Washington, Apr 3 (IANS): Testosterone, the primary male sex hormone, also keeps depression at bay. Now scientists have figured out how.

Nicole Carrier and Mohamed Kabbaj of the Florida State University have found that a specific pathway in the brain's hippocampus, involved in memory formation and stress response regulation, plays a major role in mediating the testosterone's effects.

Carrier and Kabbaj performed multiple experiments in neutered adult male rats. The rats developed depressive behaviour that was reversed with testosterone replacement, the journal Biological Psychiatry reports.

They also "identified a molecular pathway called MAPK/ERK2 in the hippocampus that plays a major role in mediating the protective effects of testosterone", said Kabbaj, according to a Florida statement.

This suggests that the proper functioning of ERK2 is necessary before the anti-depressant effects of testosterone can occur. It also suggests that this pathway may be a promising target for anti-depressant therapies.

Women are twice as likely to suffer from the blues as men. Men with hypogonadism, when the body produces no or low testosterone, also suffer increased levels of depression and anxiety. Testosterone replacement therapy has been shown to effectively improve mood.