A Novel Nitronyl Nitroxide with Salicylic Acid Framework Attenuates Pain Hypersensitivity and Ectopic Neuronal Discharges in Radicular Low Back Pain

Figure 6

Repeated treatment of SANR produces antinociceptive effect on CCD-induced mechanical hypersensitivity and thermal hyperalgesia in bilateral hindpaws, which is more potent than parent nitroxide moiety Tempol and parent NSAIDs moiety aspirin. (a, c) Time course of mechanical hypersensitivity (a) and thermal hyperalgesia (c) in ipsilateral hindpaw of CCD rats before and after repeated i.p. SANR (180 μmol/kg) (red) and vehicle treatment (black). Note that ipsilateral mechanical and thermal hyperalgesia was progressively and completely reversed by SANR. (b, d) Comparison of analgesic potency in ipsilateral mechanical (b) and thermal hyperalgesia (d) produced by the same concentration of SANR, Tempol, and aspirin for 18 days. Note that SANR showed significantly stronger effect than Tempol and aspirin. (e, g) Contralateral mechanical hypersensitivity (e) and thermal hyperalgesia (g) were reduced by repeated SANR administration as well. (f, h) Comparison of the efficacy by SANR with Tempol and aspirin in inhibiting mechanical (f) and thermal hyperalgesia (h) at 18 d during continuous drug administration. All data are expressed as mean ± S.E.M. .

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