Sildenafil's effects may extend beyond sexual organs

Sildenafil citrate (Viagra) may elevate the release of reproductive hormone, according to the authors of an animal study from the University of Wisconsin, Madison. The finding is potentially the first sign of a chemical means by which erectile dysfunction drugs may physically affect the body beyond heightening blood flow to sexual organs.

The drug is thought to raise the level of oxytocin generated by activating the posterior pituitary gland, according to researchers.

"I think this is a missing link in terms of trying to sort out issues around whether there are additional effects of phosphodiesterase type-5 inhibitors," according to study author Meyer Jackson, PhD.

Scientists charted oxytocin released from rat pituitaries following neural stimulation. When treated with sildenafil, the rats released threefold as much oxytocin compared with those who received no drug.

"A big question raised by our study is, will sildenafil do the same thing to nerve terminals that release oxytocin [in the brain]?" Dr. Jackson said. "This is one piece in a puzzle in which many pieces are still not available. But it raises the possibility that erectile dysfunction drugs could be doing more than just affecting erectile dysfunction."

The report was published last month in the online edition of the Journal of Physiology.