GluN2B-BDNF pathway in the cerebrospinal fluid-contacting nucleus mediates nerve injury-induced neuropathic pain in rats.

The present study was aimed to investigate the role of GluN2B-BDNF pathway in the cerebrospinal fluid-contacting nucleus (CSF-CN) in neuropathic pain. Intra-lateral ventricle injection of cholera toxin subunit B conjugated with horseradish peroxidase (CBHRP) was used to label the CSF-CN. Double-labeled immunofluorescent staining and Western blot were used to observe the expression of GluN2B and BDNF in the CSF-CN. Chronic constriction injury of sciatic nerve (CCI) rat model was used to duplicate the neuropathic pain. Pain behavior was scored to determine the analgesic effects of GluN2B antagonist Ro 25-6981 and BDNF neutralizing antibody on CCI rats. GluN2B and BDNF were expressed in the CSF-CN and their expression was up-regulated in CCI rats. Intra-lateral ventricle injection of GluN2B antagonist Ro 25-6981 or BDNF neutralizing antibody notably alleviated thermal hyperalgesia and mechanical allodynia in CCI rats. Moreover, the increased expression of BDNF protein in CCI rats was reversed by intra-lateral ventricle injection of Ro 25-6981. These results suggest that GluN2B and BDNF are expressed in the CSF-CN and alteration of GluN2B-BDNF pathway in the CSF-CN is involved in the modulation of the peripheral neuropathic pain.