Elucidating the Role of Cortical Astroglia in Heroin Seeking - Findings from rodent models of heroin self-administration (SA) and cue-induced heroin seeking demonstrate that chronic opioid exposure leads to maladaptive cortical plasticity mechanistically linked to the persistent vulnerability to relapse that characterizes opioid use disorder. Emerging data from our lab, using genetic calcium indicators (GECIs) to analyze neuronal activity and head-fixed in vivo 2-photon imaging during drug taking and subsequent drug seeking, demonstrate that unique neuronal ensembles form within the dorsomedial prefrontal cortex (dmPFC) during drug exposure, SA, and withdrawal. These data support the hypothesis that discrete neuronal ensembles encode specialized information pertaining to reward-associated cues, and reward delivery, and that these ensembles drive reward seeking behaviors in operant drug-reward learning and drug-seeking tasks. Importantly, manipulation of these ensembles serves as an effective means to reduce or eliminate cue-induced drug seeking. Despite these advances, very little is known about how dmPFC neuronal ensembles are formed and refined to control drug seeking. We hypothesize that astroglia, critical mediators of this synaptic plasticity, are required for this process. Yet very little is known about how astrocyte activity patterns adapt across reward learning and how this coincides with neuronal ensemble formation. Further, it also remains to be elucidated what role cortical astroglia play in regulating or directing the adaptations in neuronal activity driven by drug-reward learning. A growing body of evidence now indicates that astrocytes respond to altered patterns of synaptic activity by engaging mobilization of internal Ca2+ stores to drive Ca2+- mediated astroglial cellular processes that coordinate and integrate action potential firing within neuronal networks. Considering these new and exciting data, astroglia serve as an excellent candidate for a crucial regulatory force required to shape drug reward-learning neuronal ensemble formation, and as such are an underexplored research direction that could lead to viable means to limit relapse vulnerability. Our overarching hypothesis is that coordinated dmPFC astrocyte activity during heroin SA is required to shape the neuronal ensembles underlying heroin seeking. Throughout the proposal, we will employ intersectional viral vector strategies. In Aim 1 we will utilize neuronal and astroglial GECI expression and analysis pipelines to analyzed and relate activity within each cell type, and in Aim 2 we will use an intersectional approach for astroglial activation and simultaneous neuronal GECI expression and analysis. In Specific Aim 1, we will establish how neuronal and astroglial activity patterns evolve as heroin SA progresses to heroin seeking, using parallel sucrose controls. We will also specifically compare astrocytic responses to neuronal ensembles, during both heroin or sucrose taking and seeking. In Specific Aim 2, we will establish how chronic astroglial activation, via chemogenetic stimulation of Gq signaling, impacts neuronal ensemble formation during heroin or sucrose SA, extinction, and cue-induced seeking.
