Free radical biology & medicine
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Free Radic. Biol. Med. · Aug 2001
A role for free radicals and nitric oxide in delayed recovery in aged rats with chronic constriction nerve injury.
Using a reversible chronic constriction injury (CCI) model of neuropathic pain, we previously demonstrated that changes in thermal hyperalgesia correlate with the changes in peripheral microvascular blood flow in the affected paw, and that recovery can be assessed by normalization of both behavioral and vascular responses. Using the same model, this study examined age-related changes in recovery after nerve injury and the involvement of free radicals and nitric oxide (NO) in these changes. Four loose, nonconstrictive ligatures were applied to the sciatic nerve in the right, mid-thigh region of young and old (3 and 24 months) Sprague Dawley rats. ⋯ The results suggest that ROS and nNO contribute to delayed recovery of injured nerves in old rats and to the maintenance of thermal hyperalgesia and the reduction in microvascular blood flow in the area innervated by the injured nerve. The results also raise the notion that possible interaction of free radicals with NO to form peroxynitrite might be responsible for such delayed recovery. Ironically, this study also reveals a positive role for free radicals in tissue repair and raises the notion that early intervention with antioxidants could exert a negative effect on repair of injured nerves.