Effect of intrathecal ketamine on nitric oxide synthase activity in the spinal dorsal horn in a rat model of neuropathic pain / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of intrathecal ketamine on nitric oxide synthase (NOS)activity in the spinal dorsal horn via a rat model of sciatic constriction injury(SCI). Methods Thirty-six male SDrats weighing 160-180g were randomly divided into six groups(n = 6 in each group) group Ⅰ sham operation;group Ⅱ SCI; group Ⅲ-Ⅵ intrathecal ketamine + SCI. In group Ⅰ right sciatic nerve was exposed but noligature was placed around sciatic nerve. In group Ⅱ-Ⅵ four ligatures were placed around the right sciatic nerveand hed without obstructing the blood supply of the nerve. In group Ⅲ -Ⅵ ketamine 12. 5?g (group Ⅲ ),50?g(group Ⅳ ), 0?g (group Ⅴ ) or 300?g (group Ⅵ ) was given intrathecally 30 min before and 1,2 and 3 daysafer surgery. On the 7th and 14th day after operation thermal and mechanical hyperalgesia were measured with ice-cold water and von-Frey filaments. The animals were decapitated 14 days after SCI. The I_(4-6) lumbar spinal cordwas immediately removed and the spinal dorsal horn was dissected on ice and homogenized. The homogenate wascentrifuged at 3 500 r/min for 10 min and the protein content was determined. NOS achvity in the spinal dorsal hornwas measured using ultraviolet spectrophotometer. Results In group Ⅱ and Ⅲ pain threshold was significantlylowered and NOS activity significantly increased compared with those in group Ⅰ(sham operation) (P0 .05),but therewas signilicant difference in NOS activity between group Ⅱ and group Ⅳ, Ⅴ, Ⅵ (P