It would appear that the erectile dysfunction drug, Viagra, has an effect beyond increasing the blood flow to the penis. A study at the University of Wisconsin has found that the level of oxytocin secreted by the pituitary gland is increased by three times the normal volume when treated with sildenafil (the generic name for Viagra) following neural stimulation. The study was performed on rats, not human beings, but there is no reason at this stage to assume that the reaction would be any different.
Oxytocin is a hormone that is important in social interaction and has been linked to sexual stimulation. This is the first time that Viagra has been linked to a physical effect beyond that of dilating certain blood vessels. Viagra inhibits the production of PDE5 which causes blood vessels to contract, therefore making the penis unable to support an erection viable for penetration in some males. In the same way, PDE5 inhibits the production of oxytocin so when the PDE5 production is inhibited, the volume of oxytocin produced increases. Interestingly, there was no oxytocin produced when the pituitary gland was treated with sildenafil in the absence of neural stimulation.
This research opens the way for further studies into additional uses for this highly popular and successful drug.