Investigating the role of microglia molecular rhythms in the nucleus accumbens in OUD

ABSTRACT Substance use disorder is a chronic relapsing disease that is characterized by repeated drug use despite negative consequences. Despite extensive efforts into examining the underlying molecular mechanisms of methamphetamine use disorder, there are currently no FDA approved therapeutics to treat this debilitating disease. Repeated methamphetamine (METH) use induces long-term gene expression changes in brain regions associated with reward processing and drug-seeking behavior, and recent evidence suggests that METH- induced neuroinflammation may also be involved in behavioral and molecular responses to the drug. Microglia, the resident immune cells in the brain, are principal drivers of neuroinflammatory responses, yet the role of these cells in the regulation of METH-related behaviors is poorly understood. In this proposal, I will examine microglial gene expression dynamics during METH-taking and seeking using a mouse model of intravenous methamphetamine self-administration (METH IVSA) and multi-omic molecular analyses. Preliminary data in Aim 1 (F99) demonstrate that microglia respond to METH-exposure by inducing neuroinflammatory gene expression and, accordingly, changing their cellular morphology. Additionally, since our preliminary results suggest that depletion of microglia attenuates drug-seeking after prolonged abstinence, I propose to further investigate the transcriptional and epigenetic changes in microglia in response to METH-taking and during METH craving and seeking. To this end, microglia will be isolated from METH IVSA for RNA sequencing analysis and chromatin profiling using CUT&Tag (F99). For this, I will be trained to isolate microglia for RNA and chromatin extraction, as well as the downstream bioinformatic pipelines required for data analysis. For Aim 2 (K00), I will identify a postdoctoral mentor with whom to study the effect of early life stress on microglia that contribute to later life susceptibility to psychiatric and substance use disorders. These studies will sharpen our understanding of the microglial transcriptome and epigenome during METH reinforcement and how these cells influence METH-taking and seeking behavior, while also fostering my development into a postdoctoral scholar, and ultimately for a successful career as an independent investigator in an academic tenure-track position.