ABSTRACT
Diabetic peripheral neuropathic pain (DPNP) is a common and intractable complication of diabetes. Conventional therapies are always not ideal; development of novel drugs is still needed to achieve better pain relief. Recent evidences have demonstrated that inflammation is involved in the onset and maintenance of DPNP. The anti-inflammatory property of Tanshinone IIA (TIIA) makes it a promising candidate to block or alter the pain perception. This study was conducted to investigate whether TIIA could attenuate DPNP in streptozotocin- (STZ-) induced rats model and its potential mechanisms. TIIA was administered to STZ-induced diabetic rats at the dose of 40 mg/kg once a day for 3 weeks. The effects of TIIA on thermal hyperalgesia and mechanical allodynia were investigated using behavioral tests. The mRNA level and expression of interleukin- (IL-) 1ß, interleukin- (IL-) 6, tumor necrosis factor- (TNF-) α, and interleukin- (IL-) 10 in the fourth to sixth segments of the dorsal root ganglion (L4-6 DRG) were detected by quantitative real-time PCR (qPCR) and Western blot. TIIA treatment significantly attenuated mechanical allodynia and thermal hyperalgesia in diabetic rats. In addition, the expression of the proinflammatory cytokines IL-1ß, IL-6, and TNF-α was inhibited, and the level of the anti-inflammatory cytokine IL-10 was increased by TIIA. This study demonstrated that TIIA has significant antiallodynic and antihyperalgesic effects in a rat model of STZ-induced DPNP, and the effect may be associated with its anti-inflammation property.
ABSTRACT
Danhong injection (DHI) has been widely used in China for cardiocerebrovascular diseases treatments. And in this study, we demonstrated the therapeutic effect of DHI on experimental diabetic neuropathy for the first time. Methods. Streptozotocin- (STZ-) induced SD rats were used. In experiment 1, 4-week treatment with DHI or saline started 4 weeks after STZ injection; mechanical allodynia was measured before and every 2 weeks after STZ injection. In experiment 2, chronic intrathecal infusion of U0126 was conducted during the 8th week of diabetes. Phosphorylated and total ERK1/2 in spinal cord were analyzed by western blot. BDNF level in sciatic nerve was evaluated by ELISA. Results. DHI treatment significantly alleviated mechanical allodynia at the end of the study and downregulated the expression of phosphorylated ERK1/2 in spinal cord. In addition, DHI treatment also elevated brain-derived neurotrophic factor (BDNF) level in sciatic nerve of DPN rat. In experiment 2, inhibition of ERK1/2 activation was confirmed to result in the alleviation of mechanical allodynia. Conclusions. We demonstrated that DHI was able to alleviate mechanical allodynia in diabetic neuropathy rat through inhibiting the activation of ERK1/2. The reduction of BDNF content in sciatic nerve was also partially reversed by DHI treatment.
ABSTRACT
OBJECTIVE: To study the anti-inflammatory mechanism of geniposide and observe the effect of geniposide on the expression of Toll-like receptor 4 (TLR4), the activity of NF-κB, and the release of pro-inflammatory cytokines- TNF-α, IL-1, and IL-6-in the RAW264.7 macrophages treated with lipopolysaccharide (LPS). METHODS: There were three experimental groups, including the control group, LPS group and LPS combined with geniposide group in this study. RAW264.7 macrophage cells were treated with LPS to induce cellular inflammation. Cell proliferation was measured by CCK-8. The concentrations of TNF-α, IL-1, and IL-6 in cell culture media were measured by ELISA. mRNA levels of TLR4 and P65 were examined by real-time PCR. The protein levels of p-IκB, P65, p-P65 and TLR4 were detected by Western blotting. RESULTS: Geniposide had no effect on cell proliferation. However, geniposide down-regulated the expression of TNF-α, IL-1, and IL-6, and also inhibited the expression of TLR4 and the activity of NF-κB. CONCLUSION: Geniposide exerts its anti-inflammatory effect through inhibiting the activity of NF-κB in the TLR4-NF-κB pathway in macrophages.
