Effect of Xylopic Acid on Paclitaxel-induced Neuropathic pain in rats
Xylopic acid, a diterpenoid isolated from the fruits of Xylopia aethiopica has demonstrated analge-sic properties in acute pain models. It was therefore evaluated for its analgesic properties in paclitaxel-induced neuropathic pain, a type of pain difficult to treat clinically. Neuropathic pain was induced in rats by injecting 2 mg kg-1 of paclitaxel on alternative days for four days (days 0, 2, 4 and 6). Paclitaxel-induced cold allodynia, mechanical hyperalgesia and thermal hyperalgesia were measured during pre-paclitaxel administration and on day 16 post-paclitaxel administration. The rats were treated with xylopic acid (10, 30 and 100 mg kg-1; groups 1-3), pregabalin (10, 30 and 100 mg kg-1; groups 4-6) and vehicle (group 7) daily for 5 days. Pain thresholds were also measured daily for 5 days in the three models. Xylopic acid and pregabalin produced analgesic properties seen as increased paw withdrawal latencies to mechanical and cold water stimuli during the five days treatment. In addition, the two agents significantly (P<0.05) exhibited analgesic properties in the thermal hyperalgesia test. These data suggest that xylopic acid is an effective agent against paclitaxel-induced neuropathic pain.
Keywords: Xylopic acid, paclitaxel, neuropathic, pregabalin, hyperalgesia, cold allodynia