Monogamy: dopamine ties the knot

Prairie voles form lasting pair bonds with their mating partners after a single experience of sexual activity, and this reward-related learning depends on dopamine. A new paper reports that two dopamine receptor subtypes contribute differently to the initial formation of pair bonds and to their maintenance by the promotion of selective aggression toward alternative mates.
Monogamy is rare among mammalian species, with only 3–5% forming lifelong pair bonds. The prairie vole Microtus ochrogaster forms such enduring bonds after a single initial mating encounter, but why are these prairie-dwelling critters 'addicted to love' when their mountain- and meadow-dwelling cousins indulge in lifelong promiscuity? The answer may lie in the same neurobiological culprit already implicated in drug addiction, the neurotransmitter dopamine. A group of scientists report a role for particular dopamine receptor subtypes both in establishing pair bonds in sexually naive male prairie voles and also in maintaining the integrity of the bond after it has formed. For more information, see Nature Neuroscience 9, 7 - 8 (2006).