It has been shown that E2 can increase c AMP in the uterus of ovariectomized mice within 15 s (Szego and Davis, 1967) suggesting non-genomic actions of E2. Functional analysis of neurosteroidal oestrogen using gene-disrupted and transgenic mice.
It is thought that estrogen (neuroestrogen) synthesized by the action of aromatase in the brain from testosterone activates male socio-sexual behaviors, such as aggression and sexual behavior in birds.
We recently found that gonadotropin-inhibitory hormone (Gn IH), a hypothalamic neuropeptide, inhibits socio-sexual behaviors of male quail by directly activating aromatase and increasing neuroestrogen synthesis in the preoptic area (POA). doi: 10.1006/bbrc.1998.9672 Pubmed Abstract | Pubmed Full Text | Cross Ref Full Text | Google Scholar Huffman, L.
The POA is thought to be the most critical site of aromatization and neuroestrogen action for the regulation of socio-sexual behavior of male birds.
We concluded that Gn IH inhibits socio-sexual behaviors of male quail by increasing neuroestrogen concentration beyond its optimal concentration in the brain for expression of socio-sexual behavior.
On the other hand, it has been reported that dopamine and glutamate, which stimulate male socio-sexual behavior in birds and mammals, inhibit the activity of aromatase in the POA.
Multiple studies also report that the activity of aromatase or neuroestrogen is negatively correlated with changes in male socio-sexual behavior in fish, birds, and mammals including humans. doi: 10.1038/35036326 Pubmed Abstract | Pubmed Full Text | Cross Ref Full Text | Google Scholar Honda, S., Harada, N., Ito, S., Takagi, Y., and Maeda, S. Disruption of sexual behavior in male aromatase-deficient mice lacking exons 1 and 2 of the cyp19 gene.
Here, we review previous studies that investigated the role of neuroestrogen in the regulation of male socio-sexual behavior and reconsider the hypothesis that neuroestrogen activates male socio-sexual behavior in vertebrates.
It is considered that basal concentration of neuroestrogen is required for the maintenance of male socio-sexual behavior but higher concentration of neuroestrogen may inhibit male socio-sexual behavior. doi: 10.1016/0018-506X(83)90021-1 Pubmed Abstract | Pubmed Full Text | Cross Ref Full Text | Google Scholar Hinuma, S., Shintani, Y., Fukusumi, S., Iijima, N., Matsumoto, Y., Hosoya, M., et al. New neuropeptides containing carboxy-terminal RFamide and their receptor in mammals.
Originally it was considered that males display male-typical behavior because they are exposed to androgen secreted by the testis, whereas females display female-typical behavior because they are exposed to female sex hormones secreted by the ovary, such as 17β-estradiol (E2) and progesterone (Reviewed in Beach, 1948; Balthazart et al., 2004).
However, it was later discovered that estrogen is able to activate male-typical behavior in castrated male rats (Beach, 1942). Hormonal specificity and activation of sexual behavior in male zebra finches.
As the male-typical behavior activated by androgen can be blocked by concomitant antiestrogen treatment (Beyer and Vidal, 1971) and because the anterior hypothalamus can synthesize estrogens (neuroestrogen) from androgens by aromatization (Naftolin et al., 1972, 1975), it was hypothesized that central actions of androgen in males require its aromatization into neuroestrogen in the brain (aromatization hypothesis; Yahr, 1979).