Mechanism by which Huoxue Tongluo Qiwei Decoction improves the erectile function of rats with diabetic erectile dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Huoxue Tongluo Qiwei Decoction is a classical herbal formula, which can improve the symptoms of erectile dysfunction (ED) patients and has a good therapeutic effect on patients with diabetic erectile dysfunction (DIED). The main function of Huoxue Tongluo Qiwei Decoction is to stimulate the blood circulation and dredge collaterals, remove blood stasis, and calm wind.

RATIONALE

To further explore the mechanism of Huoxue Tongluo Qiwei Decoction in the treatment of DIED, related animal experiments were designed.

MATERIALS AND METHODS

The chemical constituents of Huoxue Tongluo Qiwei Decoction were identified with the help of high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A rat model was induced by streptozotocin (STZ) and screened by apomorphine (APO). Serum sE-selectin, lysyl oxidase-1 (LOX-1), malondialdehyde (MDA) and other markers of vascular endothelial injury and related indicators of oxidative stress were studied through enzyme-linked immunosorbent assay (ELISA). The endothelial cells and ultrastructure of the corpus cavernosum were examined by electron microscopy and HE staining. The expression of protein and mRNA was detected by western blotting (WB) and real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The results of the study revealed that the sE-selectin, LOX-1, intercellular adhesion molecule-1 (sICAM-1), endothelial microparticles (EMPs), P-selectin (CD62P), and MDA levels in the serum of group M rats were considerably higher than rats of group K, while the superoxide dismutase (SOD) level showed a significant decrease. In addition, the PKC pathway was activated, and the expression of related proteins and mRNA was increased. After 8 weeks of intervention with Huoxue Tongluo Qiwei Decoction and LY333531, serum level of sE-selectin, LOX-1, sICAM-1, EMPs, CD62P and MDA in L, D and G groups were remarkably lower than group M while SOD level increased significantly, protein kinase C (PKC) pathway was inhibited with the improved erectile function of rats.

CONCLUSION

Huoxue Tongluo Qiwei Decoction can inhibit the expression of protein and mRNA of the PKCβ signaling pathway related molecules in DIED rats to cure the injury of vascular endothelial, enhance antioxidant capacity, and prevent the activation of platelet, thus improving erectile function in rats with DIED.

The Biological Role of Nestin(+)-Cells in Physiological and Pathological Cardiovascular Remodeling

The intermediate filament protein nestin was identified in diverse populations of cells implicated in cardiovascular remodeling. Cardiac resident neural progenitor/stem cells constitutively express nestin and following an ischemic insult migrate to the infarct region and participate in angiogenesis and neurogenesis. A modest number of normal adult ventricular fibroblasts express nestin and the intermediate filament protein is upregulated during the progression of reparative and reactive fibrosis. Nestin depletion attenuates cell cycle re-entry suggesting that increased expression of the intermediate filament protein in ventricular fibroblasts may represent an activated phenotype accelerating the biological impact during fibrosis. Nestin immunoreactivity is absent in normal adult rodent ventricular cardiomyocytes. Following ischemic damage, the intermediate filament protein is induced in a modest population of pre-existing adult ventricular cardiomyocytes bordering the peri-infarct/infarct region and nestin⁽⁺⁾-ventricular cardiomyocytes were identified in the infarcted human heart. The appearance of nestin⁽⁺⁾-ventricular cardiomyocytes post-myocardial infarction (MI) recapitulates an embryonic phenotype and depletion of the intermediate filament protein inhibits cell cycle re-entry. Recruitment of the serine/threonine kinase p38 MAPK secondary to an overt inflammatory response after an ischemic insult may represent a seminal event limiting the appearance of nestin⁽⁺⁾-ventricular cardiomyocytes and concomitantly suppressing cell cycle re-entry. Endothelial and vascular smooth muscle cells (VSMCs) express nestin and upregulation of the intermediate filament protein may directly contribute to vascular remodeling. This review will highlight the biological role of nestin⁽⁺⁾-cells during physiological and pathological remodeling of the heart and vasculature and discuss the phenotypic advantage attributed to the intermediate filament protein.

Natural antioxidants in the treatment and prevention of diabetic nephropathy; a potential approach that warrants clinical trials

Diabetic nephropathy is the major cause of end-stage renal disease and effective and new therapeutic approaches are needed in diabetic nephropathy and chronic kidney diseases. Oxidative stress and inflammatory process are important factors contributing to kidney damage by increasing production of oxidants. KEAP1/Nrf2/ARE pathway regulates the transcription of many antioxidant genes and modulation of the pathway up regulates antioxidants. NFB controls the expression of genes involved in the inflammatory response. Natural substances have antioxidant and anti-inflammatory activities and have an impact on NFB and KEAP1/Nrf2/ARE pathways. The preclinical studies explored the effectiveness of whole herbs, plants or seeds and their active ingredients in established diabetic nephropathy. They ameliorate oxidative stress induced kidney damage, enhance antioxidant system, and decrease inflammatory process and fibrosis; most likely by activating KEAP1/Nrf2/ARE pathway and by deactivating NFB pathway. Whole natural products contain balanced antioxidants that might work synergistically to induce beneficial therapeutic outcome. In this context, more clinical studies involving whole plants or herbal products or mixtures of different herbs and plants and their active ingredients might change our strategies for the management of diabetic nephropathy. The natural products might be useful as preventive interventions and studies are required in this field.

Renal damage following Alloxan-induced diabetes is associated with generation of reactive oxygen species, alterations of p53, TGF-β1, and extracellular matrix metalloproteinases in rats

Renal damage is a common problem in diabetes. Alloxan, a potent hyperglycemic and diabetogenic molecule, can induce diabetes through oxidative stress-related mechanisms. Here, we hypothesize that "Alloxan-induced renal damage is associated with alterations of p53, TGF-β1, and extracellular matrix metalloproteinases." To test our hypothesis, we established an animal model (male abino rats) and induced diabetes by intraperitoneal injection of Alloxan monohydrate. Rats with fasting blood glucose level ≥ 200 mg/dL were considered diabetic and were sacrificed after 14, 28, and 42 day intervals. Tissue levels of malondialdehyde and glutathione levels (markers of oxidative stress), and serum MMP-1 were measured. The expression patterns of p53, TGF-β1were evaluated using Western blot and immunohistochemical methods. TIMP-1 expression pattern was determined using RT-PCR and immunohistochemical methods. Alloxan treatment induced histological features of renal damage (inflammation and fibrosis) and was associated with deterioration of the renal functions (elevated blood urea nitrogen and creatinin levels), hyperglycemia, and oxidative stresss (increased malondialdehyde and decreased glutathione levels). There was over-expression of the TGF-β1 protein (profibrogenic protein), p53 (proapoptotic protein), and alterations of extracellular matrix proteins (low level of serum MMP-1 and over-expression of TIMP-1). Alterations of TGF-β, p53, and extracellular matrix metalloproteinases contribute to the pathogenesis of Alloxan-induced renal damage.

Damaging effects of hyperglycemia on cardiovascular function: spotlight on glucose metabolic pathways

The incidence of cardiovascular complications associated with hyperglycemia is a growing global health problem. This review discusses the link between hyperglycemia and cardiovascular diseases onset, focusing on the role of recently emerging downstream mediators, namely, oxidative stress and glucose metabolic pathway perturbations. The role of hyperglycemia-mediated activation of nonoxidative glucose pathways (NOGPs) [i.e., the polyol pathway, hexosamine biosynthetic pathway, advanced glycation end products (AGEs), and protein kinase C] in this process is extensively reviewed. The proposal is made that there is a unique interplay between NOGPs and a downstream convergence of detrimental effects that especially affect cardiac endothelial cells, thereby contributing to contractile dysfunction. In this process the AGE pathway emerges as a crucial mediator of hyperglycemia-mediated detrimental effects. In addition, a vicious metabolic cycle is established whereby hyperglycemia-induced NOGPs further fuel their own activation by generating even more oxidative stress, thereby exacerbating damaging effects on cardiac function. Thus NOGP inhibition, and particularly that of the AGE pathway, emerges as a novel therapeutic intervention for the treatment of cardiovascular complications such as acute myocardial infarction in the presence hyperglycemia.

Ghrelin ameliorates impaired angiogenesis of ischemic myocardium through GHSR1a-mediated AMPK/eNOS signal pathway in diabetic rats

OBJECTIVES

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHSR), has been found to stimulate angiogenesis in vivo and in vitro. However, the effect and the corresponding mechanisms of ghrelin on impaired myocardial angiogenesis in diabetic and myocardial infarction (MI) rat model are still unknown.

METHODS

In the present study, adult SD rats were randomly divided into 4 groups: control, DM, DM+ghrelin, DM+ghrelin+[D-Lys3]-GHRP-6 groups. DM was induced by streptozotocin (STZ) 60 mg/kg body weight. 12 weeks post STZ injection all groups were subjected to MI, which was induced by ligation left anterior descending artery (LAD). Ghrelin and [D-Lys3]-GHRP-6 were administered via intraperitoneal injection at the doses 200 μg/kg and 50mg/kg for 4 weeks, respectively. Left ventricular function, microvascular density (MVD), myocardial infarct size, the expression of hypoxia-inducible factor (HIF1α), vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk-1) and fms-like tyrosine kinase-1 (Flt-1), AMPK and endothelial nitric oxide synthase (eNOS) phosphorylation were examined.

RESULTS

Compared with the DM group, left ventricular ejection fraction (LVEF), fractional shortening (FS), and MVD were increased, whereas myocardial infarct size decreased remarkably in DM+ghrelin group. For the mechanism study, we found that ghrelin promoted the HIF1α, VEGF, Flk-1 and Flt-1 expression, AMPK and eNOS phosphorylation in diabetic rats. However, the above biochemical events in ghrelin treated diabetic rats were completely inhibited by GHSR-1a blocker [D-Lys3]-GHRP-6.

CONCLUSIONS

These results suggest that administration of ghrelin ameliorates impaired angiogenesis in diabetic MI rats. And these beneficial effects derive from regulating GHSR1a-mediated AMPK/eNOS signal pathway by upregulating of HIF1α, VEGF and its receptors Flk-1, Flt-1 expressions.

Effect of combined treatment with rosuvastatin and protein kinase Cβ2 inhibitor on angiogenesis following myocardial infarction in diabetic rats

The aim of the present study was to investigate the effects of combined treatment with rosuvastatin and LY333531, a selective protein kinase C (PKC)β2 inhibitor, on angiogenesis under hyperglycemic conditions. Human umbilical vein endothelial cells (HUVECs) cultured in medium containing a normal or high concentration of glucose (33.3 mmol/l) were treated with rosuvastatin (0.1 µmol/l) alone or in combination with LY333531 (10 nmol/l). HUVEC migration and tube formation were assessed. Furthermore, rats with streptozotocin-induced diabetes were randomly divided into groups and treated with either rosuvastatin alone (5 mg/kg/day) or in combination with LY333531 (10 mg/kg/day) for 4 weeks following the induction of myocardial infarction (MI). Echocardiographic patterns, the extent of myocardial fibrosis, capillary density in myocardial tissue, the phosphorylation of Akt and endothelial nitric oxide synthase (eNOS), as well as the expression levels of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-α (HIF‑1α) were assessed. The results from the in vitro experiment revealed that the tube-forming and migration ability of the HUVECs exposed to high-glucose medium was significantly improved in the group treated with the combination of rosuvastatin and LY333531. In vivo, the combination of rosuvastatin and LY333531 significantly improved left ventricular function, reduced the extent of myocardial fibrosis and increased myocardial capillary density compared to treatment with rosuvastatin alone. In addition, the expression levels of VEGF, and Akt and eNOS phosphorylation were significantly higher in the group exposed to the combination treatment than in the group treated with rosuvastatin alone. The results of the present study indicate that, compared to treatment with rosuvastatin alone, combined treatment with rosuvastatin and LY333531 promotes a greater level of angiogenesis in diabetic rats with MI. This effect is likely mediated through the upregulation of the VEGF‑dependent Akt/eNOS signaling pathway.

PKC-mediated toxicity of elevated glucose concentration on cardiomyocyte function

While it is well established that mortality risk after myocardial infarction (MI) increases in proportion to blood glucose concentration at the time of admission, it is unclear whether there is a direct, causal relationship. We investigated potential mechanisms by which increased blood glucose may exert cardiotoxicity. Using a Wistar rat or guinea-pig isolated cardiomyocyte model, we investigated the effects on cardiomyocyte function and electrical stability of alterations in extracellular glucose concentration. Contractile function studies using electric field stimulation (EFS), patch-clamp recording, and Ca2+ imaging were used to determine the effects of increased extracellular glucose concentration on cardiomyocyte function. Increasing glucose from 5 to 20 mM caused prolongation of the action potential and increased both basal Ca2+ and variability of the Ca2+ transient amplitude. Elevated extracellular glucose concentration also attenuated the protection afforded by ischemic preconditioning (IPC), as assessed using a simulated ischemia and reperfusion model. Inhibition of PKCα and β, using Gö6976 or specific inhibitor peptides, attenuated the detrimental effects of glucose and restored the cardioprotected phenotype to IPC cells. Increased glucose concentration did not attenuate the cardioprotective role of PKCε, but rather activation of PKCα and β masked its beneficial effect. Elevated extracellular glucose concentration exerts acute cardiotoxicity mediated via PKCα and β. Inhibition of these PKC isoenzymes abolishes the cardiotoxic effects and restores IPC-mediated cardioprotection. These data support a direct link between hyperglycemia and adverse outcome after MI. Cardiac-specific PKCα and β inhibition may be of clinical benefit in this setting.

Role of protein kinase C β₂ in relaxin-mediated inhibition of cardiac fibrosis

INTRODUCTION

Relaxin is a pleiotropic hormone owing endogenous antifibrosis effect on numerous organs. We demonstrated relaxin's inhibitive effect on cardiac fibrosis previously.

OBJECTIVE

The aim of this study was to investigate the role of protein kinase C (PKC) β2 in relaxin's action under high glucose conditions.

METHODS AND RESULTS

Cardiac fibroblasts (CFs) were isolated, exposed to high glucose and incubated with recombinant human relaxin (rhRLX). Western blot analysis revealed a relaxin-mediated decrease in total expression and translocation of PKCβ2, showing downregulation of PKCβ2 is involved in relaxin's action. Blocking PKCβ2 pathway with ruboxistaurin accelerated rhRLX-mediated inhibition in both proliferation of CFs and deposition of collagen.

CONCLUSION

In conclusion, relaxin can inhibit high glucose-associated cardiac fibrosis partly through PKCβ2 pathway. Further work should be done to fully understand intracellular mechanisms of relaxin's action to accelerate its clinical use.

Kalpaamruthaa modulates oxidative stress in cardiovascular complication associated with type 2 diabetes mellitus through PKC-β/Akt signaling

This study aimed at investigating the efficacy of Kalpaamruthaa (KA) on cardiovascular damage (CVD) associated with type 2 diabetes mellitus in experimental rats by reducing oxidative stress and the modulation of the protein kinase C-β (PKC-β)/Akt signaling pathway. CVD-induced rats were treated with KA (200 mg·(kg body mass)(-1)·(day)(-1)) orally for 4 weeks. KA effectively reduced insulin resistance with alterations in blood glucose, hemoglobin, and glycosylated hemoglobin in CVD-induced rats. Elevated levels of lipids in CVD-induced rats were decreased upon KA administration. In CVD-induced rats the levels of lipoproteins were returned to normal by KA treatment. KA effectively reduced the lipid peroxidative product and protein carbonyl content in liver of CVD-induced rats. KA increased the activities and (or) levels of enzymatic and nonenzymatic antioxidants in liver of CVD-induced rats. KA treatment reduced the fatty inclusion and mast cell infiltration in liver of CVD-induced rats. Further, treatment with KA reduced the chromatin condensation and marginization in myocardium of CVD-induced rats. KA alters insulin signaling by decreasing PKC-β and increasing p-Akt and GLUT4 expressions in heart of CVD-induced rats. The above findings suggest that KA renders protection against CVD induced by type 2 diabetes mellitus by augmenting the cellular antioxidant defense capacity and modulating PKC-β and the p-Akt signaling pathway.

Molecular understanding of curcumin in diabetic nephropathy

Diabetic nephropathy is characterized by a plethora of signaling abnormalities. Recent trials have suggested that intensive glucose-lowering treatment leads to hypoglycemic events, which can be dangerous. Curcumin is the active ingredient of turmeric, which has been widely used in many countries for centuries to treat numerous diseases. The preventive and therapeutic properties of curcumin are associated with its antioxidant and anti-inflammatory properties. Here, we highlight the renoprotective role of curcumin in diabetes mellitus (DM) with an emphasis on the molecular basis of this effect. We also briefly discuss the numerous approaches that have been undertaken to improve the pharmacokinetics of curcumin.

Protective effect of short-term genistein supplementation on the early stage in diabetes-induced renal damage

Hyperglycemia-induced oxidative stress has been concerned in the development of diabetic nephropathy (DN), which may cause kidney damage associated with inflammation and fibrosis. This study has been conducted to investigate the role of genistein supplementation in an acute DN state. Mice with FBG levels more than 250 mg/dL after alloxan injection (single i.p., 150 mg/kg) were considered as diabetic. Diabetic mice (DM) were further subdivided according to their FBG levels, medium-high FBG (DMMH < 450 mg/dL) and high FBG (DMH; 450 mg/dL) and were administrated by an AIG-93G diet supplemented with different doses of genistein (0, 0.025 or 0.1%). After 2 weeks' treatment, the levels of kidney malondialdehyde (MDA), blood urea nitrogen (BUN), and plasma creatinine and lipid profiles, as well as oxidative stress and inflammation-related markers, were measured (P < 0.05). Genistein supplementation improved levels of FBG in the DMMH groups, but not in the DMH group, regardless of the treatment dose. Moreover, the supplementation attenuated kidney oxidative stress indicated by MDA, BUN, and plasma creatinine. In addition, genistein treatment decreased inflammatory markers such as nuclear factor kappa B (p65), phosphorylated inhibitory kappa B alpha, C-reactive protein, monocyte chemotactic protein-1, cyclooxygenase-2, and tumor necrosis factor-alpha and improved oxidative stress markers (nuclear-related factor E2, heme oxygenase-1, glutathione peroxidase, and superoxide dismutase isoforms) in treatment groups, regardless of the genistein treatment dose. Furthermore, genistein supplementation inhibited the fibrosis-related markers (protein kinase C, protein kinase C-beta II, and transforming growth factor-beta I) in the DN state. However, 0.1% genistein supplementation in diabetes with high FBG levels selectively showed a preventive effect on kidney damage. These results suggest that genistein might be a good protective substance for DN through regulation of oxidative stress and inflammation. In particular, genistein is more efficient in diabetes patients with medium-high blood glucose levels. Finally, it is required to establish the beneficial dosage of genistein according to blood glucose levels.