Increased phasic activity of VTA dopamine neurons in mice 3 weeks after repeated social defeat.

Social defeat is an ethologically relevant stress inducing neuroadaptive changes in the mesocorticolimbic dopaminergic system. Three weeks after 10 days of daily defeat salient behaviors and in vivo dopamine (DA) neuron firing were evaluated in mice. Prior defeat induced social avoidance and hyperphagia and increased ventral tegmental area (VTA) DA neuron bursting activity. These data extend previous studies and suggest that increased phasic DA neuron firing in the VTA could be considered amongst the features defining the lasting imprint of social defeat stress.