects of olfactory stimuli originating from female urine on lordosis behavior in orchidectomized (ORCH) feminized rats. Urine from ovariectomized (OVX) rats was shown to increase the proportion of ORCH rats displaying lordosis behavior, an effect which was enhanced if the OVX rats had been given progesterone. Treatment of OVX rats with estradiol benzoate did not affect the pheromonal activity of their urine. Dexamethasone treatment of OVX rats completely suppressed the facilitory effects of their urine on the feminine behavior in males. A higher proportion of feminized rats displayed lordosis following exposure to urine collected from pseudopregnant rats than did their unexposed counterparts. Dexamethasone treatment of pseudopregnant rats did not abolish this effect. These results suggest that the adrenal cortex is capable, in the absence of the ovaries, of manufacturing some pheromonal substance which stimulates feminine behavior in the male rat. The nature of this substance remains unknown. Furthermore progesterone itself is involved in the emission of olfactory signals which control feminine behavior in the male rat.