Single-nucleus transcriptomics in rat striatum following morphine administration and withdrawal

阿片类药物使用障碍（OUD）是美国持续的公共卫生危机。尽管

Opioid use disorder (OUD) is an ongoing public health crisis in the United States. Despite the effectiveness of current medications to treat OUD, there is still a high rate of relapse following detoxification. Thus, there is a critical need for a better understanding of the neurobiological mechanisms contributing to opioid taking and seeking that could lead to novel targets for future OUD treatments. An emerging literature studying the effects of opioids on human and rodent neural transcriptomes has identified alterations in gene expression in multiple brain regions. However, these studies are limited by bulk transcriptomic approaches, which prevent assignment of expression changes to specific neuronal or glial cell types. Single nucleus RNA sequencing (snRNAseq) approaches have the potential to address this knowledge gap and identify cell type-specific transcriptomic alterations that will advance our understanding of the pathophysiology of OUD. A recent snRNAseq study characterized the effects of an acute experimenter-delivered morphine injection on cell type-specific transcriptomes in the mouse nucleus accumbens (NAc), a brain region that plays a critical role in drug-taking and -seeking behaviors. Our preliminary studies extended these results by using snRNAseq to perform differential gene expression analysis in distinct NAc cell populations and subtypes following acute morphine injection or repeated morphine self-administration. Our exciting results reveal, for the first time, novel cell type- specific transcriptomic changes in the NAc that are associated with the escalation of voluntary opioid taking. A logical next step for the field is to determine the effects of sex on single nuclei transcriptomes as well as profile longitudinal changes in gene expression throughout subsequent abstinence periods. Therefore, one goal of this proposal is to characterize the sex- and cell type-specific effects of acute morphine exposure and volitional morphine taking in the rat NAc (Aim 1). One cohort of female Sprague-Dawley rats will receive an intraperitoneal injection of morphine or saline. A second cohort of female rats will be paired with yoked saline controls and allowed to self-administer morphine for 10 days, a period in which escalation of opioid taking develops. snRNAseq will then be used to identify sex-specific and sex-independent cell type-specific differentially expressed genes in the NAc. To comprehensively profile changes in gene expression throughout abstinence following morphine self-administration, snRNAseq will be used to analyze sex- and cell type-specific transcriptomic changes following acute (1 day) and prolonged (10 days) of opioid abstinence. Differentially expressed genes from each aim will be validated by fluorescent in situ hybridization (FISH) and RNAscope. This proposal will advance preclinical OUD research by using a snRNAseq approach to identify sex- and cell type- specific NAc transcriptome alterations associated with opioid taking and withdrawal thereby identifying novel therapeutic targets that will help guide the development of new medications to treat OUD.