Couples in long-term relationships who want to strengthen their bond should look no further than the love hormone itself: oxytocin. Men could be more inclined to stay monogamous, and deem their partner more attractive during the release of oxytocin, which stimulates the reward center in the brain, according to a recent study.  

Oxytocin, also released after childbirth and during nursing for women, is only produced during interactions with the closest people of a person’s social circle. The powerful hormone is typically released by the pituitary gland, and acts as a neurotransmitter in the brain produced in nerve cells rather than glandular cells like most hormones, according to Psych Central. Romantic gestures, such as cuddling, hugging, or kissing could boost oxytocin levels in the body, which help enhance social bonding between individuals.

In male-female bonds, the love hormone plays an important part in the human sexual response cycle. It changes the brain signals related to social recognition via facial expression — possibly by activity in the amygdala — the part of the brain that plays a primary role processing important emotional stimuli. Viewing photos of a loved one, especially a romantic partner, causes an increase in oxytocin levels, which produces an emotional response increasing attraction and the chances of staying monogamous.

A team of researchers at the University of Bonn, in Germany, investigated the effects oxytocin had on the level of attraction between loving couples and their ability to remain faithful. Twenty heterosexual men who were in long-term relationships for 28 months, on average, were part of the sample size in the study.

First the researchers showed the participants pictures of either their female partners, a woman they had never met, female colleagues of many years, or a house. The photos of the women were matched so that one woman wasn’t more "attractive" than the other.

All of the men in the study were either dosed with oxytocin via nasal spray, or were given a placebo spray before they rated their levels of attraction to their partners and the other women. Brain activity was also evaluated through the use of magnetic resonance tomography.

The findings of the experiment revealed that men who took oxytocin were more likely to rate their partners as more attractive and sexually arousing than the other women. With regards to brain activity, two areas of the brain responsible for feeling reward and pleasure were highly stimulated when the men saw pictures of their partner. Conversely, the participants expressed suppressed feelings of reward and pleasure when they saw photos of other women despite being measured by the researchers as equally attractive.

"When the men received oxytocin instead of the placebo, their reward system in the brain when viewing the partner was very active, and they perceived them as more attractive than the other women", said Dirk Scheele, lead author of the study in a press release.

This suggests simple familiarity does not suffice to stimulate a bonding effect in male-female relationships. The researchers are convinced oxytocin activates the reward system in a male-female dynamic of loving couples implying that the love hormone has a selective effect. This effect released during intimate physical contact therefore boosts their likeliness of being monogamous, as it makes a woman more attractive in a man’s eyes.

"When oxytocin strengthens the partner bond, it increases the stability of the persons providing nutrition, and thus the chances of survival for the progeny", wrote Prof. Dr. René Hurlemann, executive senior physician at the Inpatient and Outpatient Department of Psychiatry and Psychotherapy of the Bonn University Medical Center, Medical Xpress reports. Overall, oxytocin is found to contribute to romantic bonds in men by enhancing their partner’s beauty and value when compared with other women, highlighting the effects of the love hormone.

In a similar study published, researchers found that men in committed relationships chose to keep a distance between themselves and an unknown woman that they found attractive due to oxytocin. The participants were administered with oxytocin or placebo via a nasal spray before they were introduced to an attractive female experimenter who moved toward and away from the volunteers. The men in serious relationships were more inclined to keep a distance 10 to 15 cm between themselves and the woman when compared to those who were single. The researchers concluded that oxytocin plays an important role in social bonding and monogamy for committed men.

To learn how to naturally boost oxytocin levels in your relationship, click here.

Source: Becker B, Gunturkun O, Hurlemann R et al. Oxytocin enhances brain reward system responses in men viewing the face of their female partner. Proceedings of the National Academy of Sciences. 2013.