testosterone for pain

[Guest guest]

Testosterone damps pain sensation in males.

15 June 2004 Nature News Service

LAURA NELSON

Men may be keener to fight than women because they feel less pain.

It will come as no surprise to some... men are less sensitive than

women, at least to pain. Researchers have found that the male hormone

testosterone masks feelings of discomfort. They believe that such

tolerance effects may help men to maintain their stamina in fights,

when testosterone levels are high.

" If men are less sensitive to pain, there is more willingness to fight

and participate in further fights, " says a Hau, an animal

physiology and behaviour scientist at Princeton University, New

Jersey,and lead author of the study.

The research team gave testosterone implants to male sparrows and

measured their reaction times to pain. Testosterone allowed the birds

to tolerate discomfort for longer periods, suggesting that the hormone

somehow disguises pain.

They determined the normal pain threshold of male sparrows by dangling

one of their legs in a beaker of hot water and varying the

temperature.

" We measured how long it took for the bird to retract its leg, " says

Hau. The quicker the birds removed their legs, the more pain they were

presumably feeling.

At temperatures below 51 ºC the birds took a long time to respond. But

at higher temperatures they removed their legs quickly, suggesting

that the hot water was hurting them.

The researchers administered testosterone through implants in the

birds' backs. At 52 ºC, treated birds left their legs in the water

for three times as long as untreated birds, indicating that their

tolerance to pain had increased.

The team then tested the effect of a drug that blocks the effect of

testosterone. The birds became more than twice as sensitive to water

at 48 ºC, a temperature at which they normally showed little

discomfort.

Natural painkillers

The researchers think testosterone triggers a chain of events that

leads to an increase in levels of natural painkillers, called

enkephalins.

This may occur in humans too. " I don't doubt that there might be some

effect of testosterone on pain sensitivity in humans, " comments

Fillingim, who works on human pain at the University of Florida in

Gainsville.

Fillingim thinks there could be a case for administering replacement

testosterone to men with chronic pain. These men often take drugs that

lower normal testosterone levels, interfering with the natural

alleviation of their suffering.

References

Hau, M., Dominguez, O. A. & Evrard, H. C. Hormones and Behaviour,

published online, doi:10.1016/j.yhbeh.2004.02.007 (2004). |Article|