Effects of Grape Seed Proanthocyanidin Extracts on Aortic Pulse Wave Velocity in Streptozocin Induced Diabetic Rats

Effects of electroacupuncture at ST36 and BL20 on the diabetic rat testis

OBJECTIVE

We aimed to evaluate the effects of electroacupuncture (EA) at ST36 and BL20 on the testicular tissues in a rat model of diabetes and to explore the mechanisms of action.

METHODS

A total of 34 male Sprague-Dawley rats were allocated to a control group (n = 10), diabetes (D) group (n = 12) or diabetes + acupuncture (DA) group (n = 12). To model diabetes, rats in groups D and DA received an intraperitoneal injection of a single dose of 35 mg/kg streptozotocin (STZ) dissolved in citrate buffer (pH = 4.5; 0.1 M) after 2 weeks of high-fat diet administration. Under xylazine/ketamine anesthesia, stainless steel needles (30 mm × 0.25 mm) were inserted bilaterally at ST36 and BL20. The needles were connected to an EA device via cables, and EA was applied for 30 min (15 Hz frequency and 0.2-1 mA intensity) twice a week for 5 weeks.

RESULTS

The effects of EA at ST36 and BL20 on blood glucose levels and body weight, biochemical parameters, histopathological, morphometric and immunohistochemical findings, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis were evaluated. A significant decrease was detected in DA versus D groups in blood glucose levels, basement membrane thickness and apoptotic cell/tubule indices. In addition, there was a significant increase in the Johnsen scores, seminiferous tubule diameters, serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone, proliferation indices, and sex hormone-binding globulin (SHBG) and insulin-like peptide 3 (INSL3) immunoreactivities.

CONCLUSION

EA had multiple positive effects on blood glucose homeostasis and testicular structure/function in this rat model of diabetes. EA may be effective at preventing or eliminating histopathological damage in the diabetic testis.

The effect of grape (Vitis vinifera) seed extract supplementation on flow-mediated dilation, blood pressure, and heart rate: A systematic review and meta-analysis of controlled trials with duration- and dose-response analysis

The objective of this systematic review and meta-analysis of controlled trials was to assess the long-term effect of grape seed extract (GSE) supplementation on flow-mediated dilation (FMD), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) in adults. Web of Science, Scopus, Medline, Cochrane Library, and Google Scholar were searched up to May 24, 2021. Nineteen trials were included in this study. Weighted mean difference (WMD) and 95% confidence interval (CI) were calculated using a random-effects model. GSE supplementation significantly reduced DBP (WMD: -2.20 mmHg, 95% CI: -3.79 to -0.60, I² = 88.8%) and HR (WMD: -1.25 bpm, 95% CI: -2.32 to -0.19, I² = 59.5%) but had no significant effects on FMD (WMD: 1.02%, 95% CI: -0.62 to 2.66, I² = 92.0%) and SBP (WMD: -3.55 mmHg, 95% CI: -7.59 to 0.49, I² = 97.4%). Subgroup analysis revealed that the dose and duration of GSE administration and the characteristics of study participants could be sources of between-study heterogeneity. Significant non-linear relationships were found between DBP and the duration of GSE supplementation (P = 0.044) and its dose (P = 0.007). In conclusion, GSE may be beneficial for individuals with or at risk of cardiovascular disease because it may have hypotensive and HR-lowering properties.

Exercise and Nutraceuticals: Eminent approach for Diabetic Neuropathy

Diabetic neuropathy is an incapacitating chronic pathological condition that encompasses a large group of diseases and manifestations of nerve damage. It affects approximately 50% of patients with diabetes mellitus. Autonomic, sensory, and motor neurons are affected. Disabilities are severe, along with poor recovery and diverse pathophysiology. Physical exercise and herbal-based therapies have the potential to decrease the disabilities associated with diabetic neuropathy. Aerobic exercises like walking, weight lifting, the use of nutraceuticals and herbal extracts are found to be effective. Literature from the public domain was studied emphasizing various beneficial effects of different exercises, use of herbal and nutraceuticals for their therapeutic action in diabetic neuropathy. Routine exercises and administration of herbal and nutraceuticals, either the extract of plant material containing the active phytoconstituent or isolated phytoconstituent at safe concentration, have been shown to have promising positive action in the treatment of diabetic neuropathy. Exercise has shown promising effects on vascular and neuronal health and has proven to be well effective in the treatment as well as prevention of diabetic neuropathy by various novel mechanisms, including herbal and nutraceuticals therapy is also beneficial for the condition. They primarily show the anti-oxidant effect, secretagogue, anti-inflammatory, analgesic, and neuroprotective action. Severe adverse events are rare with these therapies. The current review investigates the benefits of exercise and nutraceutical therapies in the treatment of diabetic neuropathy.

Beneficial effects of grape seed proanthocyanidin extract on arterial remodeling in spontaneously hypertensive rats via protecting against oxidative stress

Arterial remodeling is a pathogenic occurrence during hypertension and, in turn, is closely associated with the development and complications of hypertension. Grape seed proanthocyanidin extract (GSPE) has been reported to exhibit a protective effect on cardiovascular disease, however its effect on arterial remodeling remains to be fully elucidated. In the present study, the effects of GSPE on arterial remodeling were analyzed by treating spontaneously hypertensive rats (SHRs) with GSPE (250 mg/kg·day). Arterial remodeling was quantified through morphological methods; thoracic aortas were stained with hematoxylin-eosin or sirius red‑victoria blue. The arterial ultrastructure was imaged using transmission electron microscopy. The content of nitric oxide (NO) and endothelin‑1 (ET‑1) were examined to determine endothelial function. Oxidative stress was assessed by malondialdehyde (MDA) levels and the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). Administration of GSPE markedly alleviated hypertension‑induced arterial remodeling, which was not associated with blood pressure control. ET‑1 production was reduced, while NO production was increased in the GSPE group, which exhibited improved endothelial function. In addition, treatment with GSPE significantly ameliorated oxidative stress by improving SOD and CAT activities and reducing MDA formation. In conclusion, GSPE may attenuate hypertension‑induced arterial remodeling by repressing oxidative stress and is recommended as a potential anti‑arterial remodeling agent for patients with hypertensive vascular diseases.

Grape seed proanthocyanidin extracts prevent high glucose-induced endothelia dysfunction via PKC and NF-κB inhibition

In our study, it has been detected in vivo and in vitro that GSPE reversed high glucose-induced the increase of ICAM-1 and VCAM-1. It is shown that by western blotting detection, GSPE significantly inhibited the activation of NF-κB induced by high glucose while there was significant decrease of the expression of PKC with GSPE intervention. By adding the NF-κB blocker PDTC and the PKC inhibitor peptide 19–31(10−6 M), no significant difference was found in the levels of VCAM-1 and ICAM-1 among GSPE group, the PKC inhibitor peptide 19–31-added GSPE group and the PDTC-added GSPE group. So the conclusion could be drawn that PKC inhibition must be involved in GSPE decreasing the level of ICAM-1 and VCAM-1.We proved for the first time that GSPE prevented high glucose-induced the increase of ICAM-1 and VCAM-1 by PKC and NF-κB inhibition. These findings show a novel mechanism of the action GSPE preventing endothelial dysfunction, which may have clinical application values.

Grape seed procyanidin B2 ameliorates mitochondrial dysfunction and inhibits apoptosis via the AMP-activated protein kinase-silent mating type information regulation 2 homologue 1-PPARγ co-activator-1α axis in rat mesangial cells under high-dose glucosamine

Grape seed procyanidin B2 (GSPB2), an antioxidative and anti-inflammatory polyphenol in grape seed, has been found to have protective effects on diabetic nephropathy. Based on its favourable biological activities, in the present study, we aimed to investigate whether GSPB2 could inhibit apoptosis in rat mesangial cells treated with glucosamine (GlcN) under high-dose conditions. The results showed that the administration of GSPB2 (10 μg/ml) significantly increased the viability of mesangial cells treated with GlcN at a dose of 15 mM. We found that GSPB2 inhibited apoptosis in mesangial cells using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphates (dUTP) nick-end labelling staining and flow cytometry technique (P< 0·05 for both). GSPB2 treatment also suppressed oxidative stress by elevating the activity of glutathione peroxidase (P< 0·05) and superoxide dismutase (P< 0·01), as well as prevented cellular damage. GSPB2 enhanced the mRNA expression of nuclear respiratory factor 1, mitochondrial transcription factor A and mitochondrial DNA copy number in mesangial cells as determined by real-time PCR (P< 0·05 for each). Finally, GSPB2 treatment activated the protein expression of PPARγ co-activator-1α (PGC-1α), silent mating type information regulation 2 homologue 1 (SIRT1) and AMP-activated protein kinase (AMPK) in mesangial cells. These findings suggest that GSPB2 markedly ameliorates mitochondrial dysfunction and inhibits apoptosis in rat mesangial cells treated with high-dose GlcN. This protective effect could be, at least in part, due to the activation of the AMPK-SIRT1-PGC-1α axis.

PIMT prevents the apoptosis of endothelial cells in response to glycated low density lipoproteins and protective effects of grape seed procyanidin B2

Background

The development of diabetic angiopathy is associated with profound vascular endothelial cells (VEC) dysfunction and apoptosis. Glycated low density lipoproteins (gly-LDL) continuously produced in the setting of diabetic patients play an important role in causing VEC dysfunction and apoptosis. However, the underlying molecular mechanism remains largely elusive. Protein L-isoaspartyl methyltransferase (PIMT) is a widely expressed protein repair enzyme by multiple cell types of arterial wall including VEC. Our previous proteomic studies showed that the expression of PIMT was significantly decreased in the aorta of diabetic rats as compared with control rats and treatment with grape seed procyanidin extracts significantly increased the PIMT expression in diabetic rats. We hypothesized that PIMT plays a critical role in gly-LDL induced VEC apoptosis; grape seed procyanidin B2 (GSPB2) protect against gly-LDL induced VEC apoptosis through PIMT regulation.

Methods and Results

HUVEC transfected negative control and PIMT siRNA were treated with or without GSPB2 (10 µmol/L) for 48 h. Moreover, HUVEC of PIMT overexpression were stimulated by gly-LDL (50 µg/ml) in the presence or absence of GSPB2 (10 µmol/L) for 48 h. Our results showed that gly-LDL downregulated PIMT expression and PIMT overexpression or GSPB2 significantly attenuated gly-LDL induced VEC apoptosis. PIMT siRNA increased VEC apoptosis with up-regulation of p53, cytochrome c release, caspase-9 and caspase-3 activation. Mechanistically, overexpression of PIMT or GSPB2 increased the phosphorylation of ERK1/2 and GSK3β in the gly-LDL induced VEC.

Conclusion

In summary, our study identified PIMT as a key player responsible for gly-LDL induced VEC apoptosis and GSPB2 protect against gly-LDL induced VEC apoptosis by PIMT up-regulation. Targeting PIMT including use of GSPB2 could be turned into clinical application in the fighting against diabetic vascular complications.

Effects of losartan, HO-1 inducers or HO-1 inhibitors on erectile signaling in diabetic rats

INTRODUCTION

Activation of the renin-angiotensin system which is common in diabetes mellitus might affect heme oxygenase (HO-1) gene expression.

AIM

Assessment of the effects of administration of angiotensin II (Ang II) receptor antagonist (losartan) with HO-1 inducer or inhibitor on erectile signaling in diabetic rats.

MATERIALS AND METHODS

Seventy male rats were divided equally into seven groups; healthy controls, streptozotocin-induced diabetic rats, rats on citrate buffer, diabetic rats on losartan, diabetic rats on HO-1 inducer (cobalt protoporphyrin [CoPP]), diabetic rats on losartan and CoPP, and diabetic rats on losartan and HO-1 inhibitor (stannus mesoporphyrin [SnMP]).

MAIN OUTCOME MEASURE

HO enzyme activity, HO-1 gene expression, cyclic guanosine monophosphate (cGMP) assay, intracavernosal pressure (ICP), and cavernous tissue sinusoids surface area.

RESULTS

HO-1 gene expression, HO enzymatic activity, and cGMP were significantly decreased in the cavernous tissue of diabetic rats. These parameters were significantly elevated with the use of CoPP that restored the normal control levels of HO enzyme activity. Administration of losartan exhibited a significant enhancing effect on these parameters compared with the diabetic group, but not restored to the control levels, whereas administration of CoPP combined with losartan led to the restoration of their normal levels. ICP demonstrated significant decline in diabetic rats. The use of CoPP and/or losartan led to its significant improvement compared with diabetic rats. Administration of either losartan and/or CoPP led to a significant increase in the cavernous sinusoids surface area of diabetic rats. Administration of losartan with SnMP significantly decreased the enhancing effect of losartan on the studied parameters.

CONCLUSION

The decline in erectile function in diabetes mellitus could be attributed to the downregulation of HO-1 gene expression. HO-1 induction added to Ang II receptor antagonist could improve erectile function.