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Teen Aggression and Steroids?




In both sexes, the cause of the teen-age spikes in aggressive and insolent
behavior is the estrogen surge of adolescence. Scientists have found that
most of the effect of testosterone on the brain is paradoxically estrogenic
in nature.

The fact that the human brain is rich in the enzyme aromatase,
resulting in conversion of testosterone into estrogen, explains how the
hormone then acts on the nerve cells of the brain through estrogen
receptors. These specifically hormone linked keys, unleash aggressive
tendencies in the human brain. The female brain also has some receptors for
testosterone, but they are far fewer in number or distribution, and the
converting enzyme aromatase, modifies most of the available testosterone.
Thus, in both boys and girls, as they reach adolescence, their respective
sex hormones surge, but the effects of the hormones on the brain and the
resulting behavior changes, are actually estrogen initiated.

Physicians at Penn State University compared the effects of estrogen
therapy on girls who suffered from delayed onset of puberty, with those of
testosterone on boys who were late in maturing sexually. The girls showed
earlier and larger increases in aggression than did the boys, until the
boys received the final and highest dose of testosterone.

In the Pennsylvania study, the girls may have had a jump on aggressive
behavior over the boys because they were given direct injections of estrogen, and therefore their brains did not need to convert testosterone to estrogen.
The relationship of the brain's estrogen receptors to aggressive behavior
was highlighted by a new study of receptor-deficient mice, presented at the 1999 International Endocrinologists meeting.

Researchers showed that when male mice were genetically deprived of their ability to respond to estrogen, they lost much of their natural aggressiveness, becoming much less likely to fight with other males or to display the general watchfulness exhibited by ordinary male rodents.

When testing the male mice, who were genetically altered, so that they
lacked nearly all estrogen receptors, the researchers discovered that they were unusual in many ways. Normal male mice tend not to wander across open fields as females do, but prefer to sulk along borders; males without estrogen receptors generally took the female route across the fields.

Ordinary males respond to intruders in their territory with violent attacks: chasing, biting and generally seeking to drive off the interlopers. These altered males reacted to newcomers timidly, if at all, perhaps nipping, if the animals came too close, but never actively attacking the strangers. Significantly, the altered males still had their androgen receptors intact. It was only the ability of their brains to respond to estrogen that was defective.

This study is one of several which seem to point at estrogen as the cause
of aggressive behavior in both males and females. DRK
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