Estrogen/Estradiol & Masculinity

[Ron J]

Some members theorized masculinizing effects from estrogen/estradiol. I've read that it causes cell division, liver enlargement and brain enlargement(?). But many members claim that it's bad for bone formation, so how does it masculinize? Is the induced cell division only/mostly cancerous or growth in general? How do androgens compare in regards to cell division/growth(tissues and bone(aside from muscle mass))?

 

[schultz]

I'm not sure about its action on hair growth or any of that stuff, but as far as the brain goes it is well established that estrogen is important for male behaviour. I am under the impression though that it is the local conversion of testosterone to estrogen that has this effect. Here is a quote from this study...

"Estrogen is also essential for male behaviors. The requirement for estrogen to masculinize behavior seems counter-intuitive as this ovarian hormone is essentially undetectable in the male circulation. All estrogenic steroids are synthesized in vivo from testosterone or related androgens in a reaction catalyzed by aromatase. Aromatase expressing cells in the brain convert circulating testosterone into estrogen, and it is this local estrogen that is thought to control dimorphic behaviors in males (Figure 1A) (MacLusky and Naftolin, 1981; Naftolin and Ryan, 1975). Consistent with a requirement for estrogen in male behaviors, aromatase activity is essential for male behaviors. Mice mutant for aromatase exhibit a profound reduction in male sexual behavior and aggression (Honda et al., 1998; Toda et al., 2001). Similar to testosterone, estrogen is essential in neonates and adults for the display of dimorphic behaviors in males (Finney and Erpino, 1976; McCarthy, 2008; Scordalakes and Rissman, 2004; Toda et al., 2001; Wallis and Luttge, 1975)."

 

[Ron J]

Thanks for the link schultz. Anything on physical changes aside from the conventional effects of estrogen, like weight gain in certain areas and behavior?

 

[Dante]

I'm not sure about its action on hair growth or any of that stuff, but as far as the brain goes it is well established that estrogen is important for male behaviour. I am under the impression though that it is the local conversion of testosterone to estrogen that has this effect. Here is a quote from this study...

"Estrogen is also essential for male behaviors. The requirement for estrogen to masculinize behavior seems counter-intuitive as this ovarian hormone is essentially undetectable in the male circulation. All estrogenic steroids are synthesized in vivo from testosterone or related androgens in a reaction catalyzed by aromatase. Aromatase expressing cells in the brain convert circulating testosterone into estrogen, and it is this local estrogen that is thought to control dimorphic behaviors in males (Figure 1A) (MacLusky and Naftolin, 1981; Naftolin and Ryan, 1975). Consistent with a requirement for estrogen in male behaviors, aromatase activity is essential for male behaviors. Mice mutant for aromatase exhibit a profound reduction in male sexual behavior and aggression (Honda et al., 1998; Toda et al., 2001). Similar to testosterone, estrogen is essential in neonates and adults for the display of dimorphic behaviors in males (Finney and Erpino, 1976; McCarthy, 2008; Scordalakes and Rissman, 2004; Toda et al., 2001; Wallis and Luttge, 1975)."

The thing is this varies according to species. DHT+E2 both are required for male rats but only DHT was required for rhesus macaques as i read in an endo book. I can't recall the name of that book but examples were given for a lot of different species. There has been no such open primate study( chimps, humans, gorillas) and i doubt there ever will be due to animal rights issue . As far receptor reactivity goes, DHT metabolites like 5-beta diol has more preference for ER-beta than estradiol itself as rats given exogenous 5-beta diol show calm, composed , anxiolytic behavior as opposed to estradiol which exhibit aggression . So , it also depends on the kind of compound that reacts with the estrogen receptor.