Microglia morphology and proinflammatory signaling in the nucleus accumbens during nicotine withdrawal

Smoking is the largest preventable cause of death and disease in the United States. However, <5% of quit attempts are successful, underscoring the urgent need for novel therapeutics. Microglia are one untapped therapeutic target. While previous studies have shown that microglia mediate both inflammatory responses in the brain and brain plasticity, little is known regarding their role in nicotine dependence and withdrawal phenotypes. Here, we examined microglial changes in the striatum-a mesolimbic region implicated in the rewarding effects of drugs and the affective disruptions occurring during withdrawal. We show that both nicotine and withdrawal induce microglial morphological changes; however, proinflammatory effects and anxiogenic behaviors were observed only during nicotine withdrawal. Pharmacological microglial depletion during withdrawal prevented these effects. These results define differential effects of nicotine and withdrawal on inflammatory signaling in the brain, laying the groundwork for development of future smoking cessation therapeutics.