Olfactory bulb removal decreases androgen receptor binding in amygdala and hypothalamus and disrupts masculine sexual behavior.
In these experiments we examined the relationship between olfactory bulb removal, limbic system androgen receptor binding and male copulatory behavior. Sexually experienced male rats were castrated, and implanted with two 10 mm testosterone-filled silastic capsules. Animals then underwent either bilateral olfactory bulb removal (BOB) or sham surgery (Sham). Beginning 1-2 days postoperatively both BOB and Sham operates were given 4 tests for male copulation on alternate days. Less than 40% of BOB males ejaculated. In contrast, 80-100% of sham operates continued to ejaculate throughout the 4 postoperative tests. Cell nuclear androgen receptor binding was assessed in amygdala, hypothalamus, preoptic area and septum 1-2 and 8-9 days after either bulbectomy or sham surgery. We found that olfactory bulbectomy significantly reduces androgen receptor binding in amygdala and hypothalamus. The reduction in androgen receptor binding in amygdala occurs within 1-2 days following olfactory bulb removal and is correlated with the disruption of ejaculatory activity. These data suggest that the neuromodulation by olfactory bulb input to androgen-concentrating neurons in the amygdala and hypothalamus is necessary for effective copulation in male rats.
D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D009830:Olfactory Bulb / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011944:Receptors, Androgen / Q000378:metabolism*; D012726:Sexual Behavior, Animal / Q000502:physiology*
D011944:Receptors, Androgen