Physiological research最新文献

Muscarinic acetylcholine receptors are metabotropic G-protein coupled receptors. Muscarinic receptors in the cardiovascular system play a central role in its regulation. Particularly M2 receptors slow down the heart rate by reducing the impulse conductivity through the atrioventricular node. In general, activation of muscarinic receptors has sedative effects on the cardiovascular system, including vasodilation, negative chronotropic and inotropic effects on the heart, and cardioprotective effects, including antifibrillatory effects. First, we review the signaling of individual subtypes of muscarinic receptors and their involvement in the physiology and pathology of the cardiovascular system. Then we review age and disease-related changes in signaling via muscarinic receptors in the cardiovascular system. Finally, we review molecular mechanisms involved in cardioprotection mediated by muscarinic receptors leading to negative chronotropic and inotropic and antifibrillatory effects on heart and vasodilation, like activation of acetylcholine-gated inward-rectifier K+-currents and endothelium-dependent and -independent vasodilation. We relate this knowledge with well-established cardioprotective treatments by vagal stimulation and muscarinic agonists. It is well known that estrogen exerts cardioprotective effects against atherosclerosis and ischemia-reperfusion injury. Recently, some sex hormones and neurosteroids have been shown to allosterically modulate muscarinic receptors. Thus, we outline possible treatment by steroid-based positive allosteric modulators of acetylcholine as a novel pharmacotherapeutic tactic. Keywords: Muscarinic receptors, Muscarinic agonists, Allosteric modulation, Cardiovascular system, Cardioprotection, Steroids.

The lifestyle of human society is drifting apart from the natural environmental cycles that have influenced it since its inception. These cycles were fundamental in structuring the daily lives of people in the pre-industrial era, whether they were seasonal or daily. Factors that disrupt the regularity of human behaviour and its alignment with solar cycles, such as late night activities accompanied with food intake, greatly disturb the internal temporal organization in the body. This is believed to contribute to the rise of the so-called diseases of civilization. In this review, we discuss the connection between misalignment in daily (circadian) regulation and its impact on health, with a focus on cardiovascular and metabolic disorders. Our aim is to review selected relevant research findings from laboratory and human studies to assess the extent of evidence for causality between circadian clock disruption and pathology. Keywords: Circadian clock, Chronodisruption, Metabolism, Cardiovascular disorders, Spontaneously hypertensive rat, Human, Social jetlag, Chronotype.

In 2023, six decades have elapsed since the first experimental work on the heart muscle was published, in which a member of the Institute of Physiology of the Czech Academy of Sciences participated as an author; Professor Otakar Poupa was the founder and protagonist of this research domain. Sixty years - more than half of the century - is certainly significant enough anniversary that is worth looking back and reflecting on what was achieved during sometimes very complicated periods of life. It represents the history of an entire generation of experimental cardiologists; it is possible to learn from its successes and mistakes. The objective of this review is to succinctly illuminate the scientific trajectory of an experimental cardiological department over a 60-year span, from its inaugural publication to the present. The old truth - historia magistra vitae - is still valid. Keywords: Heart, Adaptation, Development, Hypoxia, Protection.

A new class of antidiabetic drugs - gliflozins (inhibitors of sodium glucose cotransporter-2; SGLT-2i) stimulate glucose and sodium excretion, thereby contributing to improved glycemic control, weight loss and blood pressure reduction in diabetic patients. Large clinical trials in patients with type 2 diabetes treated with empagliflozin, canagliflozin or dapagliflozin have demonstrated their excellent efficacy in improving many cardiovascular outcomes, including the reduction of death from cardiovascular diseases, non-fatal myocardial infarction or stroke, and hospitalization for heart failure. Moreover, the beneficial effects of SGLT-2i were also demonstrated in the decrease in proteinuria, which leads to a lower risk of progression to end-stage renal disease and thus a delay in initiation of the renal replacement therapy. Unexpectedly, their cardioprotective and renoprotective effects have been demonstrated not only in patients with diabetes but also in those without diabetes. Recently, much effort has been focused on patients with heart failure (either with reduced or preserved ejection fraction) or liver disease. Experimental studies have highlighted pleiotropic effects of SGLT-2 inhibitors beyond their natriuretic and glycosuric effects, including reduction of fibrosis, inflammation, reactive oxygen species, and others. Our results in experimental non-diabetic models of hypertension, chronic kidney disease and heart failure are partially consistent with these findings. This raises the question of whether the same mechanisms are at work in diabetic and non-diabetic conditions, and which mechanisms are responsible for the beneficial effects of gliflozins under non-diabetic conditions. Are these effects cardio-renal, metabolic, or others? This review will focus on the effects of gliflozins under different pathophysiological conditions, namely in hypertension, chronic kidney disease, and heart failure, which have been evaluated in non-diabetic rat models of these diseases. Key words: SGLT-2 inhibitor, hypertension, chronic kidney disease, heart failure, liver disease, rat.

RNA modifications affect key stages of the RNA life cycle, including splicing, export, decay, and translation. Epitranscriptomic regulations therefore significantly influence cellular physiology and pathophysiology. Here, we selected some of the most abundant modifications and reviewed their roles in the heart and in cardiovascular diseases: N6-methyladenosine (m6A), N6,2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), pseudouridine (?), 5 methylcytidine (m5C), and inosine (I). Dysregulation of epitranscriptomic machinery affecting these modifications vastly changes the cardiac phenotype and is linked with many cardiovascular diseases such as myocardial infarction, cardiomyopathies, or heart failure. Thus, a deeper understanding of these epitranscriptomic changes and their regulatory mechanisms can enhance our knowledge of the molecular underpinnings of prevalent cardiac diseases, potentially paving the way for novel therapeutic strategies. Keywords: Epitranscriptomics, RNA modifications, Epigenetics, m6A, RNA, Heart.

This study investigated the effect of eicosapentaenoic acid (EPA) on insulin resistance in pregnant mice with gestational diabetes mellitus (GDM) and underlying mechanism. C57BL/6 mice fed with a high-fat diet for 4 weeks and the newly gestated were selected and injected with streptozotocin for GDM modeling. We demonstrated that the fasting insulin levels (FINS) and insulin sensitivity index (ISI) in serum and blood glucose level were significantly higher in GDM group than in normal control (NC) group. The low or high dose of EPA intervention reduced these levels, and the effect of high dose intervention was more significant. The area under the curve in GDM group was higher than that of NC group, and then gradually decreased after low or high dose of EPA treatment. The serum levels of TC, TG and LDL were increased in GDM group, while decreased in EPA group. GDM induced down-regulation of HDL level, and the low or high dose of EPA gradually increased this level. The levels of p-AKT2Ser, p-IRS-1Tyr, GLUT4, and ratios of pIRS-1Tyr/IRS-1 and pAKT2Ser/AKT2 in gastrocnemius muscle were reduced in GDM group, while low or high dose of EPA progressively increased these alterations. GDM enhanced TLR4, NF-kappaB p65, IL-1beta, IL-6 and TNF-alpha levels in placental tissues, and these expressions were declined at different dose of EPA, and the decrease was greater at high dose. We concluded that EPA receded the release of inflammatory factors in the placental tissues by inhibiting the activation of TLR4 signaling, thereby alleviating the IR.

Nonsteroidal anti-inflammatory drugs are the most widely used drugs for Parkinson's disease (PD), of which ibuprofen shows positive effects in suppressing symptoms; however, the associated risk needs to be addressed in different pathological stages. Initially, we developed an initial and advanced stage of the Parkinson disease mouse model by intraperitoneal injection of MPTP (20 mg/kg; 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine) for 10 and 20 days, respectively. Subsequently, ibuprofen treatment was administered for 2 months, and a pole test, rotarod test, histology, immunohistochemistry, and western blotting were performed to determine neuronal motor function. Histological analysis for 10 days after mice were injected with MPTP showed the onset of neurodegeneration and cell aggregation, indicating the initial stages of Parkinson's disease. Advanced Parkinson's disease was marked by Lewy body formation after another 10 days of MPTP injection. Neurodegeneration reverted after ibuprofen therapy in initial Parkinson's disease but not in advanced Parkinson's disease. The pole and rotarod tests confirmed that motor activity in the initial Parkinson disease with ibuprofen treatment recovered (p<0.01). However, no improvement was observed in the ibuprofen-treated mice with advanced disease mice. Interestingly, ibuprofen treatment resulted in a significant improvement (p<0.01) in NURR1 (Nuclear receptor-related 1) expression in mice with early PD, but no substantial improvement was observed in its expression in mice with advanced PD. Our findings indicate that NURR1 exerts anti-inflammatory and neuroprotective effects. Overall, NURR1 contributed to the effects of ibuprofen on PD at different pathological stages.

beta3-adrenergic activation causes Ca2+ release from the mitochondria and subsequent Ca2+ release from the endoplasmic reticulum (ER), evoking store-operated Ca2+ entry (SOCE) due to Ca2+ depletion from the ER in mouse brown adipocytes. In this study, we investigated how Ca2+ depletion from the ER elicits SOCE in mouse brown adipocytes using fluorometry of intracellular Ca2+ concentration ([Ca2+]i). The administration of cyclopiazonic acid (CPA), a reversible sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) pump blocker in the ER, caused an increase in [Ca2+]i. Moreover, CPA induced SOCE was suppressed by the administration of a Ca2+ free Krebs solution and the transient receptor potential canonical 6 (TRPC6) selective blockers 2-APB, ML-9 and GsMTx-4 but not Pico145, which blocks TRPC1/4/5. Administration of TRPC6 channel agonist 1-oleoyl-2-acetyl-sn-glycerol (OAG) and flufenamic acid elicited Ca2+ entry. Moreover, our RT-PCR analyses detected mRNAs for TRPC6 in brown adipose tissues. In addition, western blot analyses showed the expression of the TRPC6 protein. Thus, TRPC6 is one of the Ca2+ pathways involved in SOCE. These modes of Ca2+ entry provide the basis for heat production via activation of Ca2+-dependent dehydrogenase and the expression of uncoupling protein 1 (UCP1). Enhancing thermogenic metabolism in brown adipocytes may serve as broad therapeutic utility to reduce obesity and metabolic syndrome.

No information is available about sex-related differences in unloading-induced cardiac atrophy. We aimed to compare the course of unloading-induced cardiac atrophy in intact (without gonadectomy) male and female rats, and in animals after gonadectomy, to obtain insight into the influence of sex hormones on this process. Heterotopic heart transplantation (HT((x)) was used as a model for heart unloading. Cardiac atrophy was assessed as the weight ratio of heterotopically transplanted heart weight (HW) to the native HW on days 7 and 14 after HTx in intact male and female rats. In separate experimental groups, gonadectomy was performed in male and female recipient animals 28 days before HT(x) and the course of cardiac atrophy was again evaluated on days 7 and 14 after HT(x). In intact male rats, HT(x) resulted in significantly greater decreases in whole HW when compared to intact female rats. The dynamics of the left ventricle (LV) and right ventricle (RV) atrophy after HT(x) was quite similar to that of whole hearts. Gonadectomy did not have any significant effect on the decreases in whole HW, LV, and RV weights, with similar results in male and female rats. Our results show that the development of unloading-induced cardiac atrophy is substantially reduced in female rats when compared to male rats. Since gonadectomy did not alter the course of cardiac atrophy after HTx, similarly in both male and female rats, we conclude that sex-linked differences in the development of unloading-induced cardiac atrophy are not caused by the activity of sex hormones.

MicroRNAs have been shown to potentially function in cerebral ischemia/reperfusion (IR) injury. This study aimed to examine the expression of microRNA-320 (miR-320) in cerebral IR injury and its involvement in cerebral mitochondrial function, oxidative stress, and inflammatory responses by targeting the HMGB1/NF-kappaB axis. Sprague-Dawley rats were subjected to middle cerebral artery occlusion to simulate cerebral IR injury. The cerebral expression of miR-320 was assessed using qRT-PCR. Neurological function, cerebral infarct volume, mitochondrial function, oxidative stress, and inflammatory cytokines were evaluated using relevant methods, including staining, fluorometry, and ELISA. HMGB1 expression was analyzed through Western blotting. The levels of miR-320, HMGB1, neurological deficits, and cerebral infarction were significantly higher after IR induction. Intracerebral overexpression of miR-320 resulted in substantial neurological deficits, increased infarct volume, elevated levels of 8-isoprostane, NF-kappaBp65, TNF-alpha, IL-1beta, ICAM-1, VCAM-1, and HMGB1 expression. It also promoted the loss of mitochondrial membrane potential and ROS levels while reducing MnSOD and GSH levels. Downregulation of miR-320 and inhibition of HMGB1 activity significantly reversed the outcomes of cerebral IR injury. MiR-320 plays a negative role in regulating cerebral inflammatory/oxidative reactions induced by IR injury by enhancing HMGB1 activity and modulating mitochondrial function.