To evaluate the role of Sonic hedgehog (Shh) signaling pathway in the spinal cord in neuropathic pain (NP) in the rats.

Seventy-two male Sprague-Dawley rats, aged 8 weeks, weighing 250-300 g, were randomly divided into 2 groups (n=36 each) using a random number table: sham operation group (S group) and NP group.Spared nerve injury was produced by exposing the sciatic nerve and its branches and ligation and transection of tibial nerve and common fibular nerve in anesthetized rats.The mechanical paw withdrawal threshold (MWT) was measured before operation and at 1, 4, 7, 14 and 21 days after operation.After measurement of the pain threshold at 1, 4, 7, 14 and 21 days after operation, the animals were then sacrificed, and the lumbar segment (L_4-6) of the spinal cord was obtained for determination of Shh, Patched(Ptch), Gli1 and glial fibrillary acidic protein (GFAP) expression (by Western blot), Shh, Ptch and Gli1 mRNA expression (by fluorescent quantitative real-time reverse transcriptase-polymerase chain reaction), and Shh and GFAP expression (by immunohistochemistry).

Compared with group S, the MWT was significantly decreased, and the expression of Shh, Ptch and Gli1 protein and mRNA and GFAP in spinal cord tissues was up-regulated in group NP (P<0.05). Shh was mainly expressed in the cytoplasm of spinal dorsal horn neurons and in the gap around glial cells.

Shh signaling pathway in spinal cord is involved in the development and maintenance of NP in the rats.

Hedgehog proteins; Signal transduction; Neuralgia; Spinal cord