A New Breadth to Estrogen's Bisexuality

Article excerpt

Most people have been taught to think of estrogens as female sex hormones and androgens as male sex hormones. "But that's simply not true," notes Donald W. Pfaff.

Indeed, a pair of studies by Pfaff, a neurobiologist at Rockefeller University in New York, and his colleagues has unveiled estrogen's previously unrecognized depth and breadth in establishing gender-specific behaviors in both males and females.

Estrogen and other hormones operate by binding to receptors on or in cells and triggering the production of one or more chemical products. Pfaff's team worked with mutant mice born without the normal receptors for estrogen. These males, which don't respond to estrogen, had trouble mating in adulthood. Their reproductive organs "looked all right," Pfaff notes. Moreover, the animals tried to mate, he says, "so their motivation was not affected." What had been compromised was their ability to penetrate the female and release sperm, suggesting that their problems trace to some neurobiological defect, Pfaff says.

This wasn't their only behavioral peculiarity, observes coauthor Sonoko Ogawa, a behavioral neuroscientist at Rockefeller. The mutant males proved far less aggressive and exhibited less stereotypical masculine social behavior than their male littermates, which responded normally to the presence of estrogen. The team reports its findings in the Feb. 18 Proceedings of the National Academy of Sciences.

In the December 1996 Neuroendocrinology, the same team reported a suite of comparably atypical behaviors in female mice possessing the same genetic inability to respond to estrogen. …