Biology: Sexual Healing

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More recent research has focused on the hormones dehydroepiandrostone (DHEA) and testosterone, both important for libido. They have been linked to reducing the risk of heart disease as well as protecting the heart muscle after an attack. That may explain why doctors maintain that sex after a heart attack is relatively safe.

--PAIN CONTROL

In the 1970s Dr. Beverly Whipple of Rutgers University identified the female G spot, the vaginal on-switch for female arousal, and stumbled upon one of oxytocin's more potent effects: its ability to dull pain. Whipple showed that gentle pressure on the G spot raised pain thresholds by 40% and that during orgasm women could tolerate up to 110% more pain. But she could not explain the link until the advent of functional magnetic resonance imaging (fMRI). Using fMRI to view the brains of easily orgasmic women as they climaxed, either with visual stimuli or by self-stimulation, Whipple found that the body's pain-killing center in the midbrain is activated during peak arousal. Signals from this part of the brain instruct the body to release endorphins and corticosteroids, which can temporarily numb the raw nerve endings responsible for everything from menstrual cramps to arthritis and migraine for several minutes. Activating this region also reduces anxiety and has a calming effect.

--HE HEALING POWER OF SEX

A trial involving more than 100 college students in 1999 found that the levels of immunoglobulin, a microbe-fighting antibody, in students who engaged in intercourse once or twice a week were 30% higher than in those who were abstinent. Curiously, those who had sex more than twice a week had the same levels as those who were celibate. Could there be an optimal rate of sexual frequency for keeping the body's defenses strong?

Researchers in Sweden are meanwhile exploring how sex affects another immunological function: the healing of wounds. Here again, oxytocin may lead the way. Using injections of oxytocin as a surrogate for arousal, Swedish investigators have found that sores on the backs of lab rats heal twice as fast under the influence of the hormone as without it.

To find out whether the hormone has the same healing effect in people, Ohio State's Glaser and his wife Janice Kiecolt-Glaser, a psychologist at the same institution, are enrolling married couples in an unorthodox study in which each spouse's arm is blistered and then covered with a serum-collecting device. Over a 24-hour observation period, the couples discuss positive aspects of their marriage and mates as well as points of contention, such as finances or in-laws. The Glasers will analyze how levels of oxytocin change during these discussions, along with rates of healing.

--A LONG, HAPPY LIFE?