June 17, 2004 ATLANTA -- Researchers at the Yerkes National Primate Research Center of Emory University and Atlanta's Center for Behavioral Neuroscience (CBN) have found transferring a single gene, the vasopressin receptor, into the brain's reward center makes a promiscuous male meadow vole monogamous. This finding, which appears in the June 17 issue of Nature, may help better explain the neurobiology of romantic love as well as disorders of the ability to form social bonds, such as autism. In addition, the finding supports previous research linking social bond formation with drug addiction, also associated with the reward center of the brain.
In their study, Yerkes and CBN post-doctoral fellow Miranda M. Lim, PhD, and Yerkes researcher Larry J. Young, PhD, of the Department of Psychiatry and Behavioral Sciences at Emory University's School of Medicine and the CBN, attempted to determine whether differences in vasopressin receptor levels between prairie and meadow voles could explain their opposite mating behaviors. Previous studies of monogamous male prairie voles, which form lifelong social or pair bonds with a single mate, determined the animals' brains contain high levels of vasopressin receptors in one of the brain's principal reward regions, the ventral pallidum. The comparative species of vole, the promiscuous meadow vole, which frequently mates with multiple partners, lacks vasopressin receptors in the ventral pallidum.
The scientists used a harmless virus to transfer the vasopressin receptor gene from prairie voles into the ventral pallidum of meadow voles, which increased vasopressin receptors in the meadow vole to prairie-like levels. The researchers discovered, just like prairie voles, the formerly promiscuous meadow voles then displayed a strong preference for their current partners rather than new females. Young acknowledges many genes are likely involved in regulating lifelong pair bonds between humans. "Our study, however, provides evidence, in a comparatively simple animal model, that changes in the activity of a single gene profoundly can change a fundamental social behavior of animals within a species."
According to previous research, vasopressin receptors also may play a role in disorders of the ability to form social bonds, such as in autism. "It is intriguing," says Young, "to consider that individual differences in vasopressin receptors in humans might play a role in how differently people form relationships."
And, Lim adds, past research in humans has shown the same neural pathways involved in the formation of romantic relationships are involved in drug addiction. "The brain process of bonding with one's partner may be similar to becoming addicted to drugs: both activate reward circuits in the brain."
The researchers' next step is to determine why there is extensive variability in behaviors among individuals within a species in order to better understand the evolution of social behavior.
The Yerkes National Primate Research Center of Emory University is one of eight National Primate Research Centers funded by the National Institutes of Health. The Yerkes Research Center is a multidisciplinary research institute recognized as a leader in biomedical and behavioral studies with nonhuman primates and rodents. Yerkes scientists are on the forefront of developing vaccines for AIDS and malaria, and treatments for cocaine addiction and Parkinson's disease. Other research programs include social affiliations and behaviors, cognitive development and decline, childhood visual defects, organ transplantation and the behavioral effects of hormone replacement therapy. Leading researchers located worldwide seek to collaborate with Yerkes scientists.
The Center for Behavioral Neuroscience is a National Science Foundation Science and Technology Center consisting of more than 90 neuroscientists at eight metro Atlanta colleges and universities who conduct research on the basic neurobiology of complex social behaviors. Its programs have led to a breakthrough treatment for anxiety-related disorders and new understanding of the potential roles of the neurochemicals vasopressin and oxytocin in autism. CBN's workforce training programs also have contributed significantly to enhancing the diversity of Georgia's burgeoning biotechnology industry.
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