Grant: Operating Grant

One category of chronic pain that is particularly challenging to treat is neuropathic pain; pain caused by damage or dysfunction to the nervous system. In addition to the obvious sensory disturbances that accompany neuropathic pain, this condition is associated with an important affective or emotional component. The negative affect, or how much the pain is bothersome significantly impacts quality of life, and leads to the common co-morbidities of psychiatric disorders such as depression; patients with NP pain are twice as likely to suffer from depression and anxiety. Our preliminary data suggest that the brain circuitry recruited for opioid-induced reward is different in neuropathic compared to pain-naive animals. This difference appears to involve non-neuronal glia cells in brain regions important for emotion. Our proposed research will test the hypothesis that neuropathic pain causes activation of non-neuronal cells, microglia, in brain regions important for pleasure and reward. We will use a multidisciplinary approach consisting of behavioral, biochemical, pharmacological, and morphological techniques in a rodent model of neuropathic pain to investigate how opioid reward circuitry is changed in such chronic pain states. The specific aims will determine the contribution of microglia cell involvement and the circuitry in opioid reward in neuropathic animals.