High frequency DBS-like optogenetic stimulation of nucleus accumbens dopamine D2 receptor-containing neurons attenuates cocaine reinstatement in male rats

Abstract

BackgroundPrevious work indicated that deep brain stimulation (DBS) of the nucleus accumbens shell in male rats attenuated reinstatement of cocaine seeking, an animal model of craving. However, the potential differential impact of DBS on specific populations of neurons to drive the suppression of cocaine seeking is unknown. Medium spiny neurons in the nucleus accumbens are differentiated by expression of dopamine D1 receptors (D1DRs) or D2DRs, activation of which promotes or inhibits cocaine-related behaviors, respectively. The advent of transgenic rat lines expressing Cre recombinase selectively in D1DR-containing or D2DR-containing neurons, when coupled with Cre-dependent virally mediated gene transfer of channelrhodopsin (ChR2), enabled mimicry of DBS in a selective subpopulation of neurons during complex tasks. HypothesisWe tested the hypothesis that high frequency DBS-like optogenetic stimulation of D1DR-containing neurons in the accumbens shell would potentiate, whereas stimulation of D2DR-containing neurons in the accumbens shell would attenuate, cocaine-primed reinstatement of cocaine seeking. ResultsResults indicated that high frequency, DBS-like optogenetic stimulation of D2DR-containing neurons attenuated reinstatement of cocaine seeking in male rats, whereas DBS-like optogenetic stimulation of D1DR-containing neurons did not alter cocaine-primed reinstatement. Surprisingly, DBS-like optogenetic stimulation did not alter reinstatement of cocaine seeking in female rats. In rats which only expressed eYFP, intra-accumbens optogenetic stimulation did not alter cocaine reinstatement relative to sham stimulation, indicating that the effect of DBS-like stimulation to attenuate cocaine reinstatement is mediated specifically by ChR2 rather than consequent to prolonged light delivery. ConclusionsThese results suggest that DBS of the accumbens attenuates cocaine-primed reinstatement in male rats through the selective manipulation of D2DR-containing neurons.