Abstract: Opiate drug abuse is a critical contributor to the global AIDS epidemic, and over a third of HIV infections in the U.S. can be linked to intravenous drug abuse. Recent estimates suggest that almost 20% of intravenous drug abusers are infected with HIV. HIV-associated neuropathy remains a clinically significant issue for patients infected with HIV, even in the current era of anti-retroviral therapy. In addition, HIV-infected opiate abusers demonstrate a more severe neuropathy than non-opiate abusers, and the basis for the greater neuropathy remains uncertain. In this application, we propose that HIV infection in the brain results in an inflammatory response, which promotes the production of inflammatory chemokines, leading to the activation of the respective chemokine receptors, resulting in the cross-desensitization of opioid receptors. The consequence of this set of events is an elevated sensitivity to pain stimuli. We propose to test these processes using mouse models to evaluate the influence of HIV gp120 in the induction of neuroinflammation, including the associated neuropathic pain. Our proposed studies will also attempt to address the ability of morphine to attenuate the development of this pain response. We also propose to confirm these studies through the analysis of an authentic HIV infection using a humanized mouse model. We believe the results from these studies will greatly enhance our understanding of the mechanisms which contribute to the development of neuroinflammation in HIV-infected subjects, including those who are opiate abusers.