Planta medica
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In this study, we evaluated the protective effects of thymoquinone, the major constituent of Nigella sativa seeds on the neuropathic pain of rats with chronic constrictive injury of the sciatic nerve. Rats received repeated administration of thymoquinone (1.25, 2.5, and 5 mg/kg, i. p.) once a day for 14 days, beginning immediately after the nerve injury. Mechanical allodynia, cold allodynia, and thermal hyperalgesia were assessed with the von Frey filament, acetone drop, or radiant heat stimulus, respectively. ⋯ Thymoquinone treatment (2.5 and 5 mg/kg) restored the levels of malondialdehyde. High dose of thymoquinone (5 mg/kg) also reversed the decreased glutathione in the injured animals. Our results indicate that, microglia, apoptotic factors, and oxidative stress rather than astroglia contribute to the pathogenesis of chronic constrictive injury, and thymoquinone plays an anti-nociceptive role possibly by antioxidant effects and inhibition of microglia activity.