Sex Difference and Testosterone Modulation: DISCUSSION(6)

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A third alternative is that testosterone, or estradiol formed in the brain via aromatization of testosterone, augmented activity in groups of forebrain neurons that send centrifugal projections to the MOB. For example, noradrenergic neurons in the rat’s locus coeruleus project to the MOB and AOB and contain AR mRNA. The MOB also receives centrifugal inputs from other brain regions including the diagonal band of Broca, the Raphe nuclei, the MA, and the BNST, all of which contain AR as well as ER. Aromatization of androgen occurs in the adult ferret’s MA, BNST, and mPOA. Thus estradiol working via ER could mediate any effects of testosterone in these brain regions. buy ventolin inhalers

Sex Difference in Neuronal Fos Responses to Pheromones

Male and female ferrets showed similar neuronal Fos-IR responses to pheromones in the peripheral regions of the olfactory pathway (i.e., MOB, MA), whereas only females responded in more central regions of this circuit (i.e., BNST, VLH, mPOA). This sex difference is summarized diagrammatically in Figure 7 for gonadectomized, TP-treated ferrets exposed to pheromones derived from estrous females (experiment 1) and from breeding males (experiment 2). The present results corroborate previous studies in which similar sex differences were observed in the regional distribution of neuronal Fos-IR in gonadally intact breeding ferrets both after mating and after exposure to phero-mones from ferrets of the opposite sex. The present experiments involved gonadectomized subjects in which the effects of the same pheromonal stimuli were systematically compared in males and females that had received either oil vehicle or TP Our results show unambiguously that the functional responsiveness of neurons in the central segments of the olfactory pathway (i.e., BNST, mPOA, VLH) is sexually dimorphic, with pheromones derived either from estrous females or breeding males more effectively eliciting neuronal Fos responses in females.