"It's not you, it's me." This dreaded phrase is often heard during breakups, but rarely believed. However, neuroscientists are conducting research in prairie voles that suggest the ex may have been telling the truth all along. In guys, a neuropeptide (something that sends signals to your brain to control your behaviour) called vasopressin brings about behaviour associated with long term relationships. Vasopressin also happens to regulate blood pressure and controls how often you go to the washroom. Vasopressin binds to its receptor in the brain, which is encoded by the gene AVPR1A.

Did You Know?
With insects like Drosophila (fruit fly) geneticists tend to give their genes more comical names, such as frizzled, cheap date, brainiac, and swiss cheese. Geneticists studying mammals on the other hand, are usually less creative.

There are multiple variants, or mutational types, of AVPR1A that determine how much vasopressin receptor is expressed. Scientists found that men with variants of AVPR1A that result in lower receptor expression are usually less happy in a monogamous relationship, less likely to remain married, and more likely to report a recent crisis in their marriage. Let's just hope all this information doesn't give cheating boyfriends a new excuse: "It's not my fault! It's my AVPR1A gene!"

Did You Know?
Prairie voles mate for life, but for some reason their close cousins, the meadow voles, are polygamous. Scientists have narrowed down the region of AVPR1A that is unusually prone to expanding or shrinking, which allows variants of the gene to arise within relatively short evolutionary time scales.

In girls, the neuropeptide responsible for mediating the bond with their partner is oxytocin. Oxytocin is in the same hormone family as vasopressin, is released during child birth, delivery and breast feeding, and helps form that unbreakable mother-child bond that is universal among mammals. It seems the hormone that makes a woman attached to her child is the same one that makes her attached to her mate. Looks like clingy girlfriends also have a new excuse: "It's my oxytocin receptor!"

With these hormones in mind, many have begun to flirt with the idea of "love potions." Can't get the guy with a wandering eye to commit? Perhaps you can slip some vasopressin into his smoothie. Guys should throw out their Axe bodyspray and go for some "eau de oxytocin" instead. Want that creep out of your face? Give him/her a vasopressin or oxytocin receptor antagonist.

Did You Know?
The receptors for vasopressin and oxytocin are called G protein-coupled receptors, which are major targets for drug companies. Molecules that bind to these types of receptors and activate them are called agonists, while molecules that inactivate them are called antagonists.

Since using these hormones to make someone fall in love with you is a bit unethical, it is probably a good thing that there are some challenges to formulating an edible love potion. Vasopressin and oxytocin are peptides, which are essentially smaller versions of the proteins found in beef, chicken, etc. Therefore, if you were to eat these hormones, your digestive system would just break it down to amino acids. Plus, there is the challenge of getting these hormones to cross the blood brain barrier to access their receptors in the brain. However, vasopressin-based therapies are still attractive to the biomedical research community. One potential application is in people with autism, a neurodevelopmental disorder characterized by pervasive social deficits, where we can take advantage of oxytocin and vasopressin's ability to develop social connections.

There still many kinks to work out before a love potion can be made available to the masses. It looks like Facebook relationship statuses such as "It's Complicated" and "In an Open Relationship" are here to stay...at least for now...

Read more about it!

Larry J. Young. "Being Human: Love: Neuroscience Reveals All." Nature 457, 148 (8 January 2009).

Elizabeth A.D. Hammock. "Gene Regulation as a Modulator of Social Preference in Voles." Advances in Genetics 59, pages 107-127 (2007).

Elizabeth A.D. Hammock and Larry J. Young. "Oxytocin, vasopressin and pair bonding: implications for autism." Philosophical Transactions of The Royal Society B 361, 471, pages 2187-2198 (2006).

Joanne Hsieh is a Ph.D. candidate in the Department of Biochemistry at the University of Toronto. Her research is on matters of the heart (actually, it’s the link between diabetes and cardiovascular disease). She’s been going out with her boyfriend for the past 3 years and thought the research for this article would help her move the relationship along.



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