Single Cell RNAseq Uncovers a Robust Transcriptional Response to Morphine by Glia

Molecular and behavioral responses to opioids are thought to be primarily mediated by neurons, although there is accumulating evidence that other cell types play a prominent role in drug addiction. To investigate cell-type-specific opioid responses, we performed single-cell RNA sequencing of the nucleus accumbens of mice following acute morphine treatment.  Differential expression analysis uncovered unique morphine-dependent transcriptional responses by oligodendrocytes and astrocytes. Further analysis using RNAseq of FACS-purified oligodendrocytes revealed a large cohort of morphine-regulated genes. Importantly, the affected genes are enriched for roles in cellular pathways intimately linked to oligodendrocyte maturation and myelination, including the unfolded protein response. Altogether, our data illuminate the morphine-dependent transcriptional response by oligodendrocytes and offer mechanistic insights into myelination defects associated with opioid abuse. For single-cell experiments, we perfoed Drop-seq on 4 biological replicates each of the nucleus accumbens from saline- or morphine-treated mice. For bulk RNAseq experiments, we performed FACS to purify oligodendrocytes from the entire brains of 6 mice (3 mock, 3 morphine), then isolated RNA and subjected to RNA sequencing.