ObjectiveTo investigate the role of Wnt5a in the mechanism of radiculopathy and the relation between Wnt5a and tumor necrosis factorα(TNF-α) by observing the change of the expression of Wnt5a in the rat model of chronic compression of dorsal root ganglia (CCD). MethodsA total of 192 adult male Sprague Dawley rats were allocated into 4 groups: shame group (group A, n=48), CCD group (group B, n=48), CCD+sal ine group (group C, n=48), and CCD+etanercept group (group D, n=48). An L-shaped needle (about 3.5 mm in length, 0.6 mm in diameter) was inserted into the L5 intervertebral foramen, and the dorsal root ganglia (DRG) was compressed by the needle to prepare the CCD model in groups B, C, and D, and then normal sal ine (5.5 mg/kg) or etanercept was injected intraperitoneally in groups C and D. The intervertebral foramen was exposed in group A. The mechanical pain threshold of the posterior paw was tested by the von Frey filaments at 1, 3, 5, and 7 days after operation; the expressions of Wnt5a protein and mRNA were detected at 3 and 7 days after operation by immunohistochemical staining and RT-PCR, respectively. ResultsThe mechanical pain threshold of groups B and C was significantly lower than that of groups A and D, and in group D than in group A (P < 0.05), but no significant difference was found between groups B and C (P > 0.05). The Wnt5a positive cells and the mRNA expression of Wnt5a at 7 days were significantly more than those at 3 days in groups B, C, and D (P < 0.05). The Wnt5a positive cells and the mRNA expression of Wnt5a in groups B and C were significantly more than in groups A and D, and in group D than in group A (P < 0.05), but no significant difference was shown between groups B and C (P > 0.05). ConclusionThe expression of Wnt5a in the DRG is increased after CCD. The expression of Wnt5a in the DRG is decreased after the administration of the inhibitor of TNF-α.