Blockade of mu-receptors in striatum subregions differentially regulates monogamous pair bonding in prairie voles

Social neuroscience is a very important area of cognitive neuroscience that deals with fundamental questions such as how social bonding and group formation take place. Pair bonding, i.e., formation of lasting monogamous relationships, is a specific form of social bonding that is observed in humans and also in some other species such as prairie voles.  Neurochemistry, including the opioidergic system, is known to play a pivotal role in pair bonding. Previous animal studies have demonstrated that striatal mu opioidergic receptors regulate pair bonding, however, the relative contributions of striatal subregions have remained unexplored.

In their recent study, Dr. Shanna Resendez et al. (2013) blocked the mu-receptors in different areas of the striatum of female prairie voles during cohabitation with male prairie voles under settings that have been previously observed to result in pair bonding, measured as partner preference following the cohabitation period. Indeed, antagonizing the mu-receptors with one or three microgram doses of H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH₂ produced differential effects, with decreases in mating behaviors during the cohabitation period as well as inhibition of subsequently observed partner preference observed with blockade of mu-receptors in dorsal striatum. Blockade of dorsomedial nucleus accumbens shell mu-receptors, in turn, inhibited acquisition of partner preference without reducing mating behavior during the cohabitation period. As an important control measure, mu-receptor blockade did not result in reduced locomotor activity.

These results significantly advance understanding of the role of mu-opioidergic receptors in pair bonding. In the light of these results, the blockade of mu-opioid receptors in dorsal striatum appears to reduce acquisition of partner preference by inhibiting mating behavior. In contrast, antagonizing the mu-receptors in the dorsomedial shell of nucleus accumbens reduces pair bonding by reducing the hedonic and/or rewarding aspects of mating behavior. Overall, this study very nicely demonstrates the power of behavioral-pharmacology paradigms in carefully selected animal models in unraveling the neural basis of higher-order social behaviors such as monogamous pair bonding.

Reference: Resendez SL, Dome M, Gormley G, Franco D, Nevárez N, Hamid AA, Aragona BJ. Mu-opioid receptors within subregions of the striatum mediate pair bond formation through parallel tet distinct reward mechanisms. Journal of Neuroscience (2013) 33: 9140–9149. http://dx.doi.org/10.1523/JNEUROSCI.4123-12.2013