Background and Purpose The small molecule BGP‐15 has been reported to alleviate symptoms of heart failure and improve muscle function in murine models. Here, we investigated the acute and chronic effects of BGP‐15 in a rabbit model of atherosclerotic cardiomyopathy. Experimental Approach Rabbits were maintained on standard chow (control) or atherogenic diet (hypercholesterolemic) for 16 weeks. BGP‐15 was administered intravenously (once) or orally (for 16 weeks), to assess acute and chronic effects. Cardiac function was evaluated by echocardiography, endothelium‐dependent vasorelaxation was assessed and key molecules in the protein kinase G (PKG) pathway were examined by enzyme‐linked immunosorbent assay (ELISA) and western blot. Passive force generation was investigated in skinned cardiomyocytes. Key Results Both acute and chronic BGP‐15 treatments improved the diastolic performance of the diseased heart. However, vasorelaxation and serum lipid markers were unaffected. Myocardial cyclic guanosine monophosphate (cGMP) levels were elevated in the BGP‐15‐treated group, along with preserved PKG activity and increased phospholamban Ser16‐phosphorylation. PDE5 expression decreased in the BGP‐15‐treated group and PDE1 was inhibited. Cardiomyocyte passive tension reduced in BGP‐15‐treated rabbits, the ratio of titin N2BA/N2B isoforms increased and PKG‐dependent N2B‐titin phosphorylation elevated. Conclusions and Implications BGP‐15 treatment improves diastolic function, reduces cardiomyocyte stiffness and restores titin compliance in a rabbit model of atherosclerotic cardiomyopathy by increasing the activity of the cGMP‐PKG pathway. As BGP‐15 has been proven to be safe, it may be clinically useful in the treatment of diastolic dysfunction.
Inflammatory Bowel Disease (IBD) is an autoimmune ailment of the gastrointestinal (GI) tract, which is characterized by enhanced activation of proinflammatory cytokines. It is suggested that the sigma-1 receptor (σ1R) confers anti-inflammatory effects. As the exact pathogenesis of IBD is still unknown and treatment options are limited, we aimed to investigate the effects of σ1R in 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced experimental colitis. To this end, male Wistar-Harlan rats were used to model colitic inflammation through the administration of TNBS. To investigate the effects of σ1R, Fluvoxamine (FLV, σ1R agonist) and BD1063 (σ1R antagonist) were applied via intracolonic administration to the animals once a day for three days. Our radioligand binding studies indicated the existence of σ1Rs as [3H](+)-pentazocine binding sites, and FLV treatment increased the reduced σ1R maximum binding capacity in TNBS-induced colitis. Furthermore, FLV significantly attenuated the colonic damage, the effect of which was abolished by the administration of BD1063. Additionally, FLV potentially increased the expression of ubiquitin C-terminal hydrolase ligase-1 (UCHL-1) and the levels of endothelial nitric oxide synthase (eNOS), and decreased the levels of interleukin-6 (IL-6) and inducible NOS (iNOS) expression. In summary, our study offers evidence for the anti-inflammatory potential of FLV and σ1R in experimental colitis, and our results present a promising approach to the development of new σ1R-targeted treatment options against IBD.
Advanced age is an independent risk factor for cardiovascular diseases, which might be further exacerbated by estrogen deficiency. Hormone replacement therapy (HRT) decreases cardiovascular risks and events in postmenopausal women; however, its effects are not fully elucidated in older individuals. Thus, the aim of our study is to examine the impact of HRT on oxidant/antioxidant homeostasis and cardiac remodeling. In our experiment, control (fertile) and aging (~20‐month‐old) female Wistar rats were used. Aging rats were further divided into estrogen‐ (E 2 , 0.1 mg/kg/day per os ) or raloxifene‐ (RAL, 1.0 mg/kg/day per os ) treated subgroups. After 2 weeks of treatment, cardiac heme oxygenase (HO) activity, total glutathione (GSH) content, matrix metalloproteinase‐2 (MMP‐2) activity, and the concentrations of collagen type I and tissue inhibitor of metalloproteinase (TIMP‐2), as well as the infarct size, were determined. The aging process significantly decreased the antioxidant HO activity and GSH content, altered the MMP‐2/TIMP‐2 signaling, and resulted in an excessive collagen accumulation, which culminated in cardiovascular injury. However, 2 weeks of either E 2 or RAL treatment enhanced the antioxidant defense mechanisms and attenuated cardiac remodeling related to aging. Our findings clearly show that 2‐week‐long HRT is a potential intervention to bias successful cardiovascular aging via reducing oxidative damage and cardiovascular dysfunction.
The hypothalamic⁻pituitary axis by secreting neuropeptides plays a key role in metabolic homeostasis. In light of the metabolic regulation, oxytocin is a potential neuropeptide for therapies against obesity and related disorders. The aim of our study is to measure ghrelin-induced oxytocin secretion in rats and to detect the changes after administration of ghrelin antagonist.Ghrelin was administrated centrally (intracerebroventricular, i.c.v., 1.0, 10.0, and 100.0 pmol) or systemically (intravenous, i.v., 1.0, and 10.0 nmol). [d-Lys³]-GHRP-6 ghrelin antagonist was injected 15 min before ghrelin injection in a dose of 10.0 pmol i.c.v. and 10.0 nmol i.v.Either i.c.v. or i.v. administration of ghrelin dose-dependently increased the plasma oxytocin concentration. Following pretreatment with the ghrelin antagonist [d-Lys³]-GHRP-6, the high plasma oxytocin level induced by ghrelin was significantly reduced.The results indicate that the release of oxytocin is influenced directly by the ghrelin system. Examination of the mechanism of ghrelin-induced oxytocin secretion is a new horizon for potential therapeutic options.
Dipeptidyl peptidase-4 (DPP-4) inhibitors are a class of oral anti-diabetic drugs, implicated in pleiotropic secondary cardioprotective effects. The aim of the study was to unveil the unknown and possible cardioprotective targets that can be exerted by sitagliptin (Sitg) against ischemia-reperfusion (I/R) injury. Male wistar rats received 2 weeks' Sitg oral treatment of different doses (25, 50, 100, and 150 mg/kg/day), or saline as a Control. Hearts were then isolated and subjected to two different I/R injury protocols: 10 min perfusion, 45 min regional ischemia, and 120 min reperfusion for infarct size (IS) measurement, or: 10 min perfusion, 45 min regional ischemia and 10 min reperfusion for biochemical analysis: nitric oxide synthases (NOSs) and DPP-4 activity, glucagon-like peptide-1 (GLP-1), Calcium, transient receptor potential vanilloid (TRPV)-1 and calcitonin gene-related peptide (CGRP) levels, transient receptor potential canonical (TRPC)-1 and e-NOS protein expression. NOS inhibitor (L-NAME) and TRPV-1 inhibitor (Capsazepine) were utilized to confirm the implication of both signaling mechanisms in DPP-4 inhibition-induced at the level of IS. Findings show that Sitg (50 mg) resulted in significant decrease in IS and DPP-4 activity, and significant increase in GLP-1, NOS activity, e-NOS expression, TRPV-1 level and TRPC-1 expression, compared to controls. Results of CGRP are in line with TRPV-1, as a downstream regulatory effect. NOS system and transient receptor potential (TRP) channels can contribute to DPP-4 inhibition-mediated cardioprotection against I/R injury using Sitagliptin.
Estrogen deficiency is one of the main causes of age-associated diseases in the cardiovascular system. Female Wistar rats were divided into four experimental groups: pharmacologically ovariectomized, surgically ovariectomized, and 24-month-old intact aging animals were compared with a control group. The activity and expression of heme oxygenases (HO) in the cardiac left ventricle, the concentrations of cardiac interleukin-6 (IL-6) and tumor necrosis factor-α(TNF-α), the myeloperoxidase (MPO) activity in the cardiac left ventricle, and the effects of heme oxygenase blockade (by 24-hour and 1-hour pretreatment with tin-protoporphyrin IX, SnPP) on the epinephrine and phentolamine-induced electrocardiogram ST segment changes in vivo were investigated. The cardiac HO activity and the expression of HO-1 and HO-2 were significantly decreased in the aged rats and after ovariectomy. Estrogen depletion was accompanied by significant increases in the expression of IL-6 and TNF-α. The aged and ovariectomized animals exhibited a significantly elevated MPO activity and a significant ST segment depression. After pretreatment with SnPP augmented ST segment changes were determined. These findings demonstrate that the sensitivity to cardiac ischemia in estrogen depletion models is associated with suppression of the activity and expression of the HO system and increases in the secretion of proinflammatory cytokines and biomarkers.
Animal models have historically played a critical role in the exploration and characterization of disease pathophysiology and target identification and in the evaluation of novel therapeutic agents and treatments in vivo. Diabetes mellitus disease, commonly known as diabetes, is a group of metabolic disorders characterized by high blood glucose levels for a prolonged time. To avoid late complications of diabetes and related costs, primary prevention and early treatment are therefore necessary. Due to its chronic symptoms, new treatment strategies need to be developed, because of the limited effectiveness of the current therapies. We overviewed the pathophysiological features of diabetes in relation to its complications in type 1 and type 2 mice along with rat models, including Zucker Diabetic Fatty (ZDF) rats, BB rats, LEW 1AR1/-iddm rats, Goto-Kakizaki rats, chemically induced diabetic models, and Nonobese Diabetic mouse, and Akita mice model. The advantages and disadvantages that these models comprise were also addressed in this review. This paper briefly reviews the wide pathophysiological and molecular mechanisms associated with type 1 and type 2 diabetes, particularly focusing on the challenges associated with the evaluation and predictive validation of these models as ideal animal models for preclinical assessments and discovering new drugs and therapeutic agents for translational application in humans.
Many microbial and plant-derived metabolites contribute to the production of inflammatory mediators and the expression of pro-inflammatory molecules. Ophiobolin A (OPA) is a fungal secondary metabolite produced by Bipolaris species. The aim of our study was to examine the acute effects of this compound on inflammatory processes. Male Wistar rats were treated with 5% ethanol, 0.01 mg/kg OPA, 0.1 mg/kg OPA and 1.0 mg/kg OPA per os. After 24 h of the administrations, inflammatory mediators such as interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α) and myeloperoxidase (MPO) enzyme as well as heme oxygenase (HO) activity were measured in both plasma and cardiac tissue, along with serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). We found that OPA caused a significant elevation in the concentrations of IL-6 and TNF-α, increased MPO activity and decreased HO enzyme activity in the plasma. While OPA induces inflammation in the plasma, it did not change the level of inflammatory mediators in the cardiac tissue and the concentrations of serum ALT and AST. Our findings indicate that rapid release of inflammatory mediators by OPA promotes systemic inflammation. However, this acute OPA treatment does not show toxic effects on the cardiac tissue and the concentrations of liver enzymes.
Activated protein C (APC), an endogenous protein, inhibits inflammation and thrombosis and interrupts the coagulation cascade. Here, we investigated the effect of human recombinant APC on the development of neointimal hyperplasia in porcine coronary arteries. Yukon Choice bare metal stents were coated with 2.6 µg APC/mm2. Under general anesthesia, APC-coated and bare stents were implanted in the left anterior descending and circumflex coronary arteries of 10 domestic pigs. During the 4-week follow-up, animals were treated with dual antiplatelet therapy and neointimal hyperplasia was evaluated via histology. Scanning electron microscopy indicated successful but unequal coating of stents with APC; nearly complete drug release occurred within 4 h. Enzyme-linked immunosorbent assay revealed that intracoronary stent implantation rapidly increased the levels of monocyte chemoattractant protein-1, an effect that was inhibited by APC release from the coated stent. Fibrin deposition and adventitial inflammation were significantly decreased 1 month after implanting APC-coated stents versus bare stents, paralleled by significantly smaller neointimal area (0.98 ± 0.92 vs. 1.44 ± 0.91 mm2, P = 0.028), higher lumen area (3.47 ± 0.94 vs. 3.06 ± 0.91 mm2, P = 0.046), and lower stenosis area (22.2 ± 21.2 % vs. 32.1 ± 20.1 %, P = 0.034). Endothelialization was complete with APC-coated but not bare (90 %) stents. P-selectin immunostaining revealed significantly fewer activated endothelial cells in the neointima in the APC group (4.6 ± 1.9 vs. 11.6 ± 4.1 %, P < 0.001). Thus, short exposure of coronary arteries to APC reduced inflammatory responses, neointimal proliferation, and in-stent restenosis, offering a promising therapy to improve clinical outcomes of coronary stenting. However, coating stents with APC for prolonged, controlled drug release remains technically challenging.
