Friday, June 19, 2015

Ocytocin reverses amphetamine-induced deficits in social bonding.

As a followup to yesterday's post on a positive effects of amphetamine on the cognition of aging adults, I thought it would be interesting to point out a dark side of amphetamine by noting the paper by Young et al. showing reversal of amphetamine-induced social impairments by oxytocin treatment. (In addicts who fail to develop or maintain intimate relationships amphetamine appears to hijack the brain's social reward circuitry. Clinical trials in humans are indicating a clear potential for oxytocin as a treatment for addiction.) They use the prairie vole male pair bonding model.
Drug addiction has devastating consequences on social behaviors and can lead to the impairment of social bonding. Accumulating evidence indicates that alterations in oxytocin (OT) and dopamine (DA) neurotransmission within brain reward circuitry may be involved. We investigated this possibility, as well as the therapeutic potential of OT for drug-induced social deficits, using the prairie vole (Microtus ochrogaster)—a socially monogamous rodent that forms enduring pair bonds between adult mates. We demonstrate that repeated exposure to the commonly abused psychostimulant amphetamine (AMPH) inhibits the formation of partner preferences (an index of pair bonding) in female prairie voles. AMPH exposure also altered OT and DA neurotransmission in regions that mediate partner preference formation: it decreased OT and DA D2 receptor immunoreactivity in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAcc), respectively, and increased NAcc DA levels. Administration of OT directly into the mPFC of AMPH-exposed voles restored partner preferences, and altered NAcc DA levels, and this effect was dependent on OT receptor activation. Together, these data suggest that repeated AMPH exposure impairs pair bonding through an OT-mediated mechanism, and that OT and DA systems within brain reward circuitry may interact to mediate the complex relationship between drug abuse and social bonding. Further, these results provide empirical support for the idea that the central OT system may represent an important target for the treatment of social deficits in addiction.

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