RESUMO
Objective: To investigate the analgesic mechanism of Tuina (Chinese therapeutic massage) by observing the effect of the N-methyl-D-aspartate receptor subunit 2B (NR2B)/postsynaptic density-95 (PSD-95) pathway on the dendritic structure of spinal cord dorsal horn in rats with lumbar disc herniation. Methods: Fifty Sprague-Dawley rats were randomly divided into a blank group, a model group, a Tuina group, a blocker agent group, and a blocker agent + Tuina group. The sciatic nerve chronic constriction injury (CCI) model was prepared by the sciatic nerve ligation method. From the 4th day after modeling, rats in the Tuina group and the blocker agent + Tuina group were subject to daily Tuina intervention, and those in the blocker agent group and the blocker agent + Tuina group were daily intrathecally injected with NR2B blocker agent (MK-801). The spontaneous pain score was used to observe the pain behavior of all rats. The expression levels of NR2B and downstream PSD-95 were measured by immunohistochemistry, and the dendritic structure changes were observed by Golgi staining for rat spinal cord dorsal horn after 14 d of continuous intervention. Results: Compared with the blank group, the degree of rat spontaneous pain after CCI was elevated in both the model and the Tuina groups (P<0.01) and was reduced in the Tuina group after the Tuina intervention compared with the model group (P<0.05). Compared with the model group, the rat spontaneous pain level after blocking NR2B was reduced in both the blocker agent group and the blocker agent + Tuina group (P<0.05). The NR2B and PSD-95 protein levels were significantly higher in the model group compared with the blank group (P<0.01); the total number of dendritic branches was increased (P<0.01), and the total dendritic length became longer (P<0.01) in the spinal cord dorsal horn. The rat NR2B and PSD-95 protein levels were significantly decreased in the Tuina group compared with the model group (P<0.01); the total dendritic branch number was reduced (P<0.01) and the total length was shortened (P<0.01) in the spinal cord dorsal horn. After blocking NR2B, the expression levels of NR2B and downstream PSD-95 protein were significantly lower in both the blocker agent group and the blocker agent + Tuina group compared to the model group (P<0.01). The total branch number was significantly reduced (P<0.01), and the total length was significantly shortened (P<0.01) of the dendrites in the spinal cord dorsal horn. Conclusion: Tuina may exert an analgesic effect by remodeling the dendritic structure in the spinal cord dorsal horn in rats with lumbar disc herniation, and its mechanism may be related to the inhibition of NR2B/PSD-95 signaling pathway.
RESUMO
OBJECTIVES.: Sodium salicylate (SS) is well known for its ototoxic properties that induce functional and morphological changes in the cochlea and brain. Ginkgo biloba extract (GBE) has been widely used for treatment of various neurodegenerative diseases; however, its effects on salicylate-induced ototoxicity remain unclear. Herein, we examined the effects of EGb 761 (EGb), a standard form of GBE, on the plasticity of the N-methyl-D-aspartate receptor subunit 2B (GluN2B) in the inferior colliculus (IC) following SS administration. METHODS.: Seven-week-old Sprague Dawley rats (n=24) were randomly allocated to control, SS, EGb, and EGb+SS groups. The SS group received a single intraperitoneal SS injection (350 mg/kg), the EGb group received EGb orally for 5 consecutive days (40 mg/kg), and the EGb+SS group received EGb for 5 consecutive days, followed by an SS injection. The auditory brainstem responses (ABRs) were assessed at baseline and 2 hours after SS administration. GluN2B expression was examined by Western blot and immunohistochemistry. RESULTS.: There were no significant differences in ABR threshold shifts among the groups. The expression of the GluN2B protein normalized by which of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was significantly lower in the EGb+SS group, as compared to the SS group (P=0.012). Weak and diffused GluN2B immunoreactivity was detected in the IC neural cells of the EGb+SS group, while those of the SS group exhibited strong and diffused GluN2B positivity. CONCLUSION.: EGb may play a role in regulating the GluN2B expression in the IC of salicylate-induced ototoxicity model.