Sex Difference and Testosterone Modulation: DISCUSSION(7)

25 Mar

The volumes of the VNO neuroepithelium and the AOB are significantly greater in male than in female rats. Recently, Herrada and Dulac reported that the distribution across the apical-basal extent of the VNO neuroepithelium of mRNAs encoding putative pheromone receptor proteins is different in male and female rats. Also, the volume of more central segments of the VNO-AOB olfactory pathway, including the BNST and mPOA is significantly greater in males than in females. In the ferret, the volumes of the VNO neuroepithelium and the AOB as well as the MA (unpublished observations) are equivalent in males and females. Obvious morphological sex differences do, however, exist in the ferret’s dorsal POA at its caudal border with the AH. Males, but not females, possess a Nissl-stained cluster of large cells in this region, and many of these large neurons in males express the neuropeptide galanin. Buy Advair Diskus Online

Exposure to pheromones failed, however, to induce neuronal Fos-IR in the dorsal POA/AH of either sex. After males received bilateral excitotoxic lesions centered in this sexually dimorphic dorsal POA/AH region, they showed a female-typical preference to approach and interact sexually with other stimulus males in T-maze tests. The present observation that pheromones augmented neuronal Fos-IR in the mPOA and VLH of female, but not male, ferrets raises the question of whether pheromones play a more central role in females’ expression of heterosexual partner preference.