BackgroundReactive oxygen species and inflammatory responses contribute to the development of neuropathic pain. Superoxide serves to mediate cell signaling processes and tissue injury during inflammation. We examined the effects of superoxide on the development and maintenance of mechanical allodynia, as well as its contribution to central sensitization in a superoxide-rich animal model of neuropathic pain.MethodsChronic post-ischemia pain (CPIP) was induced via the left hindpaw ischemia for 3 h, followed by reperfusion. Superoxide dismutase (4,000 U/kg, i.p.) was administered either 5 min before ischemia (BI), 5 min before reperfusion (BR), or 3 days after reperfusion (3AR). Withdrawal thresholds of the four paws were measured to assess the mechanical allodynia and the effects of circulating xanthine oxidase (XO)-mediated superoxide production. In addition, we measured the levels of N-methyl D-aspartate receptor subunit 1 phosphorylation (p-NR1) in the ipsilateral and contralateral spinal cord (L4-6), by Western blotting, to examine the superoxide-mediated central sensitization. Superoxide production was assessed by allopurinol-sensitive, XO-mediated lipid peroxidation of the spinal cord and gastrocnemius muscles.ResultsWithdrawal thresholds of forepaws did not vary across the 7 days of testing. In the hindpaws, both ipsilateral and contralateral mechanical allodynia was most attenuated in the BR group, followed by the BI and 3AR groups. The degree of NR1 activation was in contrast to the changes in the withdrawal thresholds.ConclusionsThese data suggest that superoxide is involved in the development and maintenance of mechanical allodynia, particularly via central sensitization in the spinal cord.
Background: The gut is an important area for inflammatory responses. Gut manipulation during open laparotomy compared with laparoscopic surgery, increases the inflammatory responses. Laparoscopic assisted colectomy (LC) with less bowel manipulation might minimize the inflammatory responses and oxidative stress, and offer a faster postanesthetic recovery than an open colectomy (OC). This study evaluated the effect of N-acetyl-cysteine (NAC), an antioxidant, on the recovery after colectomy. Methods: 116 colorectal tumor patients were reviewed retrospectively. The patients were divided into 3 groups; LC by surgeon A (A-L), OC by surgeon A (A-O) and OC by surgeon B (B-O). The postanesthetic recovery scores (PARS) were compared. In the prospective randomized controlled trial, the colorectal tumor patients were assigned to one of four groups; laparoscopic assisted colectomy (L -N) with NAC infusion (L + N), open colectomy (O-N) with NAC infusion (O + N). In the NAC groups, NAC (5 mg/kg/h) was infused after intubation to extubation. The PARS were compared.Results: In the retrospective study, the time to reach 10 points, which satisfies the discharge criteria in the PACU, was significantly lower in the A-L group than in the other groups. In the prospective study, the time to 10 points was shorter in the O + N group than in the O-N group. NAC offered no added benefits to the L + N and L-N groups.Conclusions: NAC offered faster recovery in the OC group but not in the LC group.
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