LESIONS OF THE ACCESSORY OLFACTORY-BULB DECREASE LORDOTIC RESPONSIVENESS AND REDUCE MATING-INDUCED C-FOS EXPRESSION IN THE ACCESSORY OLFACTORY SYSTEM

The effect of bilateral lesion of the accessory olfactory bulb (AOB) o n the mating-induced enhancement of sexual receptivity was investigate d in ovariectomized (OVX) female rats. Lesions of the AOB significantl y reduced the lordosis-to-mount (L/M) ratio in mating tests conducted 20 to 50 days after the lesion but L/M ratios at earlier (10 days) and later (51-90 days) time periods were not affected. The decrease in L/ M was accompanied by a reduction in the number of c-fos immunopositive cells in the medial amygdala (mAMYG) and bed nucleus of the stria ter minalis (BNST) measured after 3 h of repetitive mating. In the mAMYG, the reduction in c-fos immunoreactivity was correlated to the L/M rati o as well as to the number of intromissions received during the mating tests. The results suggest that information processed from the AOB to the mAMYG and the BNST is important for facilitation of lordosis beha vior, and that the mAMYG may integrate information from the AOB with a scending input activated during copulatory behavior to regulate recept ivity.