Preclinical Evidence for Intersectional Impacts of HIV and Cocaine Use Disorders on Behavior and Neuroimmune Function

Cocaine use disorders (CUDs) and human immunodeficiency virus (HIV) are a common comorbidity, although it is largely unknown whether HIV interacts with cocaine abstinence to uniquely alter neuroimmune function and whether HIV may modulate the efficacy of medications intended to treat CUDs. My dissertation research demonstrates using preclinical rodent models of drug self-administration and craving that systemic exposure to the HIV protein gp120 produces a unique profile of neuroimmune changes within the nucleus accumbens core (NAc core) that is distinct from early cocaine abstinence alone. After a protracted period of abstinence, gp120 exposure abolished the effect of the dopamine D3 receptor (D3R) partial agonist MC-25-41, which successfully attenuated cue-induced cocaine seeking in non-exposed rats. Further probing the role of downstream, intracellular neuroimmune function on cue-induced cocaine seeking, I examined the role of the nuclear factor kappa B (NF-κB) signaling pathway within the NAc core on cue-induced cocaine seeking after a period of protracted abstinence across sex and reinforcer type. I demonstrated that knockdown of the p65 subunit of NF-κB results in a decrease in cue-induced cocaine seeking in males, but not in females. This effect was specific to cocaine, as p65 knockdown did not affect cue-induced sucrose seeking in either males or females. Moreover, I examined expression levels of the extracellular matrix enzyme MMP-9 within the NAc core, as it is regulated by NF-κB and is an important mediator of cue-induced cocaine seeking and associated synaptic plasticity. I demonstrated that males express higher levels of MMP-9 within the NAc compared to females, and that p65 knockdown decreases NAc core MMP-9 in males but not females among cocaine cue-exposed animals. Altogether, these results suggest that immunotherapeutic medications may be useful tools in the treatment of CUDs, particularly among males that are disproportionately impacted by HIV.