Sitagliptin protects diabetic rats with acute myocardial infarction through induction of angiogenesis: role of IGF-1 and VEGF

Cardioprotective Effect of Flibanserin against Isoproterenol-Induced Myocardial Infarction in Female Rats: Role of Cardiac 5-HT2A Receptor Gene/5-HT/Ca2+ Pathway

Myocardial infarction (MI) is a life-threatening ischemic disease and is one of the leading causes of morbidity and mortality worldwide. Serotonin (5-HT) release during myocardial ischemia plays an important role in the progression of myocardial cellular injury. This study was conducted to investigate the possible cardioprotective effect of flibanserin (FLP) against isoproterenol (ISO)-induced MI in rats. Rats were randomly divided into five groups and were treated orally (p.o.) with FLP (15, 30, and 45 mg/kg) for 28 days. ISO was administered subcutaneously (S.C.) (85 mg/kg) on the 27th and 28th days to induce MI. ISO-induced myocardial infarcted rats exhibited a significant increase in cardiac markers, oxidative stress markers, cardiac and serum 5-HT levels, and total cardiac calcium (Ca2+) concentration. ISO-induced myocardial infarcted rats also revealed a remarkable alteration of electrocardiogram (ECG) pattern and significantly upregulated expression of the 5-Hydroxytryptamine 2A (5-HT2A) receptors gene. Moreover, ISO-induced myocardial infarcted rats showed significant histopathological findings of MI and hypertrophic signs. However, pretreatment with FLP significantly attenuated the ISO-induced MI in a dose-dependent manner, as the effect of FLP (45 mg/kg) was more pronounced than that of the other two doses, FLP (15 and 30 mg/kg). The present study provides evidence for the cardioprotective efficacy of FLP against ISO-induced MI in rats.

Characterization, antibacterial, antioxidant, antidiabetic, and anti-inflammatory activities of green synthesized silver nanoparticles using Phragmanthera austroarabica A. G. Mill and J. A. Nyberg extract

Introduction

Diabetes mellitus is a chronic metabolic disorder that exhibited great expansion all over the world. It is becoming an epidemic disease adding a major burden to the health care system, particularly in developing countries.

Methods

The plant under investigation in the current study Phragmanthera austroarabica A. G. Mill and J. A. Nyberg is traditionally used in Saudi Arabia for the treatment of diabetes mellitus. The methanolic extract (200 mg/kg) of the plant and pure gallic acid (40 mg/kg), a major metabolite of the plant, as well as their silver nanoparticle formulae (AgNPs) were evaluated for their antidiabetic activity.

Results and Discussion

The results showed a decrease in body fat, obesity, an improvement in lipid profiles, normalization of hyperglycemia, insulin resistance, and hyperinsulinemia, and an improvement in liver tissue structure and function. However, the results obtained from AgNPs for both extract and the pure gallic acid were better in most measured parameters. Additionally, the activity of both the crude extract of the plant and its AgNPs were evaluated against a number of gram-positive, gram-negative bacteria and fungi. Although the activity of the crude extract ranged from moderate to weak or even non-active, the AgNPs of the plant extract clearly enhanced the antimicrobial activity. AgNPs of the extract demonstrated remarkable activity, especially against the Gram-negative pathogens Proteus vulgaris (MIC 2.5 μg/ml) and Pseudomonas aeruginosa (MIC 5 μg/ml). Furthermore, a promising antimicrobial activity was shown against the Gram-positive pathogen Streptococcus mutants (MIC 1.25 μg/ml).

Sitagliptin attenuates neuronal apoptosis via inhibiting the endoplasmic reticulum stress after acute spinal cord injury

Regulation of endoplasmic reticulum stress (ER) stress-induced apoptosis and nerve regeneration is a hopeful way for acute spinal cord injury (SCI). Sitagliptin (Sita) is one of dipeptidyl peptidase-4 (DPP-4) inhibitor, which is beneficial neurons damaged diseases. However, its protective mechanisms of avoiding nerve injury remain unclear. In this study, we further investigated the mechanism of the anti-apoptotic and neuroprotective effects of Sita in promoting locomotor recovery from SCI. In vivo results showed that Sita treatment reduced neural apoptosis caused by SCI. Moreover, Sita effectively attenuated the ER tress and associated apoptosis in rats with SCI. A striking feature was the occurrence of nerve fiber regeneration at the lesion site, which eventually led to significant locomotion recovery. In vitro results showed that the PC12 cell injury model induced by Thapsigargin (TG) also showed similar neuroprotective effects. Overall, sitagliptin showed potent neuroprotective effects by targeting the ER stress-induced apoptosis both in vivo and vitro, thus facilitating the regeneration of the injured spinal cord.

Cardiovascular protection by DPP-4 inhibitors in preclinical studies: an updated review of molecular mechanisms

Dipeptidyl peptidase 4 (DPP4) inhibitors are a class of antidiabetic medications that cause glucose-dependent increase in incretins in diabetic patients. One of the two incretins, glucagon-like peptide-1 (GLP-1), beside its insulinotropic activity, has been studied for extra pancreatic effects. Most of DPP4 inhibitors (DPP4i) have been investigated in in vivo and in vitro models of diabetic and nondiabetic cardiovascular diseases including heart failure, hypertension, myocardial ischemia or infarction, atherosclerosis, and stroke. Results of preclinical studies proved prominent therapeutic potential of DPP4i in cardiovascular diseases, regardless the presence of diabetes. This review aims to present an updated summary of the cardiovascular protective and therapeutic effects of DPP4 inhibitors through the past 5 years focusing on the molecular mechanisms beneath these effects. Additionally, based on the results summary presented here, future studies may be conducted to elucidate or illustrate some of these findings which can add clinical benefits towards management of diabetic cardiovascular complications.

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles loaded with miR-223 ameliorate myocardial infarction through P53/S100A9 axis

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been proposed as a promising strategy for myocardial infarction (MI). This study aims to explore the mechanism of human umbilical cord MSCs (hucMSCs)-derived EVs loaded with miR-223 on MI. Inflammation, cell biological functions, and fibrosis in vitro were measured. Furthermore, MI rat models were established to verify the role of EVs-miR-223 in vivo. The binding relationship between miR-223 and P53 was confirmed. ChIP assay was utilized to observe the combination of P53 and S100A9. The suppressed fibrosis of cardiomyocytes occurred with cells overexpressing miR-223. MiR-223 contributed to the angiogenesis of HUVECs. P53 was a target gene of miR-223. In vivo, miR-223 relieved myocardial fibrosis and inflammation infiltration, and promoted the angiogenesis in MI rats. HucMSC-derived EVs loaded with miR-223 mitigates MI and promotes myocardial repair through the P53/S100A9 axis, manifesting the underlying therapy values of hucMSC-derived EVs loaded with miR-223 in MI.

Sitagliptin Modulates Oxidative, Nitrative and Halogenative Stress and Inflammatory Response in Rat Model of Hepatic Ischemia-Reperfusion

A possibility of repurposing sitagliptin, a well-established antidiabetic drug, for alleviating injury caused by ischemia-reperfusion (IR) is being researched. The aim of this study was to shed some light on the molecular background of the protective activity of sitagliptin during hepatic IR. The expression and/or concentration of inflammation and oxidative stress-involved factors have been determined in rat liver homogenates using quantitative RT-PCR and Luminex^® xMAP^® technology and markers of nitrative and halogenative stress were quantified using targeted metabolomics (LC-MS/MS). Animals (n = 36) divided into four groups were treated with sitagliptin (5 mg/kg) (S and SIR) or saline solution (C and IR), and the livers from IR and SIR were subjected to ischemia (60 min) and reperfusion (24 h). The midkine expression (by 2.2-fold) and the free 3-nitrotyrosine (by 2.5-fold) and IL-10 (by 2-fold) concentration were significantly higher and the Nox4 expression was lower (by 9.4-fold) in the IR than the C animals. As compared to IR, the SIR animals had a lower expression of interleukin-6 (by 4.2-fold) and midkine (by 2-fold), a lower concentration of 3-nitrotyrosine (by 2.5-fold) and a higher Nox4 (by 2.9-fold) and 3-bromotyrosine (by 1.4-fold). In conclusion, IR disturbs the oxidative, nitrative and halogenative balance and aggravates the inflammatory response in the liver, which can be attenuated by low doses of sitagliptin.

Role of sodium glucose cotransporter type 2 inhibitors dapagliflozin on diabetic nephropathy in rats; Inflammation, angiogenesis and apoptosis

AIMS

Diabetic nephropathy is a major cause of chronic kidney disease and end-stage renal failure worldwide. Dapagliflozin Sodium-glucose co-transporter 2 (SGLT2) inhibitor is a new class of diabetic medications prescribed for the treatment of type 2 diabetes. The current study investigates the possible impact of dapagliflozin (DAPA) on inflammations, apoptosis, angiogenesis and fibrosis in early-stage diabetic nephropathy using a rat model of type 2 diabetes.

MAIN METHODS

Rats were divided into five groups, group1: normal vehicle group, group 2: diabetic group, group 3: diabetic+ DAPA (0.75 mg/kg), group 4: diabetic+DAPA (1.5 mg/kg), group 5: diabetic+DAPA (3 mg/kg). At the end of the study, Blood glucose level was measured. Serum insulin, BUN, and SCr were measured. Insulin resistance was determined using the homeostasis model assessment for insulin resistance (HOMA-IR) index. Renal tissue homogenization was done for assessment of inflammatory markers TNF-α, PEDF, and PTX-3, In addition to apoptosis markers BCL-2 and BAX. Histopathological examinations were done for tubular renal cells and immunohistochemical examination for fibrosis marker α-SMA and angiogenic factor VEGF.

KEY FINDINGS

Treatments with dapagliflozin showed improvements in histopathological examinations, inflammatory and apoptotic markers compared to diabetic vehicles in a dose-dependent manner.

SIGNIFICANCE

Thus, dapagliflozin may have renoprotective effects, which be promising in diabetic patients suffered from nephropathy.

Anti-inflammatory and protective effects of combined treatment with sitagliptin and melatonin in cardiac ischemia reperfusion injury in obese rats: Involvement of TLR-4/NF-κB pathway

Background: Obesity is associated with an augmented risk of myocardial ischemia/reperfusion (I/R) injury. Reduction of I/R injury by effective cardioprotective strategies needs to be investigated in obese subjects. This study aimed to evaluate the combined effects of sitagliptin and melatonin on inflammatory response and TLR4/IκBα/NF-κB signaling following cardiac I/R damage in obese rats. Methods: Sixty-six male Wistar rats (180–200 g) were fed a low fat diet (10% Kcal from lipids) or high fat (45% Kcal from lipids) diets for 12 weeks. High fat-fed (obese) rats experienced 30 min left anterior descending occlusion followed by 24 h reperfusion. Obese rats received sitagliptin (20 mg/kg/day) for 1 month before I/R surgery. Melatonin (10 mg/kg) was injected at early reperfusion. Myocardial infarct size (IS), cTn-I release, pro-inflammatory cytokines, myeloperoxidase (MPO), COX-2 and iNOS, and the protein expressions of TLR4, p-NF-κB/p65, and p-IκBα were evaluated. Results: Monotherapies with sitagliptin-preconditioning or melatonin-postconditioning had no cardioprotective effects in obese rats. However, combined therapy with sitagliptin and melatonin significantly reduced IS, and the release of cTn-I, in comparison to untreated obese rats ( p < .01) Moreover, this combination decreased the production of pro-inflammatory cytokines, MPO, COX-2 and iNOS, and the expression of TLR4 and p-NF-κB/p65, while reduced the expression of p-IκBα, in comparison with untreated or monotherapies-received obese rats ( p < .01 for all). Conclusion: Combination therapy with sitagliptin and melatonin was a good cardioprotective strategy to modulate the inflammatory responses and TLR4/NF-κB signaling pathway in obese patients with cardiac I/R injury.

Resveratrol Improves Bnip3-Related Mitophagy and Attenuates High-Fat-Induced Endothelial Dysfunction

Statin treatment reduces cardiovascular risk. However, individuals with well-controlled low-density lipoprotein (LDL) levels may remain at increased risk owing to persistent high triglycerides and low high-density lipoprotein cholesterol. Because resveratrol promotes glucose metabolism and mitigates cardiovascular disorders, we explored its mechanism of protective action on high-fat-induced endothelial dysfunction. Human umbilical venous endothelial cells were treated with oxidized LDL (ox-LDL) in vitro. Endothelial function, cell survival, proliferation, migration, and oxidative stress were analyzed through western blots, quantitative polymerase chain reaction, ELISA, and immunofluorescence. ox-LDL induced endothelial cell apoptosis, proliferation arrest, and mobilization inhibition, all of which resveratrol reduced. ox-LDL suppressed the activities of mitochondrial respiration complex I and III and reduced levels of intracellular antioxidative enzymes, resulting in reactive oxygen species overproduction and mitochondrial dysfunction. Resveratrol treatment upregulated Bnip3-related mitophagy and prevented ox-LDL-mediated mitochondrial respiration complexes inactivation, sustaining mitochondrial membrane potential and favoring endothelial cell survival. We found that resveratrol enhanced Bnip3 transcription through hypoxia-inducible factor 1 (HIF1) and 5' AMP-activated protein kinase (AMPK). Inhibition of AMPK and HIF1 abolished resveratrol-mediated protection of mitochondrial redox balance and endothelial viability. Together, these data demonstrate resveratrol reduces hyperlipemia-related endothelial damage by preserving mitochondrial homeostasis.

Cardioprotective effect of thymol against adrenaline-induced myocardial injury in rats

Cardiovascular disease represents a vital global disease burden. This study aims to assess the possible cardioprotective effect of thymol against adrenaline-induced myocardial injury (MI) in rats. Furthermore the effect of thymol on cardiac function biomarkers, electrocardiogram (ECG) alterations, oxidative stress, inflammation, apoptosis and histopathological changes was assessed. MI was induced by adrenaline (2 mg/kg, s.c.) injected as a single dose for 2 consecutive days (24 h apart). Normal and control groups received the vehicle for 21 consecutive days. The other 3 groups were orally administered thymol (15, 30, 60 mg/kg) for 21 consecutive days and on day 22, adrenaline was injected as a single dose for 2 consecutive days. Then ECG examination, biochemical, histopathological, immunohistochemical analyses were carried out. Thymol reversed adrenaline-induced reduction of heart rate, prolongation of RR interval and elevation of ST interval. Thymol pretreatment significantly reduced serum aspartate dehydrogenase (AST), lactate dehydrogenase (LDH), and creatine kinase (CK) levels in MI rats. Oral pretreatment with thymol increased reduced glutathione (GSH), reduced malondialdehyde (MDA), nuclear factor-kappa B (NF-κB), and interleukin-1β (IL-1β) cardiac contents in MI rats. Additionally, thymol administration significantly decreased protein expression of caspase-3, increased Bcl-2 protein expression in cardiac tissue and ameliorated histopathological changes. This study reveals that thymol exerted cardioprotective effect against adrenaline-induced MI in rats evidenced by improving cardiac function, attenuating ECG and histopathological changes which may be partly mediated through its anti-oxidant, anti-inflammatory and anti-apoptotic effect.

Detrimental Effect of Sitagliptin Induced Autophagy on Multiterritory Perforator Flap Survival

Multiterritory perforator flap survival is commonly applied in surgical tissue reconstructions and covering of large skin defects. However, multiple risk factors such as ischemia, reperfusion injury, and apoptosis after reconstructive surgeries cause necrosis in distal parts with outcomes ranging from poor aesthetic appearance to reconstructive failure. A few studies have reported that sitagliptin (Sit) promotes angiogenesis and inhibits apoptosis. However, little is known about Sit-induced autophagy especially on the flap model. Therefore, our study investigated the effect of Sit and its induced autophagy on the perforator flap survival. Ninety male Sprague-Dawley rats were randomly separated into control, Sit, and Sit+3-methyladenine group. Results revealed that Sit significantly promoted flap survival by enhancing angiogenesis, reducing oxidative stress, and attenuating apoptosis. In addition, flap survival was further improved after co-administration with 3-methyladenine to inhibit autophagy. Overall, our results established that Sit has positive effects in promoting survival of multiterritory perforator flap. Sit-induced autophagy was detrimental for flap survival and its inhibition may further improve flap survival.