This study investigated the effect of Lianmei Qiwu Decoction(LMQWD) on the improvement of cardiac autonomic nerve remodeling in the diabetic rat model induced by the high-fat diet and explored the underlying mechanism of LMQWD through the AMP-activated protein kinase(AMPK)/tropomyosin receptor kinase A(TrkA)/transient receptor potential melastatin 7(TRPM7) signaling pathway. The diabetic rats were randomly divided into a model group, an LMQWD group, an AMPK agonist group, an unloaded TRPM7 adenovirus group(TRPM7-N), an overexpressed TRPM7 adenovirus group(TRPM7), an LMQWD + unloaded TRPM7 adenovirus group(LMQWD+TRPM7-N), an LMQWD + overexpressed TRPM7 adenovirus group(LMQWD+TRPM7), and a TRPM7 channel inhibitor group(TRPM7 inhibitor). After four weeks of treatment, programmed electrical stimulation(PES) was employed to detect the arrhythmia susceptibility of rats. The myocardial cell structure and myocardial tissue fibrosis of myocardial and ganglion samples in diabetic rats were observed by hematoxylin-eosin(HE) staining and Masson staining. The immunohistochemistry, immunofluorescence, real-time quantitative polymerase chain reaction(RT-PCR), and Western blot were adopted to detect the distribution and expression of TRPM7, tyrosine hydroxylase(TH), choline acetyltransferase(ChAT), growth associated protein-43(GAP-43), nerve growth factor(NGF), p-AMPK/AMPK, and other genes and related neural markers. The results showed that LMQWD could significantly reduce the arrhythmia susceptibility and the degree of fibrosis in myocardial tissues, decrease the levels of TH, ChAT, and GAP-43 in the myocardium and ganglion, increase NGF, inhibit the expression of TRPM7, and up-regulate p-AMPK/AMPK and p-TrkA/TrkA levels. This study indicated that LMQWD could attenuate cardiac autonomic nerve remodeling in the diabetic state, and its mechanism was associated with the activation of AMPK, further phosphorylation of TrkA, and inhibition of TRPM7 expression.
Rats ; Animals ; AMP-Activated Protein Kinases/metabolism* ; Nerve Growth Factor/metabolism* ; Diabetes Mellitus, Experimental/drug therapy* ; TRPM Cation Channels/metabolism* ; GAP-43 Protein/metabolism* ; Signal Transduction ; Diabetic Neuropathies/genetics* ; Fibrosis

As one of the most frequent complications of diabetes, diabetic neuropathy often involves peripheral and central nervous systems. Neuroinflammation is the key pathogenic factor of secondary nerve injury in diabetes. NOD-like receptor pyrin domain-containing 3(NLRP3) inflammasome is a group of subcellular multiprotein complexes, including NLRP3, apoptosis associated speck-like protein(ASC), and pro-cysteinyl aspartate specific proteinase 1(pro-caspase-1). NLRP3 inflammasome is an inducer of innate immune responses. Its activation stimulates the inflammatory cascade reaction, promotes the release of inflammatory mediators, triggers cell death and uncontrolled autophagy, activates glial cells, facilitates peripheral immune cell infiltration, and initiates amyoid β(Aβ)-tau cascade reactions. As a result, it contributes to the central nerve, somatic nerve, autonomic nerve, and retinal nerve cell damage secondary to diabetes. Therefore, due to its key role in the neuroinflammation responses of the body, NLRP3 inflammasome may provide new targets for the treatment of diabetic neuropathy. With multi-target and low-toxicity advantages, traditional Chinese medicine plays a vital role in the treatment of diabetic neuropathy. Accumulating evidence has shown that traditional Chinese medicine exerts curative effects on diabetic neuropathy possibly through regulating NLRP3 inflammasome. Although the role of NLRP3 inflammasome in diabetes and related complications has been investigated in the literature, systematical studies on drugs and mechanism analysis for secondary neuropathy are still lacking. In this article, the role of NLRP3 inflammasome in diabetic neuropathy was explored, and the research progress on traditional Chinese medicine in the treatment of diabetic neuropathy through NLRP3 inflammasome was reviewed.
Humans ; Inflammasomes/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Diabetic Neuropathies/drug therapy* ; Medicine, Chinese Traditional ; Neuroinflammatory Diseases ; Inflammation ; Diabetes Mellitus

Diabetic neuropathic pain (DNP) is the most common disabling complication of diabetes. Emerging evidence has linked the pathogenesis of DNP to the aberrant sprouting of sensory axons into the epidermal area; however, the underlying molecular events remain poorly understood. Here we found that an axon guidance molecule, Netrin-3 (Ntn-3), was expressed in the sensory neurons of mouse dorsal root ganglia (DRGs), and downregulation of Ntn-3 expression was highly correlated with the severity of DNP in a diabetic mouse model. Genetic ablation of Ntn-3 increased the intra-epidermal sprouting of sensory axons and worsened the DNP in diabetic mice. In contrast, the elevation of Ntn-3 levels in DRGs significantly inhibited the intra-epidermal axon sprouting and alleviated DNP in diabetic mice. In conclusion, our studies identified Ntn-3 as an important regulator of DNP pathogenesis by gating the aberrant sprouting of sensory axons, indicating that Ntn-3 is a potential druggable target for DNP treatment.
Mice ; Animals ; Diabetes Mellitus, Experimental/metabolism* ; Axons/physiology* ; Diabetic Neuropathies ; Sensory Receptor Cells/metabolism* ; Neuralgia/metabolism*

Neuropathic pain is one of the common complications of diabetes. Tetrahydropalmatine(THP) is a main active component of Corydalis Rhizoma with excellent anti-inflammatory and pain-alleviating properties. This study aims to investigate the therapeutic effect of THP on diabetic neuropathic pain(DNP) and the underlying mechanism. High-fat and high-sugar diet(4 weeks) and streptozotocin(STZ, 35 mg·kg~(-1), single intraperitoneal injection) were employed to induce type-2 DNP in rats. Moreover, lipopolysaccharide(LPS) was used to induce the activation of BV2 microglia in vitro to establish an inflammatory cellular model. Fasting blood glucose(FBG) was measured by a blood glucose meter. Mechanical withdrawal threshold(MWT) was assessed with von Frey filaments, and thermal withdrawal latency(TWL) with hot plate apparatus. The protein expression levels of OX42, inducible nitric oxide synthase(iNOS), CD206, p38, and p-p38 were determined by Western blot, the fluorescence expression levels of OX42 and p-p38 in the dorsal horn of the rat spinal cord by immunofluorescence, the mRNA content of p38 and OX42 in rat spinal cord tissue by qRT-PCR, and levels of nitric oxide(NO), interleukin-1β(IL-1β), interleukin-6(IL-6), tumor necrosis factor-α(TNF-α), interleukin-10(IL-10), and serum fasting insulin(FINS) by enzyme-linked immunosorbent assay(ELISA). RESULTS:: showed that the mo-del group demonstrated significant decrease in MWT and TWL, with pain symptoms. THP significantly improved the MWT and TWL of DNP rats, inhibited the activation of microglia and p38 MAPK signaling pathway in rat spinal cord, and ameliorated its inflammatory response. Meanwhile, THP promoted the change of LPS-induced BV2 microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, suppressed the activation of the p38 MAPK signaling pathway, decreased the expression levels of inflammatory factors NO, IL-1β, IL-6, and TNF-α, and increased the expression level of anti-inflammatory factor IL-10. The findings suggested that THP can significantly ameliorate the pain symptoms of DNP rats possibly by inhibiting the inflammatory response caused by M1 polarization of microglia via the p38 MAPK pathway.
Animals ; Berberine Alkaloids ; Blood Glucose/metabolism* ; Diabetes Mellitus ; Diabetic Neuropathies/genetics* ; Interleukin-10 ; Interleukin-6/metabolism* ; Lipopolysaccharides/pharmacology* ; Microglia ; Neuralgia/metabolism* ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Spinal Cord/metabolism* ; Streptozocin/therapeutic use* ; Tumor Necrosis Factor-alpha/metabolism* ; p38 Mitogen-Activated Protein Kinases/metabolism*

The influence of β-cell function on cardiovascular autonomic neuropathy (CAN), an important diabetes-related complication, is still unclear. In this study, we aimed to investigate the association between residual β-cell function and CAN in patients newly diagnosed with type 2 diabetes. We enrolled 90 newly-diagnosed type 2 diabetic patients and 37 participants with normal glucose tolerance as controls. The patients were divided into a CAN+ group (diabetic patients with CAN, n = 20) and a CAN- group (diabetic patients without CAN, n = 70) according to the standard Ewing battery of tests. Fasting and postprandial plasma glucose, insulin, and C-peptide were measured. Homeostasis model assessment-beta cells (HOMA-B) and HOMA-insulin resistance (IR) were calculated. The prevalence of CAN in this population was 22.2%. Compared with the CAN- group, the CAN+ group had significantly lower fasting plasma insulin (6.60 ± 4.39 vs 10.45 ± 7.82 μ/L, P = 0.029), fasting C-peptide (0.51 ± 0.20 vs 0.82 ± 0.51 nmol/L, P = 0.004), and HOMA-B (21.44 ± 17.06 vs 44.17 ± 38.49, P = 0.002). Fasting C-peptide was correlated with the Valsalva ratio (r = 0.24, P = 0.043) and the 30:15 test (r = 0.26, P = 0.023). Further analysis showed that fasting C-peptide (OR: 0.041, 95% CI 0.003-0.501, P = 0.012) and HOMA-B (OR: 0.965, 95% CI 0.934-0.996, P = 0.028) were independently associated with cardiovascular autonomic nerve function in this population. The patients with fasting C-peptide values < 0.67 nmol/L were more likely to have CAN than those with C-peptide levels ≥0.67 nmol/L (OR: 6.00, 95% CI 1.815-19.830, P = 0.003). A high prevalence of CAN was found in patients with newly-diagnosed type 2 diabetes. Decreased β-cell function was closely associated with CAN in this population.
Adult ; Asian Continental Ancestry Group ; Blood Glucose ; analysis ; Diabetes Mellitus, Type 2 ; complications ; metabolism ; Diabetic Neuropathies ; etiology ; Fasting ; physiology ; Female ; Glucose ; metabolism ; Humans ; Insulin ; metabolism ; Insulin Resistance ; physiology ; Insulin-Secreting Cells ; metabolism ; Male ; Middle Aged

Diabetic peripheral neuropathy (DPN) is a progressive neurodegenerative disease of peripheral nervous system with high energy requirement. The adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor- γ coactivator 1 α (PGC-1 α) axis plays a key role in regulating mitochondrial energy metabolism. Increasing preclinical evidences have shown that inhibition of AMPK/PGC-1 α pathway leading to mitochondrial dysfunction in neurons or Schwann cells contributes to neuron apoptosis, distal axonopathy and nerve demyelination in DPN. Some Chinese medicine formulae or extracts from herbs may have potential neuroprotective effects on DPN via activating AMPK/PGC-1 α pathway and improving mitochondrial function.
AMP-Activated Protein Kinases ; metabolism ; Diabetic Neuropathies ; drug therapy ; pathology ; Humans ; Medicine, Chinese Traditional ; Mitochondria ; metabolism ; pathology ; Neuroprotective Agents ; therapeutic use ; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha ; metabolism ; Signal Transduction

To explore the role of vascular endothelial growth factor (VEGF) in diabetic peripheral neuropathic pain in rats.
 Methods: Twenty-four adult male Sprague-Dawley rats aged 8 weeks were randomly divided into 3 groups (n=8 per group). The control group (C group): rats were intraperitoneally injected with sodium citrate solution at 10 mL/kg; the model group (M group): rats were intraperitoneally injected with streptozotocin at 65 mg/kg; the treatment group (T group): rats received intraperitoneal injection of anti-VEGF antibody (10 mg/kg) at the 1st, 3rd, 7th, 10th day after STZ treatment. Meanwhile, rats of C and M group were received with the same volume of sodium citrate solution. Blood glucose was measured before 1 day or at the 1st, 3rd, 7th or 14th day after receiving STZ. Body weight, paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured before 1 day or at the 1st, 3rd, 5th, 7th, 10th or 14th day after receiving STZ. All lumbar spinal cords were dissected to examine the p-protein kinase B (p-Akt) and transient receptor potential vanilloid 1 (TRPV1) expression by Western blot.
 Results: After injection with STZ, the body weight showed significant differences at some time point between the M, T or C group (P<0.01); body weight of rat in the C group were increased gradually. Compared with the C group, the fast blood glucose in the M or the T Group at the same time points were increased significantly (P<0.01). The PWMT and PWTL of the M, T or C group were significant difference among various time points (P<0.01). The PWMT and PWTL in the M or T group were obviously reduced compared with those in the C group (P<0.01). Compared with the M group, the PWMT and PWTL in the T group were increased at the 10th or 14th day (P<0.01 or P<0.05). Compared with the C group, the p-Akt and TRPV1 levels in the M and T group were increased (P<0.01). Compared with the M group, p-Akt and TRPV1 levels in T group were decreased (P<0.01).
 Conclusion: VEGF is able to regulate the expression of TRPV1 through PI3K/Akt pathway, which contributes to diabetic peripheral neuropathic pain in rats. Anti-VEGF treatment may be useful for alleviation of diabetic peripheral neuropathic pain.
Animals ; Antibodies ; pharmacology ; therapeutic use ; Diabetes Mellitus, Experimental ; chemically induced ; Diabetic Neuropathies ; chemically induced ; drug therapy ; Gene Expression Regulation ; drug effects ; Male ; Phosphatidylinositol 3-Kinases ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; TRPV Cation Channels ; genetics ; Vascular Endothelial Growth Factor A ; metabolism

OBJECTIVETo observe the deregulation of autophagy in diabetic peripheral neuropathy (DPN) and investigate whether Jinmaitong ( JMT) alleviates DPN by inducing autophagy.

METHODSDPN models were established by streptozotocin-induced diabetic rats and Schwann cells (SCs) cultured in high glucose medium. The pathological morphology was observed by the improved Bielschowsky's nerve fiber axonal staining and the Luxol fast blue-neutral red myelin staining. The ultrastructure was observed by the transmission electron microscopy. Beclin1 level was detected by immunohistochemistry and Western blot. The proliferation of cultured SCs was detected by methylthiazolyldiphenyl-tetrazolium bromide.

RESULTSDiabetic peripheral nerve tissues demonstrated pathological morphology and reduced autophagic structure, accompanied with down-regulation of Beclin1. JMT apparently alleviated the pathological morphology change and increased the autophagy [in vivo, Beclin1 integral optical density (IOD) value of the control group 86.6±17.7, DM 43.9±8.8, JMT 73.3 ±17.8, P<0.01 or P<0.05, in vitro Beclin1 IOD value of the glucose group 0.47±0.25 vs the control group 0.88±0.29, P<0.05]. Consequently, inhibition of autophagy by 3-methyladenine resulted in a time- and concentration-dependent decrease of the proliferation of SCs (P<0.05, P<0.01).

CONCLUSIONSDown-regulation of autophagy in SCs might contribute to the pathogenesis of DPN. JMT alleviates diabetic peripheral nerve injury at least in part by inducing autophagy.

Animals ; Autophagy ; drug effects ; Axons ; drug effects ; pathology ; Beclin-1 ; metabolism ; Cell Proliferation ; drug effects ; Cells, Cultured ; Diabetes Mellitus, Experimental ; complications ; drug therapy ; pathology ; Diabetic Neuropathies ; complications ; drug therapy ; pathology ; Down-Regulation ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Glucose ; pharmacology ; Immunohistochemistry ; Male ; Rats, Wistar ; Schwann Cells ; drug effects ; pathology ; Sciatic Nerve ; drug effects ; pathology ; ultrastructure ; Staining and Labeling

Huanglian Wendan decoction (HLWDD) has been used for the treatment of symptom of "Re", one of major causes in diabetes and metabolic disorders, according to the theory of traditional Chinese medicine. The present study aimed at investigating the cerebral protective effects of HLWDD on diabetic encephalopathy (DE), one of the major diabetic complications. The effects of HLWDD and metformin were analyzed in the streptozocin (STZ) + high-glucose-fat (HGF) diet-induced DE rats by gastric intubation. In the present study, the effects of HLWDD on cognition deficits were investigated after 30-day intervention at two daily dose levels (3 and 6 g·kg). To explore the potential mechanisms underlying the effects of HLWDD, we detected the alterations of neuronal damages, inflammatory cytokines, and impaired insulin signaling pathway in hippocampus of the DE rats. Based on our results from the present study, we concluded that the protective effects of HLWDD against the cognitive deficits and neuronal damages through inhibiting the release of inflammatory cytokines and repairing insulin signaling pathway in hippocampus of the DE rats.
Animals ; Cognition Disorders ; genetics ; metabolism ; prevention & control ; Cytokines ; genetics ; metabolism ; Diabetic Neuropathies ; drug therapy ; genetics ; metabolism ; psychology ; Drugs, Chinese Herbal ; administration & dosage ; Hippocampus ; drug effects ; metabolism ; Humans ; Insulin ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley

Along with the development of economy and society, type 2 diabetic mellitus (T2DM) has become one of the most common diseases at the global level. As one of the complications of T2DM, diabetic neuropathic pain (DNP) stubbornly and chronically affects the health and life of human beings. In the pain field, dorsal root ganglion (DRG) is generally considered as the first stage of the sensory pathway where the hyperexcitability of injured neurons is associated with different kinds of peripheral neuropathic pains. The abnormal electrophysiology is mainly due to the changed properties of voltage-gated sodium channels (VGSCs) and the increased sodium currents (I(Na)). Curcumin is an active ingredient extracted from turmeric and has been demonstrated to ameliorate T2DM and its various complications including DNP effectively. The present study demonstrates that the I(Na) of small-sized DRG neurons are significantly increased with the abnormal electrophysiological characteristics of VGSCs in type 2 diabetic neuropathic pain rats. And these abnormalities can be ameliorated efficaciously by a period of treatment with curcumin.
Animals ; Curcumin ; pharmacology ; Diabetes Mellitus, Experimental ; complications ; Diabetes Mellitus, Type 2 ; complications ; Diabetic Neuropathies ; drug therapy ; Ganglia, Spinal ; cytology ; drug effects ; metabolism ; Neuralgia ; drug therapy ; Neurons ; drug effects ; metabolism ; Rats ; Sodium ; Voltage-Gated Sodium Channels ; physiology