Understanding neuronal subtype-specific function of NAc in cocaine addiction

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Understanding neuronal subtype-specific function of NAc in cocaine addiction Abstract Drug addiction is a chronic, relapsing brain disorder characterized by compulsive drug seeking and use despite harmful consequences. It is an urgent social and health problem contributing to more than 90,000 deaths and incurs a yearly cost of over $700 billion in the United States (see NIDA website). It is believed that long-term maladaptive changes in the brain reward system play a central role in the development of addictive disorders. However, the underlying mechanism remains largely unknown. The long-lasting effect of drugs on animal behavior and the risk of relapse in human addicts indicate that some stable changes in the brain reward system induced by drugs of abuse mediate these long-term behavioral adaptions. Accumulating evidence suggests that drug-induced molecular, cellular and circuitry changes, especially those in the nucleus accumbens (NAc), play important roles in drug addiction. However, due to the cellular heterogeneity of the mammalian brain, the cell type-specific mechanism of addition is unknown. To overcome the cell heterogeneity issue and to advance our understanding of the cell subtype- specific mechanisms of drug addiction, we propose to identify the neuronal subtypes in NAc involved in addiction by comprehensively analyzing the transcriptional profiles of this brain region in a neuron subtype-specific manner, using a clinically relevant intravenous cocaine self-administration (IVSA) mouse model. Furthermore, cell type-specific profiling/manipulation approaches will be used to understand the function and mechanism of specific neuron subtypes during addictive process. To achieve this goal, we have the following specific aims: 1) Profile cell type-specific transcriptome of different neuron subtypes of NAc using a mouse model of cocaine IVSA; 2) The function and circuitry mechanisms of Tac2+ D1 MSN subtype in cocaine addiction; 3) Understand the epigenetic mechanism of the neuron subtype-specific functions in cocaine addiction. Completion of the proposed study will not only advance our understanding on how different NAc neuron subtypes contribute to drug addiction, but also reveal novel therapeutic targets for treating this disorder.