Nociceptive and Opioidergic Cell-types, Circuitry, and Function in the Cingulate Cortex

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      Pain is an unpleasant emotional experience driven by the transformation of sensory neural signals into affective-cognitive information in cortical regions, including the anterior cingulate cortex (ACC). Opioid action in the ACC ameliorates aspects of the aversive quality of pain through mu opioid receptors (MOR). We hypothesized that MOR-expressing and functionally nociceptive ACC neurons represents a crucial neural circuit cell-type to pain affect and pathological attention to chronic pain. Using single nuclei RNA sequencing of murine ACC, we found that three cell-subtypes of Slc17a7 glutamatergic neurons were the most transcriptionally active to noxious stimuli (identified by weighted expression of 139 immediate early genes (IEGs)) and differential gene expression analysis between nuclei from uninjured and chronic neuropathic pain mice. These cell-subtypes all co-expressed Oprm1 with single genetic identifiers—Otof, Figf, Npr3—that we spatially resolved to label layer-specific ensembles in L2/3 IT, L5 ET, and L5 PT neurons, respectively. To gain genetic access to ACC nociceptive-Oprm1 ensembles, we developed an intersectional approach combining genetic elements of IEGs and Oprm1 with retrograde viral recombinases to drive expression of circuit mapping tools and optogenetic actuators with activity-, molecular-, and projection-dependency. We are beginning to mimic opioid analgesia with optical inhibition of ACC MOR+ nociceptive cell-types with an iC++ opsin, while capturing pain-related behaviors with a novel deep-learning system for unbiased pose-estimation of nocifensive behaviors. Our unpublished work will provide additional insight into the input connectivity from subcortical structures and the output projection map of the nociceptive ACC cell-types. Key among these is a possible reciprocal circuit between a subpopulation of medial basolateral amygdalar nociceptive cells and ACC L2 Otof+ cells. Identifying the local cortical and brain-wide structure of specific cell-type networks underlying opioid analgesia can aid the development of circuit targeted treatments with improved selectivity, safety, and lowered addiction liabilities. Grant support from 1DP2GM140923-01 - Harnessing cortical neuromodulation to disrupt pain perception Whitehall Foundation Award in Neurobiology - Integrative cortical circuits encoding attention to pain 1 F32 DA053099-01 (Nora McCall, Corder Lab postdoc) - Modulating pain through cortical endogenous opioid circuits.
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