Corydalis Saxicola Bunting Total Alkaloids Inhibits Paclitaxel-Induced Peripheral Neuropathy By Regulating PKCε-TRPV1 and p38 MAPK-TRPV1 Signaling Pathways

Abstract Background: Corydalis saxicola Bunting, a traditional Chinese medicine, has been proven to work well in anti-inflammation, blood circulation improvement, hemostasis, analgesia. This study was designed to observe the effects and potential mechanism of Corydalis saxicola Bunting total alkaloids (CSBTA) on paclitaxel-induced peripheral neuropathy (PIPN). Materials and methods: Following 4 times intraperitoneal injections of paclitaxel (2 mg/kg) and intragastrically (i.g.) administrated at 30 or 120 mg/kg CSBTA, mechanical and thermal allodynia and hyperalgesia in rats were tested. After 40 days, serum was collected for the detection of PGE2, TNF-α, and IL-1β by ELISA. The L4-L6 segment spinal cord, DRG, and plantar skin were harvested, and protein and gene expression of CGRP, SP, TRPV1, p38, and PKCε were analyzed by Western-blot or RT-qPCR. Parallelly, the PIPN cell model was also established in primary DRG neurons by paclitaxel stimulation (300 nM, 5 d). We examined PGE2, TNF-α and CGRP mRNA levels, and the protein expression on the PKCε-TRPV1 and p38 MAPK-TRPV1 pathways in PIPN cell model with or without CSBTA (25 μg/ml and 50 μg/ml). Results: The results showed that CSBTA effectively ameliorated allodynia and hyperalgesia in PIPN rats, regulated the contents of cytokines and neuropeptides in different tissues and cell models. CSBTA significantly decreased the protein expression of PKCε-TRPV1 and p38 MAPK-TRPV1 signaling pathways in the spinal cord and DRG tissues in the PIPN animal model and primary DRG neurons. Conclusion: Therefore, CSBTA has a perspective therapeutic effect on the treatment of paclitaxel-induced peripheral neuropathy.