Targeting neuropathic pain prevention: Modulating the neuroimmunology of peripheral nerve injury

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PROJECT SUMMARY Neuropathic pain occurs in epidemic proportions worldwide and none of the currently available therapeutics provides adequate pain relief and all have significant side effects. None are “disease modifying” as all are simply palliative in targeting symptoms, not cause. There must be a better approach to pain control. What we have discovered could potentially revolutionize the clinical treatment of trauma and surgical pa- tients, all of whom are at marked risk (~50-70%) for developing neuropathic pain. Our discovery is that 6 wk of moderate voluntary exercise that ceases at the time of nerve trauma appears to permanently suppress the lat- er development of neuropathic pain. Such an effect has never been previously reported. The core thesis of this proposal is that novel, superior pharmacological and/or herbalism treatment strate- gies will arise from understanding how non-pharmacological voluntary exercise produces dramatic prevention of chronic pain. The critical first step is to understand how VWR prevents chronic pain. This enlightens target- ed, evidence-based steps toward achieving the same dramatic prevention of pain via pharmacological and/or herbal medicine approaches. The mechanisms explored in the present proposal are unique from those of any currently available pain therapeutic. If we can understand and harness prevention of neuropathic pain, this should lead to early drug interventions of broad practical importance. How 6 wk voluntary wheel running (VWR) could profoundly influence the cascade of neuroimmunological and neuropathological events set into motion by later nerve injury has never been explored. This is critical to understand at a mechanistic level, as prior VWR appears to be the first “disease modifying” approach to con- trolling whether chronic pain develops. Understanding how this occurs will enable development of novel drug regimens to pharmacologically duplicate these effects without the necessity of exercise regimens that few peo- ple will follow. We predict that understanding how prior voluntary exercise (VWR) exerts such powerful, and seemingly permanent suppression of neuropathic pain is a tractable research goal, addressable by the multi-disciplinary approach proposed. This would first seek to understand the behavioral, immunological, neuroimmunological, and functional effects of: (a) VWR, (b) nerve injury (classic sciatic chronic constriction injury [CCI] model in male and female rats), and (c) their interaction on the aftermath of nerve injury. Based on these findings, mechanistic studies are proposed so to begin to explore how prior VWR could exert such a positive, pain- preventative effect on later nerve injury. Toward this goal, studies that seek to inhibit and to recapitulate the effects of VWR are both proposed. The long term aim is to capitalize on the understanding of how prior VWR creates such long-lasting suppression of neuropathic pain so to identify clinically relevant approaches to neu- ropathic pain prevention, thereby providing a far superior approach to pain control than currently available.