Painful diabetic neuropathy (PDN) is a diabetes mellitus complication. Unfortunately, the mechanisms underlying PDN are still poorly understood. Adenosine triphosphate (ATP)-gated P2X7 receptor (P2X7R) plays a pivotal role in non-diabetic neuropathic pain, but little is known about its effects on streptozotocin (STZ)-induced peripheral neuropathy. Here, we explored whether spinal cord P2X7R was correlated with the generation of mechanical allodynia (MA) in STZ-induced type 1 diabetic neuropathy in mice. MA was assessed by measuring paw withdrawal thresholds and western blotting. Immunohistochemistry was applied to analyze the protein expression levels and localization of P2X7R. STZ-induced mice expressed increased P2X7R in the dorsal horn of the lumbar spinal cord during MA. Mice injected intrathecally with a selective antagonist of P2X7R and P2X7R knockout (KO) mice both presented attenuated progression of MA. Double-immunofluorescent labeling demonstrated that P2X7R-positive cells were mostly co-expressed with Iba1 (a microglia marker). Our results suggest that P2X7R plays an important role in the development of MA and could be used as a cellular target for treating PDN.
Acetamides/pharmacology* ; Animals ; Diabetes Mellitus, Experimental/complications* ; Diabetes Mellitus, Type 1/complications* ; Diabetic Neuropathies/etiology* ; Hyperalgesia/etiology* ; Male ; Mice ; Mice, Inbred C57BL ; Quinolines/pharmacology* ; Receptors, Purinergic P2X7/physiology* ; Spinal Cord/physiology* ; Streptozocin/pharmacology*

Patients with diabetic peripheral neuropathy experience debilitating pain that significantly affects their quality of life (Abbott et al., 2011), by causing sleeping disorders, anxiety, and depression (Dermanovic Dobrota et al., 2014). The primary clinical manifestation of painful diabetic neuropathy (PDN) is mechanical hypersensitivity, also known as mechanical allodynia (MA) (Callaghan et al., 2012). MA's underlying mechanism remains poorly understood, and so far, based on symptomatic treatment, it has no effective therapy (Moore et al., 2014).
Animals ; CX3C Chemokine Receptor 1/physiology* ; Chemokine CX3CL1/physiology* ; Diabetes Mellitus, Experimental/complications* ; Diabetes Mellitus, Type 1/complications* ; Diabetic Neuropathies/etiology* ; Hyperalgesia/etiology* ; Mice ; Mice, Inbred C57BL ; Spinal Cord/physiology* ; Streptozocin/pharmacology*

Objective To investigate the effects of simvastatin on diabetic neuropathic pain and systematic inflammation in diabetic rats and explore their molecular mechanisms.Methods Totally 24 rats were equally randomized into the normal+vehicle(NV)group,diabetic+vehicle(DV)group,and diabetic+simvastatin(DS)group using the random number table.Streptozotocin(STZ)was used to establish the rat models of diabetes.Blood glucose,body mass,paw withdrawal mechanical threshold(PWMT),and paw withdrawal thermal latency(PWTL)in each group were observed on days 7,14,21,and 28 after STZ injection.On day 28 after STZ injection,rats were sacrificed,and the lumbar spinal dorsal horn and serum were collected.Western blotting was used to detect the expression of receptor for advanced glycation end products(RAGE)and the phosphorylation levels of protein kinase B(AKT),extracellular signal-regulated kinase(ERK),p38,and c-Jun N-terminal kinase(JNK)in the spinal dorsal horn of rats in each group.Enzyme-linked immunosorbent assay was performed to determine the serum concentrations of oxidized low density lipoprotein(ox-LDL)and interleukin-1β(IL-1β).Results On days 14,21 and 28 after STZ injection,the PWMT in DV group were(8.6 ± 0.8),(7.1 ± 1.6),and(7.8 ± 0.8)g respectively,which were significantly lower than (12.0 ± 0.9)(=8.482, =0.000),(11.6 ± 1.5)(=11.309, =0.000),and(11.7 ± 1.5)g(=9.801, =0.000)in NV group.The PWMT in DS group on days 21 and 28 were(9.4 ± 1.4)(=5.780, =0.000)and(9.7 ± 0.9)g(=4.775, =0.003),respectively,which were significantly improved comparing with those of DV group.On days 7,14,21,and 28,there were no significant differences in PWTL among these three groups (all <0.05).The expression of RAGE in the spinal dorsal horn of DV group was significantly higher than those of NV group(=6.299, =0.000)and DS group(=2.891, =0.025).The phosphorylation level of AKT in the spinal dorsal horn of DV group was significantly higher than those of NV group(=8.915,=0.000)and DS group(=4.103,=0.003).The phosphorylation levels of ERK( =8.313,=0.000),p38( =2.965, =0.022),and JNK(=7.459, =0.000)in the spinal dorsal horn of DV group were significantly higher than those of NV group;the phosphorylation level of JNK in the spinal dorsal horn of DS group was significant lower than that of DV group(=3.866, =0.004);however,there were no significant differences in the phosphorylation levels of ERK(=1.987,=0.122)and p38(=1.260,=0.375)in the spinal dorsal horn between DS group and DV group.The serum concentrations of ox-LDL and IL-1β in DV group were(41.86 ± 13.40)ng/ml and(108.16 ± 25.88)pg/ml,respectively,which were significantly higher than those in NV group [(24.66 ± 7.87)ng/ml(=3.606,=0.003)and(49.32 ± 28.35)pg/ml(=5.079,=0.000)] and DS group [(18.81 ± 5.62)ng/ml (=4.833, =0.000)and(32.73 ± 11.73)pg/ml(=6.510, =0.000)].Conclusions Simvastatin can relieve the mechanical allodynia of diabetic rats possibly by inhibiting the activation of RAGE/AKT and the phosphorylation of JNK in the spinal dorsal horn.Simvastatin can also decrease the serum concentrations of ox-LDL and IL-1β in diabetic rats,which may contribute to the relief of systematic inflammation.
Animals ; Diabetes Mellitus, Experimental ; complications ; Hyperalgesia ; Inflammation ; drug therapy ; Interleukin-1beta ; blood ; Lipoproteins, LDL ; blood ; Neuralgia ; drug therapy ; Proto-Oncogene Proteins c-akt ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptor for Advanced Glycation End Products ; metabolism ; Simvastatin ; pharmacology

OBJECTIVE: To observe the effects of AdipoRon orally on the functions of spleen and pancreas in type 2 diabetic mice, in order to present data for clinical application. METHODS: Forty C57/BL6 male mice were randomly divided into 2 groups: normal control group (n=10) and model group (n=30), the former group was fed normally, while the later group was fed with high fat and sugar for 4 weeks.After that, type 2 diabetes model was established in DM group induced by intraperitoneal injection of streptozotocin (STZ, 40 mg/kg).As type 2 diabetes model established successfully, the model mice were randomly divided into three groups (n=10): diabetes mellitus (DM) group, high dose of AdipoRon group (DM + H) and low dose of adiponRon group (DM + L).All the four groups were treated with saline, saline, AdipoRon at the doses of 20 mg/kg and 50 mg/kg by gavages respectively, once a day for 10 days.And then put them to death for collecting blood, pancreas and spleen.Pathological changes of pancreas were observed with a light microscope after HE staining.Protein contents of insulin receptor (INSR), insulin receptor substrate 1( IRS-1) and tumor necrosis factor-α(TNF-α) in pancreatic and spleen tissues were detected by ELISA.The protein level of phosphorylation insulin receptor substrate 1(p-IRS-1) in pancreas was determined by Western blot, and the expression of insulin mRNA in pancreas was tested by RT-PCR. RESULTS: Under the light microscope, it was visible that the pancreatic tissue in NC group was full and closely packed, and the islet was big.Pancreatic tissue of DM mice was incompact and the islet of DM mice was smaller than that of normal mice.As for the mice treated with AdipoRon orally, the pancreatic tissue was full and closely arranged, and the islet was slightly smaller.Compared with NC group, the levels of TNF-α in pancreas and spleen of DM group were increased markedly, the levels of INSR and IRS-1 were decreased, the spleen coefficient, p-IR-1 protein level and insulin mRNA expression in pancreas were decreased, all were significant statistically (P＜0.05).Compared with DM group, the levels of TNF-α in pancreas and spleen of AdipoRon groups were decreased, the levels of INSR and IRS-1 in pancreas and spleen of AdipoRon groups were increased, while the spleen coefficient was increased (P＜0.05).The p-IRS-1 protein level and insulin mRNA expression in pancreas in DM+H group were increased (P＜0.05).Compared with DM + L group, the level of TNF-α was decreased, and the levels of INSR and IRS-1 were significantly increased (P＜0.05) in DM + H group (P＜0.05). CONCLUSION Oral administration of AdipoRon can protect the spleen and pancreas of diabetic mice by decreasing the inflammatory response, up-regulating the expression of INSR, and increasing p-IRS-1 level in diabetic mice.
Animals ; Diabetes Mellitus, Experimental ; Diabetes Mellitus, Type 2 ; complications ; drug therapy ; Inflammation ; Insulin ; Insulin Receptor Substrate Proteins ; drug effects ; Male ; Mice ; Pancreas ; Piperidines ; pharmacology ; Random Allocation ; Receptor, Insulin ; drug effects ; Spleen ; drug effects

Insulin-like growth factor-1 receptor (IGF-1R) is involved in both glucose and bone metabolism. IGF-1R signaling regulates the canonical Wnt/β-catenin signaling pathway. In this study, we investigated whether the IGF-1R/ β-catenin signaling axis plays a role in the pathogenesis of diabetic osteoporosis (DOP). Serum from patients with or without DOP was collected to measure the IGF-1R level using enzyme-linked immunosorbent assay (ELISA). Rats were given streptozotocin following a four-week high-fat diet induction (DOP group), or received vehicle after the same period of a normal diet (control group). Dual energy X-ray absorption, a biomechanics test, and hematoxylin-eosin (HE) staining were performed to evaluate bone mass, bone strength, and histomorphology, respectively, in vertebrae. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to measure the total and phosphorylation levels of IGF-1R, glycogen synthase kinase-3β (GSK-3β), and β-catenin. The serum IGF-1R level was much higher in patients with DOP than in controls. DOP rats exhibited strikingly reduced bone mass and attenuated compression strength of the vertebrae compared with the control group. HE staining showed that the histomorphology of DOP vertebrae was seriously impaired, which manifested as decreased and thinned trabeculae and increased lipid droplets within trabeculae. PCR analysis demonstrated that IGF-1R mRNA expression was significantly up-regulated, and western blotting detection showed that phosphorylation levels of IGF-1R, GSK-3β, and β-catenin were enhanced in DOP rat vertebrae. Our results suggest that the IGF-1R/β-catenin signaling axis plays a role in the pathogenesis of DOP. This may contribute to development of the underlying therapeutic target for DOP.
Aged ; Animals ; Bone Density ; Diabetes Mellitus, Experimental/complications* ; Diabetes Mellitus, Type 2/complications* ; Female ; Humans ; Male ; Middle Aged ; Osteoporosis/etiology* ; Rats ; Receptor, IGF Type 1/physiology* ; Signal Transduction ; Streptozocin ; beta Catenin/physiology*

Diabetic cardiomyopathy( DCM) is one of the major cardiovascular complications of diabetes mellitus. Based on the clinical efficacy of Danzhi Jiangtang Capsules( DJC) in the prevention and treatment of diabetes and its cardiovascular complications,both in vivo and in vitro methods were adopted to investigate its effect and underlying mechanism of protecting myocardial injury induced by diabetes. The type 2 diabetic rats were prepared by feeding high-energy food combined with streptozotin( STZ) injection,and the effects of DJC were observed by blood sugar,blood lipid,hemodynamic index,cardiac weight index and the change of cardiac pathological morphology. The protein expressions of TLR4,MyD88 and NF-κB p65 in myocardial tissue were detected and the possible mechanism was preliminarily analyzed. Besides this,DJC containing serum was prepared,H9 c2 cardiomyocyte induced by high sugar were studied to investigate the mechanism of TLR4/MyD88/NF-κB signaling pathway regulating cardiomyocyte injury and the therapeutic effect of DJC. The results demonstrated that fasting blood sugar,glycosylated hemoglobin,total cholesterol and glycerol triglyceride were significantly reduced( P<0. 01,P<0. 05). Cardiac weight index,left ventricle weight index,LVEDP and the protein expressions of TLR4,MyD88 and NF-κB p65 were significantly reduced( P<0. 01,P<0. 05). LVSP,+dp/dtmaxand-dp/dtmaxincreased significantly( P<0. 01,P< 0. 05). Moreover,the pathological damage of myocardial tissue in rats improved significantly. Meanwhile,the protein expressions of TLR4,MyD88 and NF-κB p65 in cardiomyocytes induced by high sugar were significantly inhibited( P<0. 01).It showed that DJC were effective in preventing and treating myocardial injury induced by diabetes and its mechanism may be related to the over-expression of TLR4/MyD88/NF-κB signaling pathway induced by high sugar.
Animals ; Blood Glucose ; Capsules ; Diabetes Mellitus, Experimental/complications* ; Diabetic Cardiomyopathies/drug therapy* ; Drugs, Chinese Herbal/therapeutic use* ; Myeloid Differentiation Factor 88/metabolism* ; NF-kappa B/metabolism* ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Toll-Like Receptor 4/metabolism*

Calpain activation contributes to hyperglycemia-induced endothelial dysfunction and apoptosis. This study was designed to investigate the role of calpain inhibition in improving diabetic erectile dysfunction (ED) in mice. Thirty-eight-week-old male C57BL/6J mice were divided into three groups: (1) nondiabetic control group, (2) diabetic mice + vehicle group, and (3) diabetic mice + MDL28170 (an inhibitor of calpain) group. Type 1 diabetes was induced by intraperitoneal injection of streptozotocin at 60 mg kg^-1 body weight for 5 consecutive days. Thirteen weeks later, diabetic mice were treated with MDL28170 or vehicle for 4 weeks. The erectile function was assessed by electrical stimulation of the cavernous nerve. Penile tissues were collected for measurement of calpain activity and the endothelial nitric oxide synthase (eNOS)-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway. Terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling (TUNEL) staining was used to evaluate apoptosis. Caspase-3 expression and activity were also measured to determine apoptosis. Our results showed that erectile function was enhanced by MDL28170 treatment in diabetic mice compared with the vehicle diabetic group. No differences in calpain-1 and calpain-2 expressions were observed among the three groups. However, calpain activity was increased in the diabetic group and reduced by MDL28170. The eNOS-NO-cGMP pathway was upregulated by MDL28170 treatment in diabetic mice. Additionally, MDL28170 could attenuate apoptosis and increase the endothelium and smooth muscle levels in corpus cavernosum. Inhibition of calpain could improve erectile function, probably by upregulating the eNOS-NO-cGMP pathway and reducing apoptosis.
Animals ; Apoptosis/drug effects* ; Calpain/antagonists & inhibitors* ; Cyclic GMP/biosynthesis* ; Diabetes Complications/drug therapy* ; Diabetes Mellitus, Experimental/complications* ; Dipeptides/therapeutic use* ; Endothelium/metabolism* ; Enzyme Inhibitors/therapeutic use* ; Erectile Dysfunction/etiology* ; In Situ Nick-End Labeling ; Male ; Mice ; Mice, Inbred C57BL ; Muscle, Smooth/metabolism* ; Nitric Oxide Synthase Type III/biosynthesis* ; Penis/enzymology* ; Up-Regulation

The study aimed to investigate the intervening role of Didang decoction (DDD) at different times in macrovascular endothelial defense function, focusing on its effects on the AMP-activated protein kinase (AMPK) signaling pathway. The effects of DDD on mitochondrial energy metabolism were also investigated in rat aortic endothelial cells (RAECs). Type 2 diabetes were induced in rats by streptozotocin (STZ) combined with high fat diet. Rats were randomly divided into non-intervention group, metformin group, simvastatin group, and early-, middle-, late-stage DDD groups. Normal rats were used as control. All the rats received 12 weeks of intervention or control treatment. Western blots were used to detect the expression of AMP-activated protein kinase α1 (AMPKα1) and peroxisome proliferator-activated receptor 1α (PGC-1α). Changes in the intracellular AMP and ATP levels were detected with ELISA. Real-time-PCR was used to detect the mRNA level of caspase-3, endothelial nitric oxide synthase (eNOS), and Bcl-2. Compared to the diabetic non-intervention group, a significant increase in the expression of AMPKα1 and PGC-1α were observed in the early-stage, middle-stage DDD groups and simvastatin group (P < 0.05). The levels of Bcl-2, eNOS, and ATP were significantly increased (P < 0.05), while the level of AMP and caspase-3 were decreased (P < 0.05) in the early-stage DDD group and simvastatin group. Early intervention with DDD enhances mitochondrial energy metabolism by regulating the AMPK signaling pathway and therefore may play a role in strengthening the defense function of large vascular endothelial cells and postpone the development of macrovascular diseases in diabetes.
AMP-Activated Protein Kinases ; metabolism ; Adenosine Triphosphate ; metabolism ; Animals ; Aorta ; drug effects ; metabolism ; Cardiovascular Diseases ; metabolism ; prevention & control ; Caspase 3 ; metabolism ; Diabetes Mellitus, Experimental ; complications ; drug therapy ; metabolism ; Diabetes Mellitus, Type 2 ; complications ; drug therapy ; metabolism ; Diptera ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Endothelial Cells ; drug effects ; metabolism ; Endothelium, Vascular ; drug effects ; metabolism ; Energy Metabolism ; drug effects ; Leeches ; Mitochondria ; drug effects ; metabolism ; Nitric Oxide Synthase Type III ; metabolism ; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha ; metabolism ; Phytotherapy ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Prunus persica ; Rats, Sprague-Dawley ; Rheum ; Signal Transduction

OBJECTIVETo investigate the effect of Xuezhikang (, XZK) on renal cell apoptosis in diabetic rats and the possible mechanism.

METHODSSixty-six rats were randomly divided into 3 groups: the normal, model and XZK groups. In each group, the rats were further randomly divided into 3-month and 6-month subgroups, respectively. Diabetes of rats was induced by a single intraperitoneal injection of 1% streptozocin at 60 mg/kg body weight. Rats in the XZK group received gastric perfusion of XZK (1200 mg/kg body weight) everyday for 3 or 6 months, while rats in the normal and model groups received equal volume of saline. Twenty-four hours' urine was collected for urinary albumin excretion (UAE) measurement. Periodic acid-Schiff (PAS) and Masson's trichrome staining were used for saccharides and collagen detection. Cell apoptosis of renal cortex was investigated by TdT-mediated dUTP nick end labeling (TUNEL) staining. Bax and Bcl-2 expressions were detected by immunohistochemistry and Western blot, respectively. Cytochrome C (Cyt C) and caspase-9 concentration were detected by Western blot.

RESULTSCompared with the model group, XZK treatment could significantly decrease the kidney hypertrophy index, 24 h UAE, renal cell apoptosis, cytoplasmic Cyt C level and active caspase-9 level, as well as suppress the increment of Bax and up-regulate the expression of Bcl-2, leading to the suppression of Bax/Bcl-2 ratio at 3 and 6 months (P<0.05 or P<0.01). Moreover, XZK treatment could alleviate the deposition of PAS-stained saccharides and Masson's trichromestained collagen to different extent.

CONCLUSIONSRenal cell apoptosis was observed in diabetic kidney, in which mitochondrial apoptotic pathway might be involved. XZK treatment could attenuate pathological changes in diabetic kidney and reduce renal cell apoptosis, probably via the suppression of Bax/Bcl-2 ratio, which lead to inhibition of Cyt C release and following caspase-9 activation.

Albuminuria ; blood ; complications ; Animals ; Apoptosis ; drug effects ; Blood Glucose ; metabolism ; Caspase 9 ; metabolism ; Cytochromes c ; metabolism ; Diabetes Mellitus, Experimental ; blood ; drug therapy ; metabolism ; pathology ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Hypertrophy ; In Situ Nick-End Labeling ; Kidney ; drug effects ; pathology ; Kidney Glomerulus ; pathology ; Lipids ; blood ; Male ; Mesangial Cells ; drug effects ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats, Sprague-Dawley ; Streptozocin ; bcl-2-Associated X Protein ; 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