Testosterone has been blamed for everything from the muscular prose of Ernest Hemingway to Wall Street greed to the invention of ice hockey. But the biggest rap against the hormone comes from the biomedical world, which long has maintained a correlation between elevated testosterone levels and a suppressed immune system. After all, males across species die earlier than females and are more prone to stress and disease.
Now a biologist at Washington University in St. Louis is suggesting a completely different role for the hormone that made John Travolta and John Wayne famous. Stanton Braude, Ph.D., a lecturer in biology in Arts and Sciences, analyzed a number of studies that focused on the phenomenon whereby bright or showy male animals advertise their disease resistance. For instance, a male bird, during mating season, will display showy feathers to let females know that he is healthy -- resistant to parasites -- and would be a good mate. This evolutionary trick could be likened to Travolta gliding on the dance floor or the Duke strutting through a saloon to talk to the bar maid. These studies, however, revealed a paradox: testosterone, a long-assumed immunosuppressive, is also known to trigger the sexual display. How, Braude asked, could an immunosuppressive play such a vital role?
"The whole idea that testosterone and stress suppress the immune system makes absolutely no sense evolutionarily," says Braude. "Why would we have evolved to shut off immunity when that's so important to keep us healthy? I began to search for another mechanism for testosterone."
Braude came across a new body of research -- about a dozen studies in all over the past five years -- that questions the whole idea of immunosuppression and suggests that, instead of suppressing the immune system, testosterone and other steroids play a key role in what's called immunoredistribution.
"The redistribution hypothesis predicts that when you are under stress the total
Contact: Tony Fitzpatrick
Washington University in St. Louis