Spinal sample showing p-JNK and P38 associated with the pain signaling transduction of glial cell in neuropathic pain.

Abstract

To investigate the signaling pathways after astrocytes were activated in neuropathic pain. Thirty-six Sprague Dawley (s.d.) rats were randomly divided into two groups (each group with 18 s.d. rats) including chronic constriction injury (CCI) of the sciatic nerve model group and sham operation group. Operation was perform ed on the right leg in all rats. The lumbar spin al cord (L4 and L5) was taken to make paraffin slices on the 1st day before operation and the 1st, 3rd, 7th, 14th and 28th day after operation in each group. Paraffin slices were labeled with p38 mitogen-activated protein kinase (p38MAPK) and c-Jun N-terminal kinase (JNK) by immunofluorescence staining, and then were co-labeled with hexaribonucleotide binding protein-3 (NeuN), glial fibrillary acidic protein (GFAP) and anti-integrin αM (CD11b) antibody (OX-42) to explore the associations of p38MAPK and JNK with nerve cells or glial cell. Compared with sham group, the pain threshold was significantly decreased, and astrocyte-activated markers, GFAP and vimentin were significantly increased in CCI group. The mean fluorescence intensities of p38MAPK and JNK were increased in the right spinal dorsal horn of CCI group. The coexpression of JNK and GFAP was found in astrocytes of the spinal dorsal horn in CCI group. JNK signal transduction pathway is involved in the pain signaling transduction of astrocytes.