Thymoquinone attenuates paw incision-induced spontaneous and evoked pain through anti-oxidative and anti-inflammatory mechanisms in rats.

Surgery commonly causes post-operative pain that should be alleviated to prevent complications. In addition to the use of synthetic drugs, there has been a widespread desire to use medicinal plants for surgical pain management. Thymoquinone (TQ), a constituent of Nigella sativa black seeds, exhibits a potent anti-oxidant property. Celecoxib (CLX), a potent non-steroidal anti-inflammatory drug, is widely used in pain management. In the present study, the effects of TQ and CLX on pain caused by hind paw surgical incision were compared. Fifty-six rats were divided into four groups of 14 rats as intact, vehicle, TQ, and CLX groups. In each group, six rats were planned to record pain-related behaviors on days 1 - 10 and eight rats were designed for determination of serum biochemical alterations on days 1 (four rats) and 3 (four rats) after surgery. Oral administrations of TQ and CLX at a same dose of 10.00 mg kg^-1 alleviated paw lifting number (spontaneous pain) and paw withdrawal threshold evoked by von Frey filaments on metal mesh floor, improved the decreased contents of serum total anti-oxidant capacity and superoxide dismutase, and restored the increased levels of serum malondialdehyde and tumor necrosis factor-alpha. The results suggested that TQ by employing anti-oxidant and anti-inflammatory mechanisms, might relieve the pain induced by hind paw plantar incision, being comparable with CLX.