Activated platelets from diabetic rats cause endothelial dysfunction by decreasing Akt/endothelial NO synthase signaling pathway

Effects of subcutaneous vs. oral nanoparticle-mediated insulin delivery on hemostasis disorders in type 1 diabetes: A rat model study

Complications associated with Type 1 diabetes (T1D) have complex origins that revolve around chronic hyperglycemia; these complications involve hemostasis disorders, coagulopathies, and vascular damage. Our study aims to develop innovative approaches to minimize these complications and to compare the outcomes of the new approach with those of traditional methods. To achieve our objective, we designed novel nanoparticles comprising covalent organic frameworks (nCOF) loaded with insulin, termed nCOF/Insulin, and compared it to subcutaneous insulin to elucidate the influence of insulin delivery methods on various parameters, including bleeding time, coagulation factors, platelet counts, cortisol plasma levels, lipid profiles, and oxidative stress parameters. Traditional subcutaneous insulin injections exacerbated hemostasis disorder and vascular injuries in streptozotocin (STZ)-induced diabetic rats through increasing plasma triglycerides and lipid peroxidation. Conversely, oral delivery of nCOF/Insulin ameliorated hemostatic disorders and restored the endothelial oxidant/antioxidant balance by reducing lipid peroxidation and enhancing the lipid profile. Our study pioneers the understanding of how STZ-induced diabetes disrupts bleeding time, induces a hypercoagulable state, and causes vascular damage through lipid peroxidation. Additionally, it provides the first evidence for the involvement of subcutaneous insulin treatment in exacerbating vascular and hemostasis disorders in type 1 diabetes (T1D). Introducing an innovative oral insulin delivery via the nCOF approach represents a potential paradigm shift in diabetes management and patient care and promises to improve treatment strategies for type 1 Diabetes.

Ginkgolide B caused the activation of the Akt/eNOS pathway through the antioxidant effect of SOD1 in the diabetic aorta

Ginkgo biloba extract (GBE) helps lower cardiovascular disease risk. Diabetes mellitus (DM)-induced endothelial dysfunction is a critical and initiating factor in the beginning of diabetic vascular complications. It was reported that GBE causes an endothelial-dependent relaxation. This study was designed to figure out the molecular basis on which GBE protects from endothelial dysfunction in diabetes because the underlying mechanisms are unclear. Studies were performed in a normal control group and streptozotocin/nicotinamide-induced DM group. In aortas, notably diabetic aortas, GBE, and ginkgolide B (GB), a constituent of GBE, produced a dose-dependent relaxation. The relaxation by GB was abolished by prior incubation with L-NNA (an endothelial nitric oxide synthase (NOS) inhibitor), LY294002 (a phosphoinositide 3-kinase (PI3K) inhibitor), and Akt inhibitor, confirming the essential role of PI3K/Akt/eNOS signaling pathway. We also demonstrated that GB induced the phosphorylation of Akt and eNOS in aortas. The superoxide dismutase1 (SOD1) expression level decreased in DM aortas, but GB stimulation increased SOD activity and SOD1 expression in DM aortas. Our novel findings suggest that in DM aortas, endothelial-dependent relaxation induced by GB was mediated by activation of SOD1, resulting in activation of the Akt/eNOS signaling pathway.

Methylglyoxal impairs ATP- and UTP-induced relaxation in the rat carotid arteries

Although methylglyoxal (MGO), a highly reactive dicarbonyl compound, influences the functioning of the vasculature, modulating its effects on vascular reactivity to various substances remains unclear, especially purinoceptor ligands. Therefore, we sought to investigate the direct effects of MGO on relaxation induced by adenosine 5'-triphosphate (ATP) and uridine 5'-triphosphate (UTP) in isolated rat carotid arteries. When carotid arteries were exposed to MGO (420 μM for 1 h), relaxation induced by acetylcholine or sodium nitroprusside was not affected by MGO. However, ATP- and UTP-induced relaxation was impaired by MGO compared with the control. In both ATP- and UTP-induced relaxation, endothelial denudation, incubation with the nitric oxide (NO) synthase inhibitor N^G-nitro-L-arginine or the selective P2Y purinoceptor 2 (P2Y₂) receptor antagonist AR-C118925XX reduced relaxation in both the control and MGO groups, while the differences between the control and MGO groups were eliminated. The cyclooxygenase (COX) inhibitor indomethacin inhibited the differences in ATP/UTP-mediated relaxations between the control and MGO groups. Moreover, N-acetyl-L-cysteine (NAC), an antioxidant, could augment carotid arterial relaxation induced by ATP/UTP in the presence of MGO. MGO increased arachidonic acid-induced contraction, which was suppressed by NAC. Following both ATP/UTP stimulation, MGO increased the release of prostanoids. These results suggest that MGO impaired ATP- and UTP-induced relaxation in carotid arteries, which was caused by suppressed P2Y₂ receptor-mediated signaling and reductions in endothelial NO. Moreover, MGO partially contributed to COX-derived vasoconstrictor prostanoids through increased oxidative stress.

Endothelial dysfunction caused by circulating microparticles from diabetic mice is reduced by PD98059 through ERK and ICAM-1

Endothelial dysfunction contributes to the development of diabetic complications and the production of circulating microparticles (MPs). Our previous study showed that diabetic mice-derived MPs (DM MPs) had increased levels of extracellular regulated protein kinase 1/2 (ERK1/2) and impaired endothelial-dependent relaxation in aortas when compared with control mice-derived MPs. This study was designed to investigate whether PD98059, an ERK1/2 inhibitor, affects the function of aortas and DM MPs. MPs were obtained from streptozotocin-induced DM, DM after PD98059 treatment, and ICR mice as control. The mice and MPs were then analyzed on the basis of their vascular function and enzyme expressions. Compared with the controls, platelet-derived MPs and ERK1/2 levels in the MPs were significantly elevated in the DM but showed little change in PD98059-treated DM. PD98059 mainly decreased ERK1/2 phosphorylation in the MPs. In the aortas of DM and DM MPs the endothelium-dependent vascular function was impaired, and there was a significantly greater improvement in the vascular function in the PD98059-treated DM aortas and the aortas treated with PD98059-treated DM MPs than in DM aortas and the aortas treated with DM MPs. Furthermore, DM MPs increased ERK1/2 and intracellular adhesion molecule-1 (ICAM-1) expressions in the aortas, but PD98059-treated DM MPs did not show these effects. For the first time, these results indicate that PD98059 treatment improves endothelial dysfunction in DM, and adhesion properties of DM MPs can be partly blocked by PD98059 via ERK and ICAM-1. These effects may explain some of the vascular complications in diabetes.

Purinergic interplay between erythrocytes and platelets in diabetes-associated vascular dysfunction

Cardiovascular complications in diabetes are the leading causes for high morbidity and mortality. It has been shown that alteration of purinergic signaling contributes to diabetes-associated cardiovascular complications. Red blood cells (RBCs) and platelets play a fundamental role in regulation of oxygen transport and hemostasis, respectively. Of note, these cells undergo purinergic dysfunction in diabetes. Recent studies have established a novel function of RBCs as disease mediators for the development of endothelial dysfunction in type 2 diabetes (T2D). RBC-released ATP is defective in T2D, which has implication for induction of vascular dysfunction by dysregulating purinergic signaling. Platelets are hyperactive in diabetes. ADP-mediated P2Y₁ and P2Y₁₂ receptor activation contributes to platelet aggregation and targeting P2Y receptors particularly P2Y₁₂ receptor in platelets is effective for the treatment of cardiovascular events. In contrast to other P2Y₁₂ receptor antagonists, platelet-targeting drug ticagrelor has potential to initiate purinergic signaling in RBCs for the beneficial cardiovascular outcomes. It is increasingly clear that altered vascular purinergic signaling mediated by various nucleotides and nucleoside contributes to diabetes-associated vascular dysfunction. However, the contribution of complex purinergic networks between RBCs and platelets to the vascular dysfunction in diabetes remains unclear. This study discusses the possible interplay of RBCs and platelets via the purinergic network for diabetes-associated vascular dysfunction.

Flow-Mediated Dilation, a Marker of Endothelial Cell Dysfunction, in Patients with Pulmonary Hypertension

Background

Flow-mediated dilation (FMD) is considered a marker of endothelial cell dysfunction (ECD) and has been mostly evaluated in coronary artery disease. The role of ECD in the pathogenesis of pulmonary hypertension (PH) is not well-known. This study sought to evaluate the relationship between FMD and PH.

Materials and Methods

In this cross-sectional study, the FMD of the brachial artery was measured in 40 confirmed PH patients. Meanwhile, echocardiographic findings, the 6-minute walk test (6MWT), and serum pro-brain natriuretic peptide (pro-BNP) level were evaluated. Overall, 20 patients accomplished all evaluations, and their data were analyzed using SPSS software (version 23).

Results

There was an inverse relationship between pro-BNP and 6MWT (r<0, P<0.05). A significant direct relationship was observed between left ventricular ejection fraction and FMD (P=0.031). Right ventricular (RV) dilation was significantly correlated with pro-BNP (P=0.046). There was a significant direct correlation between RV function and FMD and a significant inverse relationship between pro-BNP and FMD (P=0.05). The independent t-test showed no relationship between FMD and syncope (P=0.75).

Conclusion

Endothelial cell function, which can be evaluated by FMD, was involved in patients with PH. The FMD and 6MWT were helpful as objective prognostic markers in PH. Furthermore, pro-BNP was a noninvasive indicator in the diagnosis of RV systolic dysfunction.

Amplification of the COX/TXS/TP receptor pathway enhances uridine diphosphate-induced contraction by advanced glycation end products in rat carotid arteries

Advanced glycation end products (AGEs) play a pivotal role in vascular functions under various pathophysiological conditions. Although uridine diphosphate (UDP) is an important extracellular nucleotide, the relationship between AGEs and UDP regarding their effect on vascular functions remains unclear. Therefore, we investigated the effects of AGE-bovine serum albumin (AGE-BSA) on UDP-mediated responses in rat thoracic aorta and carotid arteries. In rat thoracic aorta, UDP-induced relaxation was observed and this relaxation was similar between control (1.0 v/v% PBS) and AGE-BSA-treated (0.1 mg/mL for 60 min) groups. In contrast, contraction but not relaxation was obtained following UDP application to carotid arteries with and without endothelia; contraction was greater in the AGE-BSA-treated group than in the control group. The difference in UDP-induced contraction between the two groups was not abolished by the use of a nitric oxide synthase (NOS) inhibitor, whereas it was abolished by the use of cyclooxygenase (COX), thromboxane synthase (TXS), and thromboxane-prostanoid (TP) receptor antagonist. Further, the difference in UDP-induced contraction was not abolished by the use of a cPLA₂ inhibitor, whereas it was abolished by the use of an iPLA₂ inhibitor. UDP increased TXA₂ release in both groups, and its level was similar in both groups. Moreover, the release of PGE₂, PGF_2α, and PGI₂ was similar among the groups. Under NOS inhibition, TP receptor agonist-induced contraction increased in the AGE-BSA-treated group (vs. control group). In conclusion, the increase in UDP-induced carotid arterial contraction by AGE-BSA can be attributed to an increase in the COX/TXS/TP receptor pathway, particularly, TP receptor signaling.

Si-Miao-Yong-An Decoction Protects Against Cardiac Hypertrophy and Dysfunction by Inhibiting Platelet Aggregation and Activation

Objective: The aim of this study was to determine whether Si-Miao-Yong-An decoction (SMYAD) could ameliorate pressure overload-induced heart hypertrophy and its mechanisms.

Methods: C57BL/6 mice were subjected to either sham or transverse aortic constriction (TAC) surgery to induce heart hypertrophy. SMYAD (14.85 g/kg/day, ig) or captopril (16.5 mg/kg/day, ig) was administered to the mice for 4 weeks. Cardiac function was evaluated based on echocardiography. Heart hypertrophy was detected using hematoxylin and eosin or wheat germ agglutinin staining. Protein expression of CD41, CD61, and P-selectin were measured with Western blot and immunohistochemistry. The expression levels of atrial natriuretic peptide, brain natriuretic peptide, β-myosin heavy chain, β-thromboglobulin, and von Willebrand factor were evaluated by quantitative polymerase chain reaction.

Results: Four weeks after TAC, mice developed exaggerated cardiac hypertrophy and demonstrated a strong decrease in left ventricular ejection fraction compared with sham (29.9 ± 9.3% versus 66.0 ± 9.9%; P < 0.001). Conversely, SMYAD improved cardiac dysfunction with preserved left ventricular ejection fraction (66.5 ± 17.2%; P < 0.001). Shortening fraction was increased by SMYAD, while the left ventricular internal diameter and left ventricular volume were decreased in SMYAD group. SMYAD treatment significantly attenuated cardiac hypertrophy as reflected by the inhibition of atrial natriuretic peptide, brain natriuretic peptide, β-myosin heavy chain mRNA expression, and by the decreasing of cardiac myocyte cross-sectional area. Furthermore, Western blot and immunohistochemistry indicated that the protein expression of platelet aggregation markers (CD41 and CD61) and platelet activation marker (P-selectin) were significantly higher in model mice compared with control. These pathological alterations in TAC-induced mice were significantly ameliorated or blocked by SMYAD administration.

Conclusions: Our results suggested that SMYAD exerted its effect by inhibiting platelet aggregation and activation as revealed by CD41/CD61/P-selectin downregulation. Inhibition the activation of the platelets might contribute to the therapeutic effect of SMYAD in failing heart.

ERK-containing microparticles from a diabetic mouse induce endothelial dysfunction

Endothelial dysfunction is a hallmark of diabetic vascular complications. Microparticles (MPs) are small vesicles shed from the surface of blood and vascular cells that act as stimuli and during apoptosis. Circulating MPs of diabetic rats have been shown to induce endothelial dysfunction. However, the underlying mechanisms require further study. In this study, we investigated how MPs from diabetic mice affect endothelial function. MPs were collected from streptozotocin-induced diabetic mice and Institute of Cancer Research (ICR) mice as controls. The levels of MPs were assessed and characterized by flow cytometry, enzyme-linked immunosorbent assay and dot blotting. Normal mice aortas were incubated with MPs and expressions of enzymes and vascular relaxation were analyzed. We found that (1) circulating MPs level increased in diabetic mice; (2) MPs impaired endothelial-dependent relaxation in mice aorta, but diabetic mice-derived MPs (diabetes mellitus (DM) MPs) were easier to attach to the endothelial cells than were control MPs; (3) DM MPs had more extracellular signal-regulated kinase (ERK)1/2 than did control mice-derived MPs, and they induced ERK1/2 activation in mice aortas; (4) DM MPs decreased endothelial nitric oxide synthase (eNOS) in mice aortas, and eNOS was emitted from endothelial cells to blood in the shape of endothelial MPs. DM MPs significantly altered endothelial function by activation of ERK1/2, which might provide a therapeutic target for diabetic vascular complications.

Therapeutic Potential of Ginsenosides as an Adjuvant Treatment for Diabetes

Ginseng, one of the oldest traditional Chinese medicinal herbs, has been used widely in China and Asia for thousands of years. Ginsenosides extracted from ginseng, which is derived from the roots and rhizomes of Panax ginseng C. A. Meyer, have been used in China as an adjuvant in the treatment of diabetes mellitus. Owing to the technical complexity of ginsenoside production, the total ginsenosides are generally extracted. Accumulating evidence has shown that ginsenosides exert antidiabetic effects. In vivo and in vitro tests revealed the potential of ginsenoside Rg1, Rg3, Rg5, Rb1, Rb2, Rb3, compound K, Rk1, Re, ginseng total saponins, malonyl ginsenosides, Rd, Rh2, F2, protopanaxadiol (PPD) and protopanaxatriol (PPT)-type saponins to treat diabetes and its complications, including type 1 diabetes mellitus, type 2 diabetes mellitus, diabetic nephropathy, diabetic cognitive dysfunction, type 2 diabetes mellitus with fatty liver disease, diabetic cerebral infarction, diabetic cardiomyopathy, and diabetic erectile dysfunction. Many effects are attributed to ginsenosides, including gluconeogenesis reduction, improvement of insulin resistance, glucose transport, insulinotropic action, islet cell protection, hepatoprotective activity, anti-inflammatory effect, myocardial protection, lipid regulation, improvement of glucose tolerance, antioxidation, improvement of erectile dysfunction, regulation of gut flora metabolism, neuroprotection, anti-angiopathy, anti-neurotoxic effects, immunosuppression, and renoprotection effect. The molecular targets of these effects mainly contains GLUTs, SGLT1, GLP-1, FoxO1, TNF-α, IL-6, caspase-3, bcl-2, MDA, SOD, STAT5-PPAR gamma pathway, PI3K/Akt pathway, AMPK-JNK pathway, NF-κB pathway, and endoplasmic reticulum stress. Rg1, Rg3, Rb1, and compound K demonstrated the most promising therapeutic prospects as potential adjuvant medicines for the treatment of diabetes. This paper highlights the underlying pharmacological mechanisms of the anti-diabetic effects of ginsenosides.

Relationship between PDK1 and contraction in carotid arteries in Goto-Kakizaki rat, a spontaneous type 2 diabetic animal model

We studied the relationship between 3-phosphoinositide-dependent protein kinase 1 (PDK1) and contractions induced by serotonin, phenylephrine, and thromboxane A2 mimetic (U46619) in the presence of nitric oxide synthase inhibitor in the carotid arteries of Goto-Kakizaki (GK) rats, a spontaneous type 2 diabetic model, in the chronic stage of disease. Serotonin-induced contraction was greater in the GK rats than in the control Wistar rats. A specific PDK1 inhibitor (GSK2334470) decreased the serotonin-induced contraction in the GK rats but not in the Wistar rats, and the difference in such contraction was abolished with this treatment. In GK rats, phenylephrine-induced contraction exhibited a leftward shift and U46619-induced contraction was greater still. Phenylephrine- and U46619-induced contractions were reduced by GSK2334470 in both groups. These results suggest, for the first time, that the contribution of PDK1 is different among 3 vasoconstrictors and that PDK1 contributed to increased serotonin-induced contraction in the carotid arteries of GK rats.

MiR-181c restrains nitration stress of endothelial cells in diabetic db/db mice through inhibiting the expression of FoxO1

Endothelial dysfunction played an important role in the progression of diabetes mellitus (DM). miR-181c has been implicated in many diseases, including DM. However, the molecular mechanisms of miR-181c regulate this process remained poorly understood. Healthy ICR mice were divided into control group (n = 10) and db/db DM group (n = 10). The expression of miR-181c and FoxO1 were both investigated in diabetic db/db mice or high glucose-induced endothelial cells (MAECs and END-D). Here we found that down-regulation of miR-181c and the activation of FoxO1/iNOS were observed in mice and endothelial cells. Furthermore, we verified that miR-181c directly targeted and inhibited FoxO1 gene expression by targeting its 3'-UTR through luciferase reporter assay. Knockdown of FoxO1 reversed the up-regulation of iNOS, nitrotyrosine and the down-regulation of p-eNOS^Ser1177/eNOS in high glucose (30 mM)-induced MAECs cells. In addition, over-expression of miR-181c could reverse the enhanced nitration stress induced by high glucose, while this effect could be attenuated by pcDNA-FoxO1 in MAECs. These results shown that miR-181c attenuated nitration stress through regulating FoxO1 expression and affecting endothelial cell function, which offering a new target for the development of preventive or therapeutic agents against DM.

Relaxation Induced by Atrial Natriuretic Peptide Is Impaired in Carotid but Not Renal Arteries from Spontaneously Hypertensive Rats Due to Reduced BKCa Channel Activity

Atrial natriuretic peptide (ANP) plays an important role in vascular functions such as blood pressure regulation and relaxant activity. Individual vascular beds exhibit differences in vascular reactivity to various ligands, however, the difference in responsiveness to ANP between carotid and renal arteries and the molecular mechanisms of its vasorelaxant activity in a pathophysiological state, including hypertension, remain unclear. We therefore investigated this issue by exposing carotid and renal artery rings obtained from spontaneously hypertensive rats (SHR) to ANP. In the SHR artery (vs. control WKY artery), the ANP-induced relaxations were reduced in carotid artery but not renal artery. Acetylcholine-induced relaxations were reduced in both arteries in SHR (vs. WKY). Sodium nitroprusside-induced relaxation was similar in both arteries between the groups. In carotid arteries, the ANP-induced relaxation was not affected by endothelial denudation or by treatment with inhibitors of nitric oxide synthase, cyclooxygenase, the voltage-dependent potassium channel, or ATP-sensitive potassium channel in arteries from both SHR and WKY. In the carotid artery from WKY but not SHR, the ANP-induced relaxation was significantly reduced by inhibition of the large-conductance calcium-activated potassium channel (BKCa). The BKCa activator-induced relaxation was reduced in the SHR artery (vs. WKY). These results suggest that ANP-induced relaxation is impaired in the carotid artery from SHR and this impairment may be at least in part due to the reduction of BKCa activity rather than endothelial components.

Circulating microparticles from diabetic rats impair endothelial function and regulate endothelial protein expression

AIM

Diabetes mellitus increases the risk of cardiovascular disease, which is accompanied by functional and structural changes in the vascular system. Microparticles (MPs) have been described as biological vectors of endothelial dysfunction in other pathologies. However, the molecular mechanisms underlying their formation and signalling are unclear. We investigated the role of MPs derived from streptozotocin (STZ)-induced diabetic rats in endothelial function.

METHODS

Male Wistar rats were injected with STZ to induce diabetes, and MPs isolated from control or STZ-induced diabetic rats were characterized by dot blotting (assessed by CD62P detections), flow cytometry (assessed by annexin V detections) and ELISA. Carotid arteries from rats were incubated with MPs, and expressions of enzymes and endothelium-dependent relaxation were analysed.

RESULTS

The circulating levels of MPs, particularly the levels of platelet-derived microparticles, from diabetic rats were higher than those present in controls. Endothelium-dependent relaxation induced by acetylcholine (ACh) was attenuated in carotid arteries from STZ-induced diabetic rats. Following the incubation of control carotid arteries with MPs isolated from STZ rats, ACh-induced endothelium-dependent relaxation was impaired, but MPs isolated from control rats had no such effect. Furthermore, the effect of MPs was mediated by a decrease in expression of endothelial nitric oxide synthase (eNOS) and the overexpression of caveolin-1.

CONCLUSION

Circulating MPs isolated from STZ-induced diabetic rats induce endothelial dysfunction in carotid arteries and regulate protein expressions of eNOS and caveolin-1. These data advance our understanding of the deleterious effects of circulating MPs observed in disorders with diabetic complications.

Platelets in the Alzheimer's disease brain: do they play a role in cerebral amyloid angiopathy?

Alzheimer’s disease (AD) is characterized by extracellular beta-amyloid plaques and intracellular tau tangles. AD-related pathology is often accompanied by vascular changes. The predominant vascular lesions in AD are cerebral amyloid angiopathy (CAA) and arteriosclerosis. Platelets circulate along the vessel wall responding immediately to vascular injury. The aim of the present study was to explore the presence and migration of platelets (thrombocytes) to sites of small vascular bleedings and/or to beta-amyloid plaques in the brain. We infused fluorescently labeled red PKH26 mouse platelets into transgenic Alzheimer mice overexpressing APP with Swedish/Dutch/Iowa mutations (APP_SDI) and explored if platelets migrate into the brain. Further we studied whether platelets accumulate in the vicinity of β-amyloid plaques. Our animal data shows that infused platelets are found in the liver and partly in the lung, while in the brain platelets were visible to a minor degree. In mice, we did not observe a significant association of platelets with beta-amyloid plaques or vessels. In the brain of Alzheimer postmortem patients platelets could be detected by immunohistochemistry for CD41 and CD62P, but the majority was found in vessels with or without beta-amyloid load, and only a few single platelets migrated deeper into the brain. Our findings suggest that platelets do not migrate into the brains of Alzheimer disease but are concentrated in brain vessels.

Microparticle levels after arterial injury and NO therapy in diabetes

BACKGROUND

Little is known about how arterial injury, nitric oxide (NO), or the diabetic milieu impact microparticle (MP) levels in the vasculature. We hypothesized that MP levels would increase following local arterial injury, and that NO would modify MP levels differently based on the metabolic environment.

MATERIALS AND METHODS

Type 1 diabetes was induced in male Lean Zucker (LZ) rats with streptozotocin, and type 2 diabetes was induced in male Zucker diabetic fatty rats through diet. Lean Zucker rats served as nondiabetic controls. The rat carotid balloon injury was performed ± NO (n > 4/group). Blood was obtained at intervals from baseline to 14 d after injury and analyzed for platelet MP (PMP), leukocyte MP (LMP), and endothelial MP (EMP) using fluorescence-activated cell sorting (FACS) analysis.

RESULTS

At baseline, type 1 diabetic rats had the highest EMP levels (P < 0.05). After arterial injury, type 1 and type 2 diabetic rats had a transient increase in EMP levels (P < 0.05) before decreasing below baseline levels. Both LMP and PMP levels generally declined after injury in all three animal models but were the lowest in both type 1 and type 2 diabetic rats. NO therapy had little impact on MP levels in nondiabetic and type 1 diabetic rats after injury. Conversely, NO caused a dramatic increase in EMP, LMP, and PMP levels in type 2 diabetic animals at early time points after injury (P < 0.05).

CONCLUSIONS

These data demonstrate that the diabetic milieu impacts MP levels at baseline, after arterial injury and with NO treatment.

Stimulation of nitric oxide production contributes to the antiplatelet and antithrombotic effect of new peptide pENW (pGlu-Asn-Trp)

INTRODUCTION

New peptide pGlu-Asn-Trp (pENW), initially extracted from snake venom, significantly attenuates the formation of arterial and venous thrombi in vivo, and has modest in-vitro antiplatelet activity. This study was designed to investigate the underlying mechanisms.

METHODS

The rat carotid thrombosis model induced by FeCl3 was established to evaluate the antithrombotic activity of pENW. The effects of pENW on the production of nitric oxide (NO), as well as the expression and activity of endothelial nitric oxide synthase (eNOS), were determined. The vasorelaxant effect of pENW was evaluated using isolated rat aortic rings in the absence or presence of N(G)-nitro-L-arginine methyl ester (L-NAME, eNOS inhibitor). Furthermore, the in-vitro antiplatelet activity of pENW was investigated with the addition of sodium nitroprusside (SNP, NO donor) and/or L-NAME to further prove the role of NO and eNOS in the inhibitory effect of pENW on platelet aggregation.

RESULTS

In vivo, pENW inhibited thrombus formation induced by endothelial injury in a dose-dependent manner, with a significantly prolonged time to the occurrence of arterial occlusion. It was shown that pENW offered protection for blood vessels from oxidative injury. pENW significantly increased NO production in rats treated with pENW at 4 or 2mg/kg body weight. Furthermore, the production of NO from the cultured vascular endothelial cells was increased with the treatment of 10(-4)M and 10(-5)M pENW; pENW also enhanced eNOS expression and activity both in vivo and in vitro, and elicited a concentration-dependent vasorelaxation which was significantly inhibited by L-NAME. Notably, pENW inhibited ADP-induced platelet aggregation, and the inhibition was more significant in the presence of NO. The inhibition of platelet aggregation by pENW was significantly abolished by L-NAME.

CONCLUSIONS

The in-vivo antiplatelet and antithrombotic effects of pENW are at least partly mediated by the increased production of endogenous NO via up-regulation and stimulation of eNOS. The findings suggest that pENW could potentially be developed as a novel therapeutic agent in the treatment of platelet-driven disorders.

RhoA/mDia-1/profilin-1 signaling targets microvascular endothelial dysfunction in diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a major cause of blindness in the working-age populations of developed countries, and effective treatments and prevention measures have long been the foci of study. Patients with DR invariably demonstrate impairments of the retinal microvascular endothelium. Many observational and preclinical studies have shown that angiogenesis and apoptosis play crucial roles in the pathogenesis of DR. Increasing evidence suggests that in DR, the small guanosine-5'-triphosphate-binding protein RhoA activates its downstream targets mammalian Diaphanous homolog 1 (mDia-1) and profilin-1, thus affecting important cellular functions, including cell morphology, motility, secretion, proliferation, and gene expression. However, the specific underlying mechanism of disease remains unclear.

CONCLUSION

This review focuses on the RhoA/mDia-1/profilin-1 signaling pathway that specifically triggers endothelial dysfunction in diabetic patients. Recently, RhoA and profilin-1 signaling has attracted a great deal of attention in the context of diabetes-related research. However, the precise molecular mechanism by which the RhoA/mDia-1/profilin-1 pathway is involved in progression of microvascular endothelial dysfunction (MVED) during DR has not been determined. This review briefly describes each feature of the cascade before exploring the most recent findings on how the pathway may trigger endothelial dysfunction in DR. When the underlying mechanisms are understood, novel therapies seeking to restore the endothelial homeostasis comprised in DR will become possible.

The impact of umbilical blood flow regulation on fetal development differs in diabetic and non-diabetic pregnancy

BACKGROUND/AIMS

Diabetes is well-known to influence endothelial function. Endothelial function and blood flow regulation might be different in diabetic and non-diabetic pregnancy. However, the impact of umbilical blood flow regulation in gestational diabetes on fetal development is unknown so far.

METHODS

In a prospective birth cohort study, we analyzed the association of the umbilical artery Doppler indices (pulsatility index, resistance index and systolic/diastolic ratio) and fetal size measures (biparietal diameter, head circumference, abdominal circumference, femur length and birth weight) in 519 non-gestational diabetes mellitus pregnancies (controls) and 226 gestational diabetes mellitus pregnancies in middle (day 160.32 ±16.29 of gestation) and late (day 268.12 ±13.04 of gestation) pregnancy.

RESULTS

Multiple regression analysis considering confounding factors (gestational day of ultrasound examination, offspring sex, maternal body mess index before pregnancy, maternal age at delivery, maternal body weight at delivery and maternal hypertension) showed that umbilical artery Doppler indices (pulsatility index, resistance index and systolic/diastolic ratio) were associated with fetal head circumference and femur length in middle gestational diabetes mellitus pregnancy but not in non-gestational diabetes mellitus pregnancy. Head circumference, biparietal diameter, abdominal circumference and femur length in mid gestation were smaller in fetus of gestational diabetes mellitus pregnancy versus non-gestational diabetes mellitus pregnancy. In contrast to non-gestational diabetes mellitus pregnancy in late gestation, umbilical artery Doppler indices in gestational diabetes mellitus pregnancy were not associated with ultrasound measures of fetal growth. Birth weight was slightly increased in gestational diabetes mellitus pregnancy as compared to non-gestational diabetes mellitus pregnancy.

CONCLUSIONS

The impact of umbilical blood flow on fetal growth is time dependent in human gestational diabetes mellitus and non-gestational diabetes mellitus pregnancy. In gestational diabetes mellitus pregnancy umbilical blood flow is critical for organ development in much earlier stages of pregnancy as compared to non-gestational diabetes mellitus pregnancy. The physiological and molecular pathways why there is a catch up growth in later times of gestational diabetes mellitus pregnancy resulting in larger gestational diabetes mellitus babies at birth needs to be addressed in further studies.