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28.07.2009

Testosterone reduces pain sensitivity

A high testosterone level - and probably a high level of other androgens too - makes your body able to withstand more pain, according to an animal study published in Hormones & Behavior. The research may explain why chemical athletes incur more injuries while taking steroids: the androgens make the body less sensitive to warning pains.

The researchers, working at Princeton University, did experiments with male sparrows. These birds are known to defend their territory aggressively against intruders, and have high testosterone levels. Biologists usually link testosterone to aggression, but the researchers were more interested in the relationship between testosterone and pain. Older studies had already shown that rats that no longer produce testosterone are more sensitive to pain stimuli than rats that are still producing testosterone.

"If you fight you will not only be helped by aggression, but also if you feel less pain", according to the researchers. "We did our experiment to test the theory that testosterone masks the sensation of pain."

And their theory was confirmed, as you can see below. The researchers pumped the sparrows full of testosterone using implants, and then placed the birds' legs in hot water at 51 degrees Celsius. They did the same with sparrows that had not been given extra testosterone. The figure belong shows how long it took for the birds to withdraw their foot from the water.

The figure immediately above shows the results of a similar experiment, only this time the researchers gave the sparrows a cocktail of the anti-androgen ATD (this will be familiar if you use designer supplements) and flutamide. The water temperature was 48 degrees Celsius. The anti-androgens made the birds more sensitive to pain.

Pain researchers believe that the results of the study may also apply to humans. "I don't doubt that there might be some effect of testosterone on pain sensitivity in humans", said Roger Fillingim of the University of Florida in Gainsville in an interview with Nature News. [bioedonline.org June 15, 2004] He thinks that men who suffer from a lot of pain may get relief from testosterone injections, especially if it's because they are taking medicines that lower their testosterone level.

Source:
Horm Behav. 2004 Aug;46(2):165-70.