Some Men Lack Receptor for Snuggling, Scientists Say

If your husband doesn’t want to snuggle with you on Valentine’s Day, blame science – a Georgetown researcher says many men have a brain receptor that doesn’t bind well to the “snuggling hormone.”

“Forget about it,” says Thomas Sherman, Ph.D., when asked if some women should keep trying to get their significant others to be romantic. “He is just not wired that way.”

Sherman is a molecular neuroendocrinologist at Georgetown University Medical Center (GUMC).

He says some, but not all men, have a form of vasopressin receptor that makes them less likely to want to wrap their arms around their partner on the sofa, while others have a type that results in them enjoying a snuggle, “nest-building,” child-rearing and the like.

Romance Hormones

Women, Sherman says, have their own “romance hormone” – oxytocin.

But the difference in men’s romantic behavior is simply due to the kind of vasopressin receptor populates his brain.

“The implication is that behaviors associated with ‘love’ – what we think of as a very complicated human emotion,” the scientist explains, “are largely regulated by a pretty simple set of hormones.”

Prairie Versus Meadow

Researchers have looked at how vasopressin and oxytocin are distributed in the brains of male prairie versus meadow voles, Sherman explains.

Sherman says that the male prairie vole mates for life. The vole stays next to his mate after copulating and helps build their nest.

In contrast, the male meadow vole impregnates the female and never sees her again.

The scientist says the variable that matters most between the two types of male voles is how much vasopressin hormone they utilize.

Not surprisingly, he says, studies of brain anatomy show that the meadow voles have the “non-snuggling” receptors that use a lot of vasopressin.

Shocking and Interesting

What followed were some experiments with results Sherman calls “startling.”

Researchers used gene therapy to introduce the “snuggling” vasopressin receptors into the brain of meadow voles, and they started getting closer with their mates and sticking around longer.

“It was shocking, and so interesting,” Sherman says.

Relationship Problems

Scientists then studied male humans, the professor says. Using blood samples, researchers found that men who had the non-snuggling vasopressin receptor had relationship problems.

“These men were likely to be unmarried and if they had a girlfriend, or wife, the women expressed much more dissatisfaction than did women with partners who had different receptors,” Sherman says.

He says Dr. Thomas Insel, director of the National Institute of Mental Health (NIMH), has conducted a lot of this research.

Love Lessons

“The implication for social engineering is pretty amazing,” Sherman says. “You can imagine a scenario where a woman wants to know what kind of vasopressin receptor a partner has, so she can predict what kind of mate he will be for her.”

Sherman uses the example of vasopressin receptor subtypes as a lesson for his students in biochemistry and endocrinology classes.

“I tell them that, yes, we are human, and, yes, we like to think we have free will, but we are animals.”

He offers consoling words to women who may not be romanced on Valentine’s Day.

“The guy probably really loves her, but he doesn’t show it in the ways she might like,” he says. “I would say that, if she wants to, she should think about the other things he does to demonstrate that love.”

(Published February 14, 2012)