In 1999, Dr Cho, Dr DeVries, Dr Willias and Dr Carter in the study " The effects of oxytocin and vasopressin on partner preferences in male and female prairie voles" (Behav Neurosci 113:1071-79, 1999) demonstrated that vasopressin is a neuropeptide acting in the brain and able to modify the sexual and social behavior of voles. Interestingly enough, when vasopressin was given to these small rodents they seemed to develop a partner preference. This was interpreted as a monogamous behavior.
Vasopressin Acts in the Brain Through the AVPR Receptor
To act in the brain, vasopressin needs to interact with brain cells through a receptor called AVPR. It turns out that this receptor and vasopressin are also present in human brain cells. In May 2008, Meyer-Lindenberg A. et al. in " Genetic variants in AVPR1A linked to autism redict amygdala activation and personality traits in healthy humans show that the presence of particular forms of the AVPR gene is associated with traits of interpersonal relationships and risks of autism in human patients (Mol Psychiatry, 2008). So what about the role of this molecule and its receptor in humans? Can vasopressin also influence the sexual and social behavior of humans?
A Swedish Group of Scientists Has Linked Vasopressin and Marital Behavior
More recently a Swedish group of scientists in collaboration with American researchers under the supervision of Dr Paul Lichtenstein have attempted to answer these questions in their recent study. This study "Genetic variation in the vasopressin receptor 1a gene (AVPR1A) associates with pair-bonding behavior in humans" (PNAS, Sept 16, 2008, 105, 37, 14153-56) has analyzed a group of more than 2000 volunteers, (initially selected for a different study), through a detailed questionnaire, allowing the scientists to evaluate their quality of marital relationship and assign them a Partner Bonding Score (called PBS).
Men Carrying the 334 Form of Vasopressin Receptor Encountered Marital Crisis
The scientists found that the Partner Bonding Score, or PBS, seemed to be linked to a certain form of the AVPR gene, called 334. Men carrying this form of the gene encountered two times more marital crisis in the last five years, and were twice as likely to be unmarried than men carrying another common form of the AVPR gene. When their spouses were also questioned, the perceived quality of their marital relationship was also associated with the 334 form of the AVPR gene carried by their partner.
Only Men Are Affected by the AVPR 334 Gene
Surprisingly, the marital behavior of women did not seem affected by this form of AVPR gene. Although, there are certainly other genetic and social factors at play.
The Question Remains
The question still remains if the human monogamous behavior is linked to the AVPR gene. This study seems to suggest that the answer is "yes" and some may even imagine using pills or aerosols to control the behavior of their partner.
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