By Maureen Salamon
Oxytocin’s ability to foster calm and secure feelings is apparently a perfect start to a satisfying roll in the hay.
The hormone’s role in sexual arousal has been the subject of research for at least the last quarter-century. A 1987 study in the Journal of Clinical Endocrinology and Metabolism used a novel set-up to measure blood plasma levels of oxytocin before, during and after sexual stimulation in both men and women.
With intravenous catheters providing a continuous sample of blood, nine men and 13 women were also rigged with devices that measured blood flow and muscle activity in their lower pelvis during self-stimulation to orgasm. The research showed that blood plasma levels rose during arousal in both genders and were significantly higher during orgasm than during prior baseline testing.
This finding has been supported by others. According to The Institute for Sexual Medicine, several studies have indicated that blood plasma levels of oxytocin increase at orgasm and stay significantly higher than baseline even five minutes after self-arousal ends.
Another study reported oxytocin levels jump in women during stimulation of their nipples, genital area and genital tract, according to the institute, which noted that the hormone’s influence on muscle contractions may facilitate sperm and egg movement toward fertilization.
And a cocktail of brain chemicals that includes oxytocin is released in men during ejaculation, according to Scienceline, a project of New York University’s Science, Health and Environmental Reporting Program. These chemicals can intensify bonding between sexual partners.
As with much research, animals have also been the subject of studies on oxytocin’s sexual effects. In a 2001 study in the journal Physiological Review, spontaneous erections in rats was reported after oxytocin was injected into their cerebrospinal fluid.
Some researchers, however, feel the jury is still out on oxytocin’s impact on sex.
“The human literature is a little scant,” says Dr. Kai MacDonald, an adjunct professor of psychiatry at University of California-San Diego. “I know of no studies giving people oxytocin and they get more randy. They’ve shot it up the nose of hundreds of people, and I don’t think most of them got raging erections or longed for their partner more.”
But MacDonald acknowledges that research has provided “some tantalizing tidbits” of information that may someday lead to oxytocin-based therapies for sexual disorders.