You may think it’s love, lust or even passion. Those butterflies you feel in your stomach when you are nervous and that feeling of unquenchable desire that you experience when you want to be intimate, are actually physiologic responses in your body caused by a chemical secreted in the brain called oxytocin.

As scientists have increasingly resorted to using biochemical methods to analyze our love lives, there is now a growing body of evidence suggesting that hormones play a critical role in our emotional responses and relations with others. Hormones play a crucial role in whether two people find each other attractive, and whether they feel connected and are able to bond.

Our craving for sex is part of an inborn reproductive drive that is governed primarily by the hormone testosterone, but oxytocin, generally considered to be a reproductive hormone, also appears to play a significant role in regulating libido as well as orgasm in both men and women.

Scientists at the University of Wisconsin released new research that shows that, in addition to enhancing Nitric Oxide (which dilates blood vessels), the internationally recognized erectile dysfunction drugs Viagra and Levitra also increase production of oxytocin.

Professor Helen Fisher, biological anthropologist at Rutgers University (NY) is convinced that a distinct chemical system involving oxytocin is responsible for our varying love feelings as well as sexual behavior.

She believes that libido in men and women are primarily governed by testosterone. Close emotional bonding, typically occurring during the later phases of a relationship, is regulated in part by oxytocin. From an anthropological standpoint, in primitive man, the enhanced sexual arousal and orgasmic response known now to be created by oxytocin, functioned to increase emotional bonding and connection. Having an orgasm actually helped to cement the relationship, even in primitive days. Having an orgasm increased the chances of continued sexual encounters which then led to the offering of more protection and food and then more sexual encounters.

Uses and roles of Oxytocin

In addition to eliciting feelings of love and sexual arousal, oxytocin has other roles as well in reproduction. Oxytocin has been used for years to induce labor: synthetically manufactured, oxytocin causes uterine contractions in ready-to-deliver pregnant women, which then triggers labor and increases milk let down in young mothers experiencing problems with breastfeeding.

It was quite by accident that it was discovered that oxytocin also directly influences sexual behavior. The hormone was administered as a nasal spray in the course of a study on memory. It was thought that it would improve powers of memory. The results were not quite what the researchers had expected. Instead of outstanding feats of memory, many male subjects reported a “side effect” of increased erections.

During sexual arousal and orgasm oxytocin is released into the blood stream and serum oxytocin levels rise. During sexual stimulation, oxytocin levels steadily rise, and the hormone stimulates the smooth muscles in the genital area and sensitizes the nerves in the genital area and other erogenous zones. As arousal builds, production of oxytocin continues to rise. Oxytocin, in concert  with other neurotransmitters such as acetylcholine and dopamine then causes the nerves in the genitals to fire spontaneously, causing orgasm. Men’s oxytocin levels have been found to quintuple during orgasm, and women’s levels also substantially increase.

Oxytocin is unique among hormones in that its production can be triggered not only by physical contact and stimulation, but also by emotional cues. The glance of a lover, the cry of a baby, or a certain gesture can all generate a flood of oxytocin. Not surprisingly, it’s responsible for a great deal of the bonding that goes on in a relationship. The massive amount of oxytocin released during sex in women is thought to cause women to bond more strongly and let go with greater difficulty once a relationship has progressed to a sexual dimension. That’s not to say that men don’t benefit from oxytocin; far from it. Though their oxytocin levels don’t rise to nearly the stratospheric heights as postpartum women enjoy, levels in men do in fact irise simultaneously with the new mom’s. Similar to a new mother, oxytocin is  responsible for bonding in men and levels significantly rise when they hold and interact with their newborn children .

Oxytocin also plays a role in general health and wellness. Higher oxytocin levels have been associated with reduced stress, healthy sleep patterns, and a general sense of well-being in both women and men. Stress has been proven to increase prolactin levels in women, a hormone that has been linked to breast cancer, brain tumors, and leukemia as well as sexual dysfunction and depression. Oxytocin regulates the body’s production of prolactin and keeps it within the normal range.

Oxytocin and Addiction Treatment

Current research also points to the benefits of oxytocin in the treatment of many kinds of addictions, particularly heroin and cocaine withdrawal. In rats, intravenous self-administration of both heroin and cocaine was significantly decreased when the rats were treated with oxytocin. Oxytocin also regulates appetite through receptors in the brain, inhibiting compulsive eating and preventing obesity.

The human brain is a model of efficiency, and whenever possible it re-uses convenient neural pathways. It makes perfect sense, therefore, that a woman would feel emotions as strong as those associated with “romantic love” toward her baby – Interestingly, the same neurological territory in the brain is activated during sexual intimacy.  This has actually been shown in dynamic MRI brain scans.

With all that said oxytocin is not FDA approved for uses of sexual function. I do, however, prescribe it off-label and have it compounded in the form of a nasal spray for my patients with orgasmic disorder, mood disorder, and/or loss of libido. I am currently conducting a pilot study assessing the affects of oxytocin on arousal and orgasm in menopausal women. (September, 2007)