Fig. 1.
Spinal nerve ligation (SNL) up-regulates growth arrest and DNA-damage–inducible protein 45β (Gadd45β) expression in spinal dorsal horn neurons, accompanied by behavioral allodynia. (A) Representative Western blot and statistical analysis (normalized to glyceraldehyde 3-phosphate dehydrogenase protein [GAPDH]) revealing that whereas sham operation (Sham) exhibited no effect, SNL increased the abundance of Gadd45β on days 3, 7, 14, and 21 postoperation specifically in the ipsilateral (I and IPSI), but not the contralateral (C and CONTRA), dorsal horn. **P < 0.01 versus Sham IPSI. #P < 0.05. ##P < 0.01 versus SNL day −1. n = 6. (B) The withdrawal threshold of the ipsilateral (SNL IPSI), but not the contralateral (SNL CONTRA), hind paw decreased on days 3, 7, 14, and 21 after SNL (von Frey test). **P < 0.01 versus Sham IPSI. ##P < 0.01 versus SNL day −1. n = 7. (C) In the ipsilateral dorsal horn (IPSI), SNL (SNL 7D) increased the immunofluorescence of Gadd45β (red; IV and V), which colocalized (yellow) with neuronal (NeuN, a marker of neurons; green; VII and X) but not microglial (OX-42, a marker of microglia; green; VIII and XI) or astrocyte (glial fibrillary acidic protein, a marker of astrocytes; green; IX and XII) markers, on day 7 postoperation. Scale bar = 50 μm. Thickness = 50 μm. **P < 0.01 versus Sham IPSI. ##P < 0.01 versus SNL CONTRA. n = 7. Data represent mean ± SD. IB = immunoblotting.