Effect of propofol the expression of inducible nitric oxide synthase in the spinal cord in rats with chronic neuropathic pain

Objective To investigate the effects of propofol the expression of inducible nitric oxide synthase (iNOS) in the spinal cord in rats with chronic neuropathic pain. Methods Forty adult Wistar rats of both sexes weighing 200-220 g were used in this study. Chronic neuropathic pain was produced by loose ligatures placed on the left sciatic nerve. Propofol or normal saline (NS) was given intraperitoneally (i.p. ) once a day for 6 days, seven days after sciatic nerve ligation. The animals were randomly divided into 4 groups (n = 10) : group Ⅰreceived NS 50 ml·kg-1 i.p. but no sciatic nerve ligation; group Ⅱ received sciatic nerve ligation and NS 50 ml·kg-1 i.p. ; group Ⅲ and Ⅳ received sciatic nerve ligation and propofol 50ml·kg-1 (Ⅲ) or75ml·kg-1 (Ⅳ) i.p. . Withdrawal threshold of both hind paws to Von Frey filaments was measured on the 6th , 10th and 12th days after sciatic nerve ligation. The animals were then sacrificed and the lumbar segment (L4-5) of the spinal cord was removed for the detection of iNOS mRNA expression by RT-PCR technique on the 12th day. Results The withdrawal threshold to Von Frey filament of both hind paws was significantly higher on the 10th and 12th days in the two propofol groups (group Ⅲ and Ⅳ) than in group Ⅱ(P 0.05) . The expression of iNOS mRNA in group Ⅲ and Ⅳ was significantly lower than that in group n (P 0.05) . Conclusion The antinociceptive effect of propofol is closely related to its inhibitory action on expression of iNOS mRNA in the spinal cord.