scholarly journals Neuroprotective Effect of Salvianolic Acid A against Diabetic Peripheral Neuropathy through Modulation of Nrf2

2020 ◽  
Vol 2020 ◽  
pp. 1-22 ◽  
Author(s):  
Chunyang Xu ◽  
Biyu Hou ◽  
Ping He ◽  
Peng Ma ◽  
Xinyu Yang ◽  
...  

Oxidative stress has been recognized as the contributor to diabetic peripheral neuropathy (DPN). Antioxidant strategies have been most widely explored; nevertheless, whether antioxidants alone prevent DPN still remains inconclusive. In the present study, we established an in vitro DPN cell model for drug screening using Schwann RSC96 cells under high glucose (HG) stimulation, and we found that salvianolic acid A (SalA) mitigated HG-induced injury evidenced by cell viability and myelination. Mechanistically, SalA exhibited strong antioxidative effects by inhibiting 1,1-diphenyl-2-picrylhydrazyl (DPPH) and reducing reactive oxygen species (ROS), malondialdehyde (MDA), and oxidized glutathione (GSSG) content, as well as upregulating antioxidative enzyme mRNA expression. In addition, SalA significantly extenuated neuroinflammation with downregulated inflammatory factor mRNA expression. Furthermore, SalA improved the mitochondrial function of HG-injured Schwann cells by scavenging mitochondrial ROS, decreasing mitochondrial membrane potential (MMP), and enhancing ATP production, as well as upregulating oxidative phosphorylation gene expression. More importantly, we identified nuclear factor-E2-related factor 2 (Nrf2) as the upstream regulator which mediated protective effects of SalA on DPN. SalA directly bound to the Kelch domain of Kelch-like ECH-associated protein 1 (Keap1) and thus disrupted the interaction of Nrf2 and Keap1 predicted by LibDock of Discovery Studio. Additionally, SalA significantly inhibited Nrf2 promoter activity and downregulated Nrf2 mRNA expression but without affecting Nrf2 protein expression. Interestingly, SalA upregulated the nuclear Nrf2 expression and promoted Nrf2 nuclear translocation by high content screening assay, which was confirmed to be involved in its antiglucotoxicity effect by the knockdown of Nrf2 in RSC96 cells. In KK-Ay mice, we demonstrated that SalA could effectively improve the abnormal glucose and lipid metabolism and significantly protect against DPN by increasing the mechanical withdrawal threshold and sciatic nerve conduction velocity and restoring the ultrastructural impairment of the injured sciatic nerve induced by diabetes. Hence, SalA protected against DPN by antioxidative stress, attenuating neuroinflammation, and improving mitochondrial function via Nrf2. SalA may be prospective therapeutics for treating DPN.

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Ji-Yin Zhou ◽  
Shi-Wen Zhou

The mechanisms leading to diabetic peripheral neuropathy are complex and there is no effective drug to treat it. As an active component of several traditional Chinese medicines, trigonelline has beneficial effects on diabetes with hyperlipidemia. The protective effects and the mechanism of trigonelline on diabetic peripheral neuropathy were evaluated in streptozotocin- and high-carbohydrate/high-fat diet-induced diabetic rats. Rats were divided into four groups at the end of week 2: control, diabetes, diabetes + trigonelline (40 mg/kg), and diabetes + sitagliptin (4 mg/kg). After 48-week treatment, technologies of nerve conduction, cold and hot immersion test, transmission electron microscopy, real-time PCR, and Western blotting were applied. Serum glucose, serum insulin, insulin sensitivity index, lipid parameters, body weight, sciatic nerve conduction velocity, nociception, glucagon-like peptide-1 receptor mRNA and protein, total and phosphorylated p38 mitogen-activated protein kinases protein expression, malonaldehyde content, and superoxide dismutase activity were altered in diabetic rats, and were near control levels treated with trigonelline. Slight micropathological changes existed in sciatic nerve of trigonelline-treated diabetic rats. These findings suggest that trigonelline has beneficial effects for diabetic peripheral neuropathy through glucagon-like peptide-1 receptor/p38 mitogen-activated protein kinases signaling pathway, nerve conduction velocity, antioxidant enzyme activity, improving micropathological changes of sciatic nerve and decreasing lipid peroxidation.


2021 ◽  
Vol 12 ◽  
Author(s):  
Jiayue Zhu ◽  
Xinwei Yang ◽  
Xiao Li ◽  
Shuo Han ◽  
Yanbo Zhu ◽  
...  

Tang Luo Ning (TLN), a traditional Chinese compound prescription, has been used clinically to treat diabetic peripheral neuropathy (DPN) in China. However, the exact mechanisms remain unclear. The objective of this study is to unravel the effects of TLN on mitochondrial dynamics of DPN in streptozotocin-induced rat models and Schwann cells cultured in 150 mM glucose. Mitochondrial function was determined by Ca2+ and ATP levels of streptozotocin (STZ)-induced DPN rats and mitochondria structure, mitochondrial membrane potential (MMP), and mtDNA of high glucose incubated SCs. Mitochondrial dynamics protein including mitofusin 1 (Mfn1), mitofusin 2 (Mfn2), optic atrophy 1 (Opa1), and dynamin-related protein 1 (Drp1) were investigated using Western blot or immunofluorescence. Myelin basic protein (MBP), myelin protein zero (MPZ), and sex-determining region Y (SRY)-box 10 (Sox10) were measured to represent schwannopathy. Our results showed that TLN increased ATP levels (0.38 of model, 0.69 of HTLN, 0.61 of LTLN, P<0.01; 0.52 of 150 mM glucose, 1.00 of 10% TLN, P<0.01, 0.94 of 1% TLN, P<0.05), MMP (0.56 of 150 mM glucose, P<0.01, 0.75 of 10% TLN, P<0.05, 0.83 of 1% TLN, P<0.01), and mtDNA (0.32 of 150 mM glucose, 0.43 of 10% TLN, P<0.01) while decreased Ca2+ (1.54 of model, 1.06 of HTLN, 0.96 of LTLN, P<0.01) to improve mitochondrial function in vivo and in vitro. TLN helps maintain balance of mitochondrial dynamics: it reduces the mitochondria number (1.60 of 150 mM glucose, 1.10 of 10% TLN, P<0.01) and increases the mitochondria coverage (0.51 of 150 mM glucose, 0.80 of 10% TLN, 0.87 of 1% TLN, P<0.01), mitochondrial network size (0.51 of 150 mM glucose, 0.95 of 10% TLN, 0.94 of 1% TLN, P<0.01), and branch length (0.63 of 150 mM glucose, P<0.01, 0.73 of 10% TLN, P<0.05, 0.78 of 1% TLN, P<0.01). Further, mitochondrial dynamics–related Mfn1 (0.47 of model, 0.82 of HTLN, 0.77 of LTLN, P<0.01; 0.42 of 150 mM glucose, 0.56 of 10% TLN, 0.57 of 1% TLN, P<0.01), Mfn2 (0.40 of model, 0.84 of HTLN, 0.63 of LTLN, P<0.01; 0.46 of 150 mM glucose, 1.40 of 10% TLN, 1.40 of 1% TLN, P<0.01), and Opa1 (0.58 of model, 0.71 of HTLN, 0.90 of LTLN, P<0.01; 0.69 of 150 mM glucose, 0.96 of 10% TLN, 0.98 of 1% TLN, P<0.05) were increased, while Drp1 (1.39 of model, 0.96 of HTLN, 1.18 of LTLN, P<0.01; 1.70 of 150 mM glucose, 1.20 of 10% TLN, 1.10 of 1% TLN, P<0.05), phosphorylated Drp1 (2.61 of model, 1.44 of HTLN, P<0.05; 2.80 of 150 mM glucose, 1.50 of 10% TLN, 1.30 of 1% TLN, P<0.01), and Drp1 located in mitochondria (1.80 of 150 mM glucose, 1.00 of 10% TLN, P<0.05) were decreased after treatment with TLN. Additionally, TLN improved schwannopathy by increasing MBP (0.50 of model, 1.05 of HTLN, 0.94 of HTLN, P<0.01; 0.60 of 150 mM glucose, 0.78 of 10% TLN, P<0.01, 0.72 of 1% TLN, P<0.05), Sox101 (0.41 of model, 0.99 of LTLN, P<0.01; 0.48 of 150 mM glucose, 0.65 of 10% TLN, P<0.05, 0.69 of 1% TLN, P<0.01), and MPZ (0.48 of model, 0.66 of HTLN, 0.55 of HTLN, P<0.01; 0.60 of 150 mM glucose, 0.78 of 10% TLN, P<0.01, 0.75 of 1% TLN, P<0.05) expressions. In conclusion, our study indicated that TLN’s function on DPN may link to the improvement of the mitochondrial dynamics, which provides scientific evidence for the clinical application.


2016 ◽  
Vol 11 (1) ◽  
pp. 156 ◽  
Author(s):  
Fei-yong Jia ◽  
Han-yu Dong ◽  
Xin-mei Jiang ◽  
Chun-bo Niu ◽  
Lin Du ◽  
...  

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