COX2 expression in the spinal cord of nCOX2–/– mice after peripheral inflammation.
(A) After peripheral inflammation, spinal Cox2 mRNA levels are significantly increased in control animals (*P < 0.05, **P < 0.01, n = 4–5, 1-way ANOVA with Dunnett’s procedure). In contrast, a smaller but nonsignificant increase in spinal Cox2 mRNA expression is detected in nCOX2–/– mice (P > 0.05, n = 4–5; mean ± SEM). (B) Immunohistochemical study of COX2 expression in the dorsal horn of L4–L5 from control and nCOX2–/– mice. After peripheral inflammation (24 hours after CFA), COX2 expression is induced in the ipsilateral dorsal horn (dotted line) of control but not nCOX2–/– mice. NeuN is used as a neuronal marker in the bottom row. Scale bars: 50 μm. (C and D) Western blots show induction of COX2 in the spinal cord of control animals after CFA injection (**P < 0.01, n = 3, Student’s t test), whereas little or no COX2 protein is found in nCOX2–/– mice. GAPDH is used as internal control (mean ± SEM).