Mechanism of Mongolian drug Naru-3 in initiation of neuroinflammation of neuropathic pain from MMP9/IL-1β signaling pathway / 中国中药杂志

Neuropathic pain(NP) has similar phenotypes but different sequential neuroinflammatory mechanisms in the pathological process. It is of great significance to inhibit the initiation of neuroinflammation, which has become a new direction of NP treatment and drug development in recent years. Mongolian drug Naru-3 is clinically effective in the treatment of trigeminal neuralgia, sciatica, and other NPs in a short time, but its pharmacodynamic characteristics and mechanism of analgesia are still unclear. In this study, a spinal nerve ligation(SNL) model simulating clinical peripheral nerve injury was established and the efficacy and mechanism of Naru-3 in the treatment of NPs was discussed by means of behavioral detection, side effect evaluation, network analysis, and experimental verification. Pharmacodynamic results showed that Naru-3 increased the basic pain sensitivity threshold(mechanical hyperalgesia and thermal radiation hyperalgesia) in the initiation of SNL in animals and relieved spontaneous pain, however, there was no significant effect on the basic pain sensitivity threshold and motor coordination function of normal animals under physiological and pathological conditions. Meanwhile, the results of primary screening of target tissues showed that Naru-3 inhibited the second phase of injury-induced nociceptive response of formalin test in mice and reduced the expression of inflammatory factors in the spinal cord. Network analysis discovered that Naru-3 had synergy in the treatment of NP, and its mechanism was associated with core targets such as matrix metalloproteinase-9(MMP9) and interleukin-1β(IL-1β). The experiment further took the dorsal root ganglion(DRG) and the stage of patho-logical spinal cord as the research objects, focusing on the core targets of inducing microglial neuroinflammation. By means of Western blot, immunofluorescence, agonists, antagonists, behavior, etc., the mechanism of Naru-3 in exerting NP analgesia may be related to the negative regulation of the MMP9/IL-1β signaling pathway-mediated microglia p38/IL-1β inflammatory loop in the activation phase. The relevant research enriches the biological connotation of Naru-3 in the treatment of NP and provides references for clinical rational drug use.

Investigation on the inflammation network mechanisms of Wutou decoction acting on neuropathic pain / 药学学报

Wu-tou decoction (WTD) was originally recorded in the synopsis of the golden chamber and it had been widely used for the treatment of neuropathic pain (NP) with exact therapeutic efficacy. However, the underlying molecular mechanisms still remain unclarified. Thus, in this research, we aimed at clarifying the underlying molecular mechanisms of WTD against NP by combining network analysis and experimental validation based on the spinal nerve ligation (SNL) model. Firstly, the network analysis indicated that key targets of WTD were significantly involved in the MAPK signaling pathway (P = 4.04E-12) and four important components of the above pathway, AKT kinase (AKT), MAP kinase kinase 4 (MKK4), c-Jun N-terminal kinase (JNK) and transcription factor AP-1 (JUN) had been reported to play a vital role in neuroinflammation during the disease process of NP. Then, experimental validation results proved that WTD markedly reduce the severity of mechanical allodynia (P<0.01) and cold hypersensitivity (P<0.05) of SNL rats. In addition, Western blot results provided evidence that the phosphorylated protein expression levels of AKT, MKK4, JNK and JUN in the superficial lamina of spinal cord of SNL rats were markedly increased (P<0.001), and WTD could improve the phosphorylated protein expression level of AKT (P<0.001) which was reported to be nerve protective and attenuate the phosphorylated protein expression levels of MKK4, JNK and JUN (P<0.01) which were closely involved into neuroinflammation. In conclusion, this study indicated that WTD might exert anti-hyperalgesia action through the inhibition of neuroinflammation mediated by AKT-MKK4-JNK-JUN which belong to the MAPK signaling pathway. These findings also provided scientific evidences that WTD might be a promising candidate for NP. Animal experiments in this study were approved by the Ethics Committee of Experimental Animals of the China Academy of Chinese Medical Sciences.