ABSTRACT
BACKGROUND: It has been reported that carnosic acid (CA) exhibits a range of biological activities including hepatoprotective, antioxidant and anti-inflammatory. However, the effect of carnosic acid in neuropathic pain remained elusive. METHODS: A neuropathic pain model of chronic constriction injury (CCI) was established in adult male Sprague-Dawley rats. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were recorded, and western blot was performed to detect sirtuin1 and p66shc content. RESULTS: Intrathecal administration of carnosic acid attenuated mechanical allodynia and thermal hyperalgesia in rats following chronic constriction injury. Interestingly, carnosic acid analgesic effect was positively associated with spinal sirtuin1 activation; however, p66shc was inhibited by carnosic acid in the spinal cord. In additional, sirtuin1 inhibitor EX-527 reversed the anti-nociceptive effect of carnosic acid. CONCLUSIONS: Carnosic acid is effective in the treatment of the established CCI-induced pain. It may be possible that spinal sirtuin1 activition by carnosic acid attenuates neuropathic pain through a mechanism involving the down-regulation of p66shc expression.
