Review: neuroestrogen regulation of socio-sexual behavior of males

Abstract

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 (GnIH), a hypothalamic neuropeptide, inhibits socio-sexual behaviors of male quail by directly activating aromatase and increasing neuroestrogen synthesis in the preoptic area (POA). 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 GnIH 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. 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.

GnIH Control of Feeding and Reproductive Behaviors

“…Importantly, GnIH actions on neuroestrogen synthesis decrease aggressive behavior in birds (28) (Figure 1), providing a new finding that GnIH modifies neurosteroidal milieu in the brain to modulate aggressive behavior [see Ref. (146) for review]. Future studies are needed to develop the emerging concept of GnIH and other hypothalamic neuropeptides modifying the neurosteroidal milieu in the brain and the impact of its function.…”

Contribution of GnIH Research to the Progress of Reproductive Neuroendocrinology

“…Based on these findings, it now appears that GnIH not only acts on the pituitary but in the brain to affect a number of behaviors, including reproductive behavior through changes in neurosteroid, such as neuroestrogen, biosynthesis in the brain [( 32 ), for a review, see Ref. ( 33 )]. Thus, the following 15 years of GnIH research in collaboration with world’s leading laboratories have permitted a more complete understanding of the neuroendocrine control of reproductive behavior and physiology [for reviews, see Ref.…”

“…GnIH may inhibit aggressive behavior by directly activating aromatase and increasing neuroestrogen synthesis in the brain beyond its optimum concentration for the expression of aggressive behavior. Partially adapted from Ubuka and Tsutsui ( 33 ).…”

Developmental trajectories of aggressive behavior in children from ages 8 to 10: The role of sex and hormones

“…Nevertheless, it is important to point out that although some of these studies found a positive relationship between estradiol and aggression in male subjects (Finkelstein et al, ; Gladue, ), others only observed this positive association in women (Hood, ; Inoff‐Germain et al, ). In a recent review on neuroestrogen regulation of the socio‐sexual behavior of males, Ubuka and Tsutsui () concluded, based on evidence obtained from various different species, that while a basal concentration of estrogens is necessary for maintaining the socio‐sexual behavior of males (including aggression), higher concentrations of these hormones may in fact inhibit aggressive behavior. Indeed, several studies have found that estrogen therapy in patients with dementia has an anti‐aggressive effect (Kyomen et al, ; Orengo et al, ).…”