# A comprehensive dissection of cell types, circuits and molecular adaptations during opioid use

> **NIH NIH R01** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2024 · $1,401,388

## Abstract

PROJECT SUMMARY
A major barrier in the field of opioid research is our limited understanding of the organization of the opioid system
in the brain: we still do not know which cell types express each opioid receptor (mu, delta, kappa, nociceptin) to
mediate the effects of endogenous and exogenous opioids, nor what other molecules are present in these cells.
Without this knowledge, understanding how opioids alter activity in circuits to produce behavioral effects remains
elusive. This gap in knowledge prevents the identification of molecular targets to potentiate opioid analgesia and
mitigate the deleterious effects of opioid use disorder (OUD), including addiction and respiratory depression.
 To fill this gap in knowledge, we propose to leverage the uniquely massive single-cell RNA sequencing
(scRNA-seq) database generated by the Allen Institute for Brain Science (>3.4 million cells throughout the entire
mouse brain) as part of the BRAIN Initiative Cell Census Network (BICCN) effort. Using this database, we will
establish a comprehensive catalog of all the cell types that express each opioid receptor and peptide throughout
the brain, as well as the co-expression of gene networks that mediate or regulate opioid actions, including other
G protein-coupled receptors and cellular effectors of opioid receptors (Aim 1). Further, we will use our well-
established high-throughput single-cell RNA-seq pipelines to characterize the cell-type-specific molecular
adaptations that occur during chronic opioid exposure, withdrawal, and abstinence, using a clinically relevant
model of post-surgical pain for which opioids are typically prescribed (Aim 2). Finally, we will leverage this novel
knowledge to dissect the mechanisms of action of opioids by performing advanced circuit mapping and in vivo
functional imaging studies of cell types expressing opioid receptors in the prefrontal cortex (PFC), a region critical
to both opioid analgesia and addiction (Aim 3).
 Our transformative work will be the first to combine several highly innovative technologies at the
molecular, circuit, and neural ensemble levels, including high-throughput scRNA-seq, new viral strains with
improved transsynaptic transfer and decreased toxicity for circuit mapping, the crystal skull and miniscope-
microprism optical approaches for in vivo wide-field imaging of brain state and for recording dynamics of
molecularly defined neuron types in freely moving mice undergoing opioid analgesia and addiction paradigms.
 We have an extraordinary interdisciplinary team of investigators with highly complementary expertise in
the neurobiology of opioids and the distribution and function of their receptors in pain and addiction circuits, the
molecular and anatomical brain architecture, large-scale cell type characterization and circuit mapping, and
highly innovative brain imaging methods as applied to the study of neural circuits.
 Overall, this research aims to generate an exceptional resource for the opioid...

## Key facts

- **NIH application ID:** 10816564
- **Project number:** 5R01DA054583-04
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** MARK J SCHNITZER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $1,401,388
- **Award type:** 5
- **Project period:** 2021-06-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10816564

## Citation

> US National Institutes of Health, RePORTER application 10816564, A comprehensive dissection of cell types, circuits and molecular adaptations during opioid use (5R01DA054583-04). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/10816564. Licensed CC0.

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