Liraglutide treatment improves the coronary microcirculation in insulin resistant Zucker obese rats on a high salt diet

Liraglutide improves antioxidant defense in hearts of spontaneously hypertensive female rats independently of changes in blood pressure in a pre-clinical model of menopause

Liraglutide (LIRA) is an agonist of the GLP-1 receptor used in the treatment of type 2 diabetes with a cardioprotective effect, although little is known about the effects of LIRA in post-menopause. We aimed to evaluate the effects of LIRA in the cardiovascular system of ovariectomized spontaneously hypertensive rats (SHR). SHR rats were separated into two groups: ovariectomized (saline) and ovariectomized + liraglutide (0.6 and 1.2 mg/kg for 4+4 weeks, respectively). Systolic blood pressure (SBP) was indirectly evaluated at the beginning and end of treatment. Diastolic, systolic, and mean blood pressure were evaluated in the carotid artery of anesthetized animals, while left ventricle systolic blood pressure (LVSBP) and left ventricle derivatives (-dP/dt; +dP/dt) were evaluated in the left ventricle. An oral glucose tolerance test (GTT) was conducted. Antioxidant enzymes and calcium-handling proteins were analyzed in heart tissue by western blot. Treatment with LIRA increased the expression of antioxidant enzymes (superoxide dismutase (SOD2) and catalase). No changes were observed in the GTT, cardiac hemodynamics, blood pressure, and calcium-handling protein expression. A decrease in visceral fat depot was observed without changes in final body weight. LIRA induced an antioxidant subclinical effect in ovariectomized SHR female rats without changing glucose metabolism and cardiac blood pressure.

GLP-1 Receptor Agonists and Myocardial Perfusion: Bridging Mechanisms to Clinical Outcomes

Coronary microvascular dysfunction (CMD) is a key contributor to myocardial ischemia and adverse cardiovascular outcomes, particularly in individuals with metabolic disorders such as type 2 diabetes (T2D). While conventional therapies primarily target epicardial coronary disease, effective treatments for CMD remain limited. Glucagon-like peptide-1 receptor (GLP-1R) agonists have emerged as promising agents with cardiovascular benefits extending beyond glycemic control. Preclinical and clinical evidence suggests that GLP-1R activation enhances coronary microvascular function through mechanisms including improved endothelial function, increased nitric oxide bioavailability, attenuation of oxidative stress, and reduced vascular inflammation. Moreover, GLP-1R agonists have been shown to improve myocardial blood flow, myocardial perfusion reserve, and coronary endothelial function, particularly in high-risk populations. Despite these promising findings, inconsistencies remain across studies due to variability in patient populations, study designs, and imaging methodologies. This review summarizes current evidence on the role of GLP-1R agonists in myocardial perfusion, bridging mechanistic insights with clinical outcomes. Further large-scale, well-designed trials are needed to clarify their long-term impact on coronary microcirculation and explore their potential as targeted therapies for CMD.

High Dose of Liraglutide Impairs Renal Function in Female Hypertensive Rats

ABSTRACT

Glucagon-like peptide-1 receptor agonists exhibit beneficial cardiovascular effects. However, the renal effects of different doses of liraglutide in an essential hypertension model have not yet been investigated. Female spontaneously hypertensive rats were treated for 30 days, twice a day, with saline (control) or liraglutide at low (0.06 mg/kg) and high (LH, 0.6 mg/kg) doses. Volume intake and excretion were monitored for a period of 24 hours. In renal tissue, nitrite, nitrate, advanced protein oxidation products, collagen deposition, creatinine (Cr), urea (U), sodium, and potassium were analyzed. Liraglutide reduced body weight gain in both groups. However, in the high dose, it increased urinary volume excretion and sodium/potassium ratio. Both doses reduced the urinary U/Cr ratio and LH increased the serum U/Cr ratio. Advanced protein oxidation products were reduced only in low liraglutide. LH augmented collagen and early markers of kidney injury (blood urea nitrogen, blood urea nitrogen/Cr). LH increased nitrate, reduced nitrite, and caused an aberrant increase in glomerular filtration rate. Both doses' effects were independent of blood pressure and glycemic control. Liraglutide appears to have distinct effects on the hypertensive female kidney depending on the dose, with higher doses impairing kidney function.

Exosomes derived from umbilical cord mesenchymal stem cells promote healing of complex perianal fistulas in rats

BACKGROUND

Complex perianal fistulas, challenging to treat and prone to recurrence, often require surgical intervention that may cause fecal incontinence and lower quality of life due to large surgical wounds and potential sphincter damage. Human umbilical cord-derived MSCs (hUC-MSCs) and their exosomes (hUCMSCs-Exo) may promote wound healing.

METHODS

This study assessed the efficacy, mechanisms, and safety of these exosomes in treating complex perianal fistulas in SD rats. We established a rat model, divided rats with fistulas into the control and the exosome groups. We assessed treatment efficacy through ultrasound, clinical observations, and histopathological analysis. We also evaluated the activation of the HIF-1α/TGF-β/Smad signaling pathway via PCR and Western blot and assessed serological markers for HIF-1α and inflammatory indices through ELISA. We analyzed gut microbiota and the systemic metabolic environment via untargeted metabolomics.

RESULTS

The hUCMSCs-Exo effectively promoted healing of wound, regulated the immune balance enhanced collagen synthesis and angiogenesis in the perianal fistulas model of rats, and regulated the gut microbiota and metabolomic profiles. Results of PCR and Western blot analyses indicated that the exosomes activated HIF-1α/TGF-β/Smad signaling pathways. To the dosages tested, the 10ug/100ul concentration (medium dose) was found to be the most effective to the treatment of complex perianal fistulas.

CONCLUSIONS

The hUCMSCs-Exo significantly promoted the healing of wound in perianal fistulas of rats and demonstrated higher safety. The underlying mechanism facilitating the healing process was likely associated with the activation of the HIF-1α/TGF-β/Smad signaling pathway.

GLP-1: A Prospective Guardian for Comprehensive Myocardial Perfusion

OBJECTIVE

To investigate the role of glucagon-like peptide 1 (GLP-1) in myocardial perfusion, focusing on its effects on coronary microcirculation and cardiovascular outcomes.

METHODS

Review of foundational research and large-scale clinical trials, including Cardiovascular Outcome Trials (CVOTs), examining the cardiovascular effects of GLP-1. Systematic analysis of trial data to assess the impact of GLP-1 therapy on myocardial infarction, composite cardiovascular events, and stroke incidence.

RESULTS

GLP-1 therapy was found to significantly reduce myocardial infarction and composite cardiovascular events. Additionally, GLP-1 receptor agonists were observed to reduce stroke incidence, suggesting systemic effects on panvascular diseases. While direct protective effects on coronary microvasculature have been less studied, growing evidence supports GLP-1's role in comprehensive myocardial perfusion.

CONCLUSION

GLP-1 is a promising therapeutic agent for improving myocardial perfusion and reducing cardiovascular events. Its protection is likely associated with comprehensive improvements in myocardial perfusion, including effects on coronary microcirculation. Further research is needed to fully elucidate its mechanisms of action and potential clinical applications.

The Emerging Role of Glucagon-like Peptide-1 Receptor Agonists in the Management of Obesity-Related Heart Failure with Preserved Ejection Fraction: Benefits beyond What Scales Can Measure?

Obesity is a significant predisposing factor for heart failure with preserved ejection fraction (HFpEF). Although a substantial proportion of individuals with HFpEF also have obesity, those with obesity are under-represented in clinical trials for heart failure. In turn, current guidelines provided limited recommendations for the medical management of this patient population. Both obesity and diabetes induce a pro-inflammatory state that can contribute to endothelial dysfunction and coronary microvascular impairment, finally resulting in HFpEF. Additionally, obesity leads to increased epicardial and chest wall adiposity, which enhances ventricular interdependence. This condition is further aggravated by plasma and blood volume expansion and excessive vasoconstriction, ultimately worsening HFpEF. Despite the well-documented benefits of GLP-1 receptor agonists in subjects with diabetes, obesity, or both, their role in obesity-related HFpEF remains unclear. In light of the recently published literature, this review aims to investigate the potential mechanisms and synthesize the available clinical evidence regarding the role of GLP-1 receptor agonists in patients with obesity-related HFpEF.

Cardiovascular Protective Properties of GLP-1 Receptor Agonists: More than Just Diabetic and Weight Loss Drugs

Owing to their potent glucose-lowering efficacy and substantial weight loss effects, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are now considered part of the frontline therapeutic options to treat both type 2 diabetes mellitus and nondiabetic overweight/obesity. Stemming from successful demonstration of their cardiometabolic modulation and reduction of major adverse cardiovascular events in clinical outcome trials, GLP-1 RAs have since been validated as agents with compelling cardiovascular protective properties. Studies spanning from the bench to preclinical and large-scale randomised controlled trials have consistently corroborated the cardiovascular benefits of this pharmacological class. Most notably, there is converging evidence that they exert favourable effects on atherosclerotic ischaemic endpoints, with preclinical data indicating that they may do so by directly modifying the burden and composition of atherosclerotic plaques. This narrative review examines the underlying pharmacology and clinical evidence behind the cardiovascular benefits of GLP-1 RAs, with particular focus on atherosclerotic cardiovascular disease. It also delves into the mechanisms that underpin their putative plaque-modifying actions, addresses existing knowledge gaps and therapeutic challenges and looks to future developments in the field, including the use of combination incretin agents for diabetes and weight loss management.

Sitagliptin Ameliorates Creb5/lncRNA ENSMUST00000213271-Mediated Vascular Endothelial Dysfunction in Obese Mice

PURPOSE

Obesity is mediated by the changes in dyslipidemia, oxidative stress, and inflammation, leading to vascular endothelial dysfunction. Glucagon-like peptide-1 (GLP-1) analogues and dipeptidyl peptidase-4 inhibitors prevent the development of endothelial dysfunction. However, the underlying mechanism still remains largely unclear. Long non-coding RNAs (lncRNAs), one class of non-coding small RNAs, have been shown to exert a regulatory impact on the endothelial function in obesity. This study aimed to investigate whether the elevation of GLP-1 by a DPP-4 inhibitor sitagliptin improved vascular endothelial function by modulating lncRNAs in obese mice and to clarify the underlying molecular mechanism.

METHODS

Male C57BL/6J mice were fed a high-fat diet for 4 months to induce obesity and some obese mice were treated with sitagliptin for the last 1 month. Levels of total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and glucagon-like peptide-1 (GLP-1) in plasma were detected by ELISA. LncRNA expression profile was analyzed via microarray. Aortic relaxations were examined by myograph. Protein expressions and phosphorylations were determined using western blot. The differentially expressed lncRNAs were validated using qRT-PCR.

RESULTS

Obese mice exhibited increased levels of TC and LDL, decreased concentrations of HDL and GLP-1 in plasma, and impaired aortic endothelium-dependent relaxations; such effects could be reversed by sitagliptin. Moreover, the altered expression profile of lncRNAs in the obese mouse aortae could be modulated by sitagliptin. Consistent with microarray analysis, qRT-PCR also revealed that lncRNA ENSMUST00000213271 was up-regulated in obese mouse aortae and aortic endothelial cells (ECs), which could be down-regulated by sitagliptin. Creb5 silencing reduced lncRNA ENSMUST00000213271 in obese mouse ECs. Knockdown of either Creb5 or lncRNA ENSMUST00000213271 restored the activation of AMPK/eNOS in obese mouse ECs. Furthermore, sitagliptin also suppressed Creb5 and lncRNA ENSMUST00000213271 and increased the phosphorylations of AMPK and eNOS in obese mice.

CONCLUSION

Creb5/lncRNA ENSMUST00000213271 mediated vascular endothelial dysfunction through inhibiting AMPK/eNOS cascade in obesity. Elevation of GLP-1 by sitagliptin possibly improved endothelial function by suppressing Creb5/lncRNA ENSMUST00000213271 and subsequently restoring AMPK/eNOS activation in obese mice. This study will provide new evidence for the benefits of GLP-1 against vasculopathy in obesity.

Testicular ultrasonic microvascular density in assessing spermatogenesis and predicting successful sperm retrieval

Background

The relationship between microcirculatory disorders and testicular spermatogenesis is an area of ongoing interest among urologists. The objective of this prospective observational study was to investigate the correlation between testicular microcirculation and spermatogenesis, as well as the predictive value of ultrasonic microvascular density (UMVD) and ultrasonographic volume estimation (UVE) in successful sperm retrieval among men with non-obstructive azoospermia (NOA).

Methods

Testicular UMVD derived from Angio PLUSTM Planwave Ultrasensitive Imaging (AP), UVE were obtained. Participants were divided into 4 groups (normozoospermia; asthenozoospermia, teratozoospermia, or asthenoteratozoospermia; oligozoospermia; NOA).

Results

The study included a total of 875 participants. No significant difference was found in UMVD-mean between different semen groups (P>0.05). A total of 108 participants with NOA underwent microdissection testicular sperm extraction (micro-TESE). Participants with successful sperm retrieval (40 cases) showed significant differences in testicular UMVD and UVE compared to those with negative retrieval (68 cases) (P<0.01). We generated receiver operating characteristic (ROC) curves for UMVD and testicular UVE to differentiate participants with successful sperm retrieval from those without. The area under the curve (AUC) was 0.760 [95% confidence interval (CI): 0.658-0.849, P<0.01] for UMVD and 0.716 (95% CI: 0.609-0.822, P<0.01) for testicular UVE, respectively. The optimal cutoff value was determined based on the maximum Youden index. When UMVD was set at 28.50/cm2, its sensitivity and specificity were calculated as 57.5% and 85.3%, respectively. For testicular UVE, a cutoff value of 8.94 mL resulted in a sensitivity of 60.0% and specificity of 82.4%. Combining UMVD with testicular UVE improved diagnostic performance (AUC: 0.856, 95% CI: 0.772-0.929, P<0.01) with a sensitivity of 79.4% and specificity of 77.5%.

Conclusions

The present study demonstrates the utility of AP as a predictive tool for successful sperm retrieval prior to micro-TESE. Furthermore, the combination of testicular UMVD and UVE provides a highly valuable diagnostic approach for predicting micro-TESE success and can be routinely implemented before the procedure. A testicular UMVD exceeding 28.50/cm2 and a testicular UVE larger than 8.94 mL strongly indicate favorable outcomes in terms of sperm retrieval.

Liraglutide Protects Cardiomyocytes against Isoprenaline-Induced Apoptosis in Experimental Takotsubo Syndrome

Takotsubo syndrome (TTS) is a stress-induced cardiomyopathy, characterized by an increased concentration of catecholamines, free radicals, and inflammatory cytokines, endothelial dysfunction, and increased apoptotic activity. High doses of isoprenaline are used in animal models to induce Takotsubo (TT)-like myocardial injury. The aim of the study was to investigate the antiapoptotic effects of liraglutide in experimental TTS and its role in the NF-κB pathway. Wistar rats were pretreated with liraglutide for 10 days, and on days 9 and 10, TT-like myocardial injury was induced with isoprenaline. After the sacrifice on day 11, hearts were isolated for histopathological and immunohistochemical analysis. Liraglutide reduced isoprenaline-induced cardiomyocyte apoptosis by decreasing cleaved caspase-3 (CC3), BCL-2-associated X protein (BAX), and NF-κB and increasing B-cell lymphoma/leukemia-2 (BCL-2). An increase in NF-κB in isoprenaline-treated rats was in positive correlation with proapoptotic markers (BAX and CC3) and in negative correlation with antiapoptotic marker BCL-2. Liraglutide increased BCL-2 and decreased NF-κB, BAX, and CC3, preserving the same correlations of NF-κB to apoptotic markers. It is concluded that liraglutide protects cardiomyocytes against isoprenaline-induced apoptosis in experimental TT-like myocardial injury through downregulation of the NF-κB pathway.

GLP-1 receptor agonists and myocardial metabolism in atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Many medical conditions, including hypertension, diabetes, obesity, sleep apnea, and heart failure (HF), increase the risk for AF. Cardiomyocytes have unique metabolic characteristics to maintain adenosine triphosphate production. Significant changes occur in myocardial metabolism in AF. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been used to control blood glucose fluctuations and weight in the treatment of type 2 diabetes mellitus (T2DM) and obesity. GLP-1RAs have also been shown to reduce oxidative stress, inflammation, autonomic nervous system modulation, and mitochondrial function. This article reviews the changes in metabolic characteristics in cardiomyocytes in AF. Although the clinical trial outcomes are unsatisfactory, the findings demonstrate that GLP-1 RAs can improve myocardial metabolism in the presence of various risk factors, lowering the incidence of AF.

Peptides Are Cardioprotective Drugs of the Future: The Receptor and Signaling Mechanisms of the Cardioprotective Effect of Glucagon-like Peptide-1 Receptor Agonists

The high mortality rate among patients with acute myocardial infarction (AMI) is one of the main problems of modern cardiology. It is quite obvious that there is an urgent need to create more effective drugs for the treatment of AMI than those currently used in the clinic. Such drugs could be enzyme-resistant peptide analogs of glucagon-like peptide-1 (GLP-1). GLP-1 receptor (GLP1R) agonists can prevent ischemia/reperfusion (I/R) cardiac injury. In addition, chronic administration of GLP1R agonists can alleviate the development of adverse cardiac remodeling in myocardial infarction, hypertension, and diabetes mellitus. GLP1R agonists can protect the heart against oxidative stress and reduce proinflammatory cytokine (IL-1β, TNF-α, IL-6, and MCP-1) expression in the myocardium. GLP1R stimulation inhibits apoptosis, necroptosis, pyroptosis, and ferroptosis of cardiomyocytes. The activation of the GLP1R augments autophagy and mitophagy in the myocardium. GLP1R agonists downregulate reactive species generation through the activation of Epac and the GLP1R/PI3K/Akt/survivin pathway. The GLP1R, kinases (PKCε, PKA, Akt, AMPK, PI3K, ERK1/2, mTOR, GSK-3β, PKG, MEK1/2, and MKK3), enzymes (HO-1 and eNOS), transcription factors (STAT3, CREB, Nrf2, and FoxO3), KATP channel opening, and MPT pore closing are involved in the cardioprotective effect of GLP1R agonists.

Unlocking the miRNA-34a-5p/TGF-β and HMGB1/PI3K/Akt/mTOR crosstalk participate in the enhanced cardiac protection of liraglutide against isoproterenol-induced acute myocardial injury rat model

Liraglutide (LIRA), a drug used to treat type 2 diabetes mellitus that belongs to the glucagon-like peptide-1 class, has recently drawn attention for its potential cardioprotective properties because of its anti-oxidative and anti-inflammatory properties. This current investigation was designed to assess the impact of LIRA on myocardial injury induced by isoproterenol (ISO). The experiment included 24 male Wistar rats in total, and they were divided into four groups: Control, LIRA (200 µg/kg/12 hrs., S.C.), ISO (85 mg/kg, S.C.), and ISO + LIRA. To assess the results, various biochemical and histopathological analyses were carried out. The findings showed elevated serum enzyme levels, a sign of cardiac injury. ISO-treated rats showed an upregulation of oxidative stress and inflammatory biomarkers like MDA, MPO, nitrites, NADPH oxidase, TNF-α, IL-1β, IL-6, 8-Hydroxyguanosine (8-OHdG), and TGF-β, as well as altered gene expressions like TLR-1 and miRNA-34a-5p. According to western blotting analysis, protein levels of AKT, PI3K, and mTOR were obviously enhanced. Additionally, ISO-treated samples showed altered tissue morphology, elevated caspase 3, and decreased Bcl2 concentrations. The levels of these dysregulated parameters were significantly normalized by LIRA therapy, demonstrating its cardioprotective function against ISO-induced myocardial injury in rats. This protective mechanism was linked to anti-inflammatory properties, redox balance restoration, and modulation of the miRNA-34a-5p/TGF-β pathway.

Effect of Liraglutide on Osteoporosis in a Rat Model of Type 2 Diabetes Mellitus: A Histological, Immunohistochemical, and Biochemical Study

Diabetic osteoporosis (DOP) is a diabetic complication associated with a significant disability rate. Liraglutide, a glucagon-like peptide-1 receptor agonist, is a promising and innovative drug for type 2 diabetes mellitus (T2DM), with potential therapeutic implications for bone disorders. This investigation examined the impact of liraglutide on osteoporosis in rats with T2DM and studied the influence of vitamin D receptor Bsm1 polymorphism on liraglutide-induced outcomes. Thirty rats were divided into control, T2DM induced by a combination of a high-fat diet and 25 mg/kg streptozotocin, and T2DM-liraglutide (T2DM treated with 0.4 mg/kg/day liraglutide) groups. After 8 weeks of liraglutide treatment, femurs and blood samples were obtained from all rats for subsequent investigations. Diabetes induced a remarkable rise in the serum levels of receptor activator of nuclear factor kappa B ligand (RANKL) and C-telopeptide of type I collagen (CTX-1) associated with a remarkable decline in osteocalcin and osteoprotegerin (OPG). Impaired bone architecture was also demonstrated by light and scanning electron microscopic study. The immune expression of OPG was down-regulated, while RANKL was up-regulated. Interestingly, the administration of liraglutide ameliorated the previous changes induced by diabetes mellitus. In conclusion, liraglutide can prevent DOP, mostly due to liraglutide's ability to increase bone growth, while inhibiting bone resorption.

Microvascular Dysfunction in Obesity-Hypertension

PURPOSE OF REVIEW

This review aims to explore the role of microvascular dysfunction in obesity-hypertension, discuss the effects obesity has on renal microvasculature, review the current methods for assessing microvascular dysfunction and available therapeutic options, and identify critical areas for further research.

RECENT FINDINGS

There is a strong association between obesity and hypertension. However, the pathophysiology of obesity-hypertension is not clear. Microvascular dysfunction has been linked to hypertension and obesity and could be an important mediator of obesity-related hypertension. Newer therapies for hypertension and obesity could have ameliorating effects on microvascular dysfunction, including GLP-1 agonists and SGLT-2 inhibitors. There is still much progress to be made in our understanding of the complex interplay between obesity, hypertension, and microvascular dysfunction. Continued efforts to understand microvascular dysfunction and its role in obesity-hypertension are crucial to develop precision therapy to target obesity-hypertension.

Current challenges in the treatment of cardiac fibrosis: Recent insights into the sex-specific differences of glucose-lowering therapies on the diabetic heart: IUPHAR Review 33

A significant cardiac complication of diabetes is cardiomyopathy, a form of ventricular dysfunction that develops independently of coronary artery disease, hypertension and valvular diseases, which may subsequently lead to heart failure. Several structural features underlie the development of diabetic cardiomyopathy and eventual diabetes-induced heart failure. Pathological cardiac fibrosis (interstitial and perivascular), in addition to capillary rarefaction and myocardial apoptosis, are particularly noteworthy. Sex differences in the incidence, development and presentation of diabetes, heart failure and interstitial myocardial fibrosis have been identified. Nevertheless, therapeutics specifically targeting diabetes-associated cardiac fibrosis remain lacking and treatment approaches remain the same regardless of patient sex or the co-morbidities that patients may present. This review addresses the observed anti-fibrotic effects of newer glucose-lowering therapies and traditional cardiovascular disease treatments, in the diabetic myocardium (from both preclinical and clinical contexts). Furthermore, any known sex differences in these treatment effects are also explored. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Inflammatory atherosclerotic plaque identification by SPECT/CT imaging of LFA-1 using [111In] In-DANBIRT in a novel dyslipidemic rat model

INTRODUCTION

Atherosclerosis is prevalent globally, closely associated with dyslipidemia and other metabolic dysfunction. Early diagnosis of atherosclerosis is challenging due to limited diagnostic capabilities that need to be expanded with animal models with enhanced vascular biology like rats. Our previous research showed [111In] In-DANBIRT has potential as a diagnostic tool for detecting atherosclerosis in mice. The primary aim of the present study is to evaluate [111In] In-DANBIRT in a novel atherosclerotic rat with early- and late-stage atherosclerosis and metabolic disease.

METHODS

We characterized metabolic and body composition differences in these novel dyslipidemic rats under different diets using serum chemistry and dual-energy X-ray absorptiometry (DEXA) scan, respectively. We performed 1-h post-injection in vivo molecular imaging of ApoE knockout, lean Zucker (LZ) male rats at baseline and followed them into 10 weeks of either normal or high-fat/cholesterol diet implementation (22 weeks of age).

RESULTS

We identified significant differences in body composition and metabolic changes in ApoE knockout rats compared to ApoE wildtype rats. Our findings indicate an increased uptake of [111In] In-DANBIRT in ApoE knockout, lean Zucker (LZ) rats, particularly in the descending aorta, a location where early-stage atherosclerosis is commonly found. Our findings, however, also revealed that the ApoE knockout, Zucker diabetic fatty (ZDF) model has high mortality rate, which may be attributed to alterations of critical enzymes involved in regulating metabolism and liver function.

CONCLUSION

Our results are highly encouraging as they demonstrated the potential of [111In] In-DANBIRT to detect early-stage atherosclerosis in rats that might otherwise go unnoticed by other methods, showcasing the high sensitivity of [111In] In-DANBIRT. Our future studies will aim to establish a viable T2D atherosclerosis model in rats with more advanced stages of the disease to further demonstrate the reliability of [111In] In-DANBIRT as a diagnostic tool for patients in all stages of atherosclerosis.

Searching for Effective Treatments in HFpEF: Implications for Modeling the Disease in Rodents

BACKGROUND

While the prevalence of heart failure with preserved ejection fraction (HFpEF) has increased over the last two decades, there still remains a lack of effective treatment. A key therapeutic challenge is posed by the absence of animal models that accurately replicate the complexities of HFpEF. The present review summarizes the effects of a wide spectrum of therapeutic agents on HF.

METHODS

Two online databases were searched for studies; in total, 194 experimental protocols were analyzed following the PRISMA protocol.

RESULTS

A diverse range of models has been proposed for studying therapeutic interventions for HFpEF, with most being based on pressure overload and systemic hypertension. They have been used to evaluate more than 150 different substances including ARNIs, ARBs, HMGR inhibitors, SGLT-2 inhibitors and incretins. Existing preclinical studies have primarily focused on LV diastolic performance, and this has been significantly improved by a wide spectrum of candidate therapeutic agents. Few experiments have investigated the normalization of pulmonary congestion, exercise capacity, animal mortality, or certain molecular hallmarks of heart disease.

CONCLUSIONS

The development of comprehensive preclinical HFpEF models, with multi-organ system phenotyping and physiologic stress-based functional testing, is needed for more successful translation of preclinical research to clinical trials.

The effect of exenatide (a GLP-1 analogue) and sitagliptin (a DPP-4 inhibitor) on asymmetric dimethylarginine (ADMA) metabolism and selected biomarkers of cardiac fibrosis in rats with fructose-induced metabolic syndrome

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is a risk factor for endothelial dysfunction, a common pathophysiological denominator for both atherogenesis and cardiac fibrosis. We aimed to investigate whether the cardioprotective and antifibrotic effects of incretin drugs, exenatide and sitagliptin, may be associated with their ability to affect circulating and cardiac ADMA metabolism. Normal and fructose-fed rats were treated with sitagliptin (5.0/10 mg/kg) or exenatide (5/10 µg/kg) for 4 weeks. The following methods were used: LC-MS/MS, ELISA, Real-Time-PCR, colorimetry, IHC and H&E staining, PCA and OPLS-DA projections. Eight-week fructose feeding resulted in an increase in plasma ADMA and a decrease in NO concentration. Exenatide administration into fructose-fed rats reduced the plasma ADMA level and increased NO level. In the heart of these animals exenatide administration increased NO and PRMT1 level, reduced TGF-ß1, α-SMA levels and COL1A1 expression. In the exenatide treated rats renal DDAH activity positively correlated with plasma NO level and negatively with plasma ADMA level and cardiac α-SMA concentration. Sitagliptin treatment of fructose-fed rats increased plasma NO concentration, reduced circulating SDMA level, increased renal DDAH activity and reduced myocardial DDAH activity. Both drugs attenuated the myocardial immunoexpression of Smad2/3/P and perivascular fibrosis. In the metabolic syndrome condition both sitagliptin and exenatide positively modulated cardiac fibrotic remodeling and circulating level of endogenous NOS inhibitors but had no effects on ADMA levels in the myocardium.

Liraglutide ameliorates diabetic-induced testicular dysfunction in male rats: role of GLP-1/Kiss1/GnRH and TGF-β/Smad signaling pathways

Introduction: Glucagon-like peptide -1 (GLP-1) is released by intestinal cells to stimulate glucose-dependent insulin release from the pancreas. GLP-1 has been linked to ameliorating obesity and/or diabetic complications as well as controlling reproductive function. Liraglutide is a GLP-1 receptor agonist (GLP-1RA) with 97% homology with GLP-1. The main objective of this study was to investigate the ameliorative role of liraglutide in diabetic-induced reproductive dysfunction in male rats. Methods: Rats were randomly allocated into 3 groups; a control group, a diabetic group, and a liraglutide-treated diabetic group. Results: In the diabetic group, a significant increase in BMI, FBG, HbA1c, HOMA-IR, TC, TAG, LDL, IL6, TNFα, and MDA, as well as decreased serum insulin, HDL, GSH, total testosterone, LH, and FSH, were shown compared to the control group. Furthermore, A significant downregulation in relative hypothalamic gene expression of GLP-1R, PPAR-α, PGC-1α, kiss, kiss1R, leptin, leptin R, GnRH GLP-1R, testicular PGC-1α, PPARα, kiss1, kiss1R, STAR, CYP17A1, HSD17B3, CYP19A, CYP11A1, and Smad7, as well as upregulation in hypothalamic GnIH and testicular TGF- β and Smad2 expression, were noticed compared to the control group. Liraglutide treatment significantly improved such functional and structural reproductive disturbance in diabetic rats. Conclusion: GLP-1RAs ameliorated the deleterious effects of diabetes on reproductive function by targeting GLP-1/leptin/kiss1/GnRH, steroidogenesis, and TGF- β/Smad pathways.

Coronary Microvascular Dysfunction in Diabetes Mellitus: Pathogenetic Mechanisms and Potential Therapeutic Options

Diabetic patients are frequently affected by coronary microvascular dysfunction (CMD), a condition consisting of a combination of altered vasomotion and long-term structural change to coronary arterioles leading to impaired regulation of blood flow in response to changing cardiomyocyte oxygen requirements. The pathogenesis of this microvascular complication is complex and not completely known, involving several alterations among which hyperglycemia and insulin resistance play particularly central roles leading to oxidative stress, inflammatory activation and altered barrier function of endothelium. CMD significantly contributes to cardiac events such as angina or infarction without obstructive coronary artery disease, as well as heart failure, especially the phenotype associated with preserved ejection fraction, which greatly impact cardiovascular (CV) prognosis. To date, no treatments specifically target this vascular damage, but recent experimental studies and some clinical investigations have produced data in favor of potential beneficial effects on coronary micro vessels caused by two classes of glucose-lowering drugs: glucagon-like peptide 1 (GLP-1)-based therapy and inhibitors of sodium-glucose cotransporter-2 (SGLT2). The purpose of this review is to describe pathophysiological mechanisms, clinical manifestations of CMD with particular reference to diabetes, and to summarize the protective effects of antidiabetic drugs on the myocardial microvascular compartment.

Ameliorative Impact of Liraglutide on Chronic Intermittent Hypoxia-Induced Atrial Remodeling

Atrial fibrillation (AF) is the most frequent form of clinical cardiac arrhythmias. Previous evidence proved that atrial anatomical remodeling (AAR) and atrial electrical remodeling (AER) are crucial for the progression and maintenance of AF. This study is aimed at investigating the impact of the glucagon-like peptide-1 (GLP-1) receptor agonist, Liraglutide (Lir), on atrial remodeling (AR) mouse model induced by chronic intermittent hypoxia (CIH). C57BL/6 mice were categorized randomly into the control, Lir, CIH, and CIH+Lir groups. CIH was performed in CIH and CIH+Lir groups for 12 weeks. Lir (0.3 mg/kg/day, s.c) was administered to the Lir and CIH+Lir groups for four weeks, beginning from the ninth week of CIH. Meanwhile, echocardiography and right atrial endocardial electrophysiology via jugular vein, as well as induction rate and duration of AF, were evaluated. Masson and Sirius red staining assays were utilized to assess the extent of fibrosis in the atrial tissue of the mice. Immunohistochemical staining, RT-qPCR, and Western blotting were performed to evaluate the marker levels of AAR and AER and the expression of genes and proteins of the miR-21/PTEN/PI3K/AKT signaling pathway, respectively. ELISA was also performed to evaluate the changes of serum inflammatory factor levels. The CIH group exhibited significant AR, increased atrial fibrosis, and a higher incidence rate of AF compared to the control group. Lir could significantly downregulate the protein expression level in the PI3K/p-AKT pathway and upregulated that of phosphatase and tensin homolog deleted on chromosome ten (PTEN). Moreover, Lir downregulated the expression of miR-21. However, the protein expressions of CACNA1C and KCNA5 in atrial tissue were not changed significantly. In addition, Lir significantly attenuated the levels of markers of inflammation (TNF-α and IL-6) in the serum. In the mouse model of CIH, Lir treatment could ameliorate AR by the miR-21/PTEN/PI3K/AKT signaling pathway and modulation of inflammatory responses.

GLP-1 Receptor Agonists and Coronary Arteries: From Mechanisms to Events

Objective: Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) lower plasma glucose through effects on insulin and glucagon secretion and by decelerating gastric emptying. GLP-1 RAs have many beneficial effects beyond glycemic control, including a protective role on the cardiovascular system. However, underlying mechanisms linking GLP-1 RAs with coronary artery disease are complex and not fully elucidated. In this mini-review, we discuss these mechanisms and subsequent clinical events.

Data Sources: We searched PubMed and Google Scholar for evidence on GLP-1 RAs and coronary events. We did not apply restrictions on article type. We reviewed publications for clinical relevance.

Synopsis of Content: In the first part, we review the current evidence concerning the role of GLP-1 RAs on potential mechanisms underlying the development of coronary events. Specifically, we discuss the role of GLP-1 RAs on atherosclerosis and vasospasms of epicardial coronary arteries, as well as structural/functional changes of coronary microvasculature. In the second part, we summarize the clinical evidence on the impact of GLP-1 RAs in the prevention of acute and chronic coronary syndromes and coronary revascularization. We conclude by discussing existing gaps in the literature and proposing directions for future research.

Inflammatory Mechanisms Contributing to Endothelial Dysfunction

Maintenance of endothelial cell integrity is an important component of human health and disease since the endothelium can perform various functions including regulation of vascular tone, control of hemostasis and thrombosis, cellular adhesion, smooth muscle cell proliferation, and vascular inflammation. Endothelial dysfunction is encompassed by complex pathophysiology that is based on endothelial nitric oxide synthase uncoupling and endothelial activation following stimulation from various inflammatory mediators (molecular patterns, oxidized lipoproteins, cytokines). The downstream signaling via nuclear factor-κB leads to overexpression of adhesion molecules, selectins, and chemokines that facilitate leukocyte adhesion, rolling, and transmigration to the subendothelial space. Moreover, oscillatory shear stress leads to pro-inflammatory endothelial activation with increased monocyte adhesion and endothelial cell apoptosis, an effect that is dependent on multiple pathways and flow-sensitive microRNA regulation. Moreover, the role of neutrophil extracellular traps and NLRP3 inflammasome as inflammatory mechanisms contributing to endothelial dysfunction has recently been unveiled and is under further investigation. Consequently, and following their activation, injured endothelial cells release inflammatory mediators and enter a pro-thrombotic state through activation of coagulation pathways, downregulation of thrombomodulin, and an increase in platelet adhesion and aggregation owing to the action of von-Willebrand factor, ultimately promoting atherosclerosis progression.

Cardioprotective potential of indol-3-carbinol against high salt induced myocardial stress and hypertrophy in Sprague dawley rats besides molecular docking on muscarinic receptor-2

The vegetative chemical constituent, indol-3-carbinol (I-3-C) studied for its cardioprotective potential in male Sprague dawley rats. The I-3-C at 20 mg/Kg b.w, p.o significantly (p < 0.001) attenuated the high salt induced hypertrophy and produced antihypertensive effect (p < 0.001) as similar to losartan. Further, it significantly reduced the levels of C-reactive protein (p < 0.05), creatinine kinases isoenzyme (p < 0.01), serum lactate dehydrogenase (p < 0.05), myeloperoxidase (p < 0.01) and hydroxyproline (p < 0.01), subsequently increased the nitric oxide level (p < 0.05). The carotid ligation for vascular reactivity against vasopressors revealed a lesser magnitude of change (p < 0.05) in invasive blood pressure for I-3-C, compared to high salt treated animals (p < 0.001). In histology of heart tissue also supported the cardioprotective effect of I-3-C. In silico molecular docking of I-3-C on muscarinic receptor-2 showed the amino acid interaction as similar to acetylcholine.

β-blockade prevents coronary macro- and microvascular dysfunction induced by a high salt diet and insulin resistance in the Goto-Kakizaki rat

A high salt intake exacerbates insulin resistance, evoking hypertension due to systemic perivascular inflammation, oxidative-nitrosative stress and endothelial dysfunction. Angiotensin-converting enzyme inhibitor (ACEi) and angiotensin receptor blockers (ARBs) have been shown to abolish inflammation and redox stress but only partially restore endothelial function in mesenteric vessels. We investigated whether sympatho-adrenal overactivation evokes coronary vascular dysfunction when a high salt intake is combined with insulin resistance in male Goto-Kakizaki (GK) and Wistar rats treated with two different classes of β-blocker or vehicle, utilising synchrotron-based microangiography in vivo. Further, we examined if chronic carvedilol (CAR) treatment preserves nitric oxide (NO)-mediated coronary dilation more than metoprolol (MET). A high salt diet (6% NaCl w/w) exacerbated coronary microvessel endothelial dysfunction and NO-resistance in vehicle-treated GK rats while Wistar rats showed modest impairment. Microvascular dysfunction was associated with elevated expression of myocardial endothelin, inducible NO synthase (NOS) protein and 3-nitrotyrosine (3-NT). Both CAR and MET reduced basal coronary perfusion but restored microvessel endothelium-dependent and -independent dilation indicating a role for sympatho-adrenal overactivation in vehicle-treated rats. While MET treatment reduced myocardial nitrates, only MET treatment completely restored microvessel dilation to dobutamine (DOB) stimulation in the absence of NO and prostanoids (combined inhibition), indicating that MET restored the coronary flow reserve attributable to endothelium-derived hyperpolarisation (EDH). In conclusion, sympatho-adrenal overactivation caused by high salt intake and insulin resistance evoked coronary microvessel endothelial dysfunction and diminished NO sensitivity, which were restored by MET and CAR treatment in spite of ongoing inflammation and oxidative-nitrosative stress presumably caused by uninhibited renin-angiotensin-aldosterone system (RAAS) overactivation.

Empagliflozin and Liraglutide Differentially Modulate Cardiac Metabolism in Diabetic Cardiomyopathy in Rats

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2is) are antihyperglycemic agents with cardioprotective properties against diabetic cardiomyopathy (DCM). However, the distinctive mechanisms underlying GLP-1RAs and SGLT2is in DCM are not fully elucidated. The purpose of this study was to investigate the impacts of GLP1RAs and/or SGLT2is on myocardial energy metabolism, cardiac function, and apoptosis signaling in DCM. Biochemistry and echocardiograms were studied before and after treatment with empagliflozin (10 mg/kg/day, oral gavage), and/or liraglutide (200 μg/kg every 12 h, subcutaneously) for 4 weeks in male Wistar rats with streptozotocin (65 mg/kg intraperitoneally)-induced diabetes. Cardiac fibrosis, apoptosis, and protein expression of metabolic and inflammatory signaling molecules were evaluated by histopathology and Western blotting in ventricular cardiomyocytes of different groups. Empagliflozin and liraglutide normalized myocardial dysfunction in diabetic rats. Upregulation of phosphorylated-acetyl coenzyme A carboxylase, carnitine palmitoyltransferase 1β, cluster of differentiation 36, and peroxisome proliferator-activated receptor-gamma coactivator, and downregulation of glucose transporter 4, the ratio of phosphorylated adenosine monophosphate-activated protein kinase α2 to adenosine monophosphate-activated protein kinase α2, and the ratio of phosphorylated protein kinase B to protein kinase B in diabetic cardiomyocytes were restored by treatment with empagliflozin or liraglutide. Nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3, interleukin-1β, tumor necrosis factor-α, and cleaved caspase-1 were significantly downregulated in empagliflozin-treated and liraglutide-treated diabetic rats. Both empagliflozin-treated and liraglutide-treated diabetic rats exhibited attenuated myocardial fibrosis and apoptosis. Empagliflozin modulated fatty acid and glucose metabolism, while liraglutide regulated inflammation and apoptosis in DCM. The better effects of combined treatment with GLP-1RAs and SGLT2is may lead to a potential strategy targeting DCM.

Taxifolin improves disorders of glucose metabolism and water-salt metabolism in kidney via PI3K/AKT signaling pathway in metabolic syndrome rats

AIMS

Our study was designed to explore the function and mechanism of taxifolin on glucose metabolism and water-salt metabolism in kidney with metabolic syndrome (MS) rats.

MAIN METHODS

Spontaneous hypertensive rats were induced by fructose to establish MS model. Systolic blood pressure (SBP) and homeostasis model assessment of insulin resistance (HOMA-IR) were measured after 7 weeks of continuous administration with taxifolin. Kidney injury indices and histopathological evaluation were done. The apoptosis rate of primary kidney cells was detected by flow cytometry. Insulin signaling pathway related proteins and renal glucose transport-related proteins were detected by western blotting. We assessed the effects of taxifolin on sodium water retention and renin-angiotensin-aldosterone system (RAAS) in MS rats. We examined not only changes in urine volume, osmotic pressure, urinary sodium and urinary chloride excretion, but also the effects on NA⁺/K⁺-ATPase and RAAS indicators. We also detected changes in inflammatory factors by immunohistochemical staining and immunofluorescence. In vitro experiment, high glucose and salt stimulated NRK-52E cells. By adding the PI3K inhibitor (wortmannin) to inhibit the PI3K, the effects of inhibiting the PI3K/AKT signaling pathway on glucose metabolism, water-sodium retention and inflammatory response were discussed.

KEY FINDINGS

Taxifolin effectively reversed SBP, HOMA-IR, the kidney indices and abnormal histopathological changes induced by MS. Besides, taxifolin called back the protein associated with the downstream glucose metabolism pathway of PI3K/AKT. It also inhibited overactivation of RAAS and inflammatory response. In vitro experiments have demonstrated that the PI3K/AKT signaling pathway plays an important role in this process.

SIGNIFICANCE

Taxifolin can improve homeostasis of glucose, inhibit overactivation of RAAS and reduce inflammatory response by PI3K/AKT signaling pathway.

Liraglutide, a glucagon-like peptide-1 receptor agonist, suppresses osteoclastogenesis through the inhibition of NF-κB and MAPK pathways via GLP-1R

Bone disorders such as osteoporosis, Paget's disease of the bone, osteogenesis imperfecta, are caused by the uncoordinated action of osteoclasts and osteoblasts. Inhibiting osteoclastogenesis and suppressing the resorptive function of osteoclasts might become a gold standard strategy for treating this kind of disease. Glucagon-like peptide-1 (GLP-1) and its receptor agonist have been reported to have protective effects on bone. Little is known about the effect of GLP-1 on osteoclasts. Therefore, we investigated the effects of liraglutide, a GLP-1 receptor agonist, on murine bone marrow-derived macrophage (BMM) and RAW264.7 preosteoclast differentiation and explored the potential cellular basis of its action. In this study, we confirmed the presence of GLP-1 receptor (GLP-1R) on BMMs and RAW264.7 cells and demonstrated that GLP-1R might be important for osteoclastogenesis by increasing the expression of osteoclastogenic biomarkers after GLP-1R knockdown. In addition, we found that liraglutide treatment of both BMMs and RAW264.7 cells could inhibit osteoclast formation and bone resorption. Mechanistically, Western blotting and RT-PCR showed that liraglutide inhibited the NF-κB and MAPK signalling pathways, ultimately inhibiting the expression of nuclear factor of activated T cells (NFATc1). In addition, knocking down GLP-1R reversed the inhibitory effect of liraglutide on NF-κB/MAPK-NFATc1. Overall, these results indicated a potential therapeutic effect of liraglutide on bone disorders.