Cardioprotective effects of high-intensity interval training are mediated through microRNA regulation of mitochondrial and oxidative stress pathways

Haemodynamic, hormonal and renal actions of osteocrin in normal sheep

Osteocrin (OSTN) is an endogenous protein sharing structural similarities with the natriuretic peptides [NPs; atrial (ANP), B-type (BNP) and C-type (CNP) NP], which are hormones known for their crucial role in maintaining pressure/volume homeostasis. Osteocrin competes with the NPs for binding to the receptor involved in their clearance (NPR-C). In the present study, having identified, for the first time, the major circulating form of OSTN in human and ovine plasma, we examined the integrated haemodynamic, endocrine and renal effects of vehicle-controlled incremental infusions of ovine proOSTN (83-133) and its metabolism in eight conscious normal sheep. Incremental i.v. doses of OSTN produced stepwise increases in circulating concentrations of the peptide, and its metabolic clearance rate was inversely proportional to the dose. Osteocrin increased plasma levels of ANP, BNP and CNP in a dose-dependent manner, together with concentrations of their intracellular second messenger, cGMP. Increases in plasma cGMP were associated with progressive reductions in arterial pressure and central venous pressure. Plasma cAMP, renin and aldosterone were unchanged. Despite significant increases in urinary cGMP levels, OSTN administration was not associated with natriuresis or diuresis in normal sheep. These results support OSTN as an endogenous ligand for NPR-C in regulating plasma concentrations of NPs and associated cGMP-mediated bioactivity. Collectively, our findings support a role for OSTN in maintaining cardiovascular homeostasis.

Superior cardiometabolic and cellular adaptive responses to multiple versus single daily sessions of high-intensity interval training in Wistar rats

This study aimed to compare in rats the cardiometabolic and cellular adaptative responses to 8 weeks of high-intensity interval training (HIIT) performed in a single (1xHIIT) or three shorter daily sessions (3xHIIT). Male Wistar rats were assigned to untrained (n = 10), 1xHIIT (n = 10), and 3xHIIT (n = 10) groups. Both HIIT groups performed 15 min of a treadmill run five times per week for 8 weeks. The 1xHIIT performed single daily sessions of 15 min, and the 3xHIIT performed three daily sessions of 5 min with an interval of 4 h between sessions. Resting VO₂ and VO₂max were measured using a metabolic chamber; blood pressure and heart rate were measured by plethysmography; body composition was estimated by DEXA; Glucose and insulin tolerance tests were performed; after euthanasia, hearts, gastrocnemius, and visceral fat were harvested for analysis of cardiac function, histology, and morphology. Mitochondrial densities of the gastrocnemius and left ventricle muscles were determined by electron microscopy. 3xHIIT induced similar positive adaptative responses to 1xHIIT on resting VO₂ and VO₂max, cardiac function, and mitochondria density. 3xHIIT was superior to 1xHIIT in reducing visceral fat weight and adipocyte size and improving insulin tolerance. Multiple short daily bouts of HIIT may be superior to single HIIT daily sessions in improving cardiometabolic and cellular adaptations in rats.

Investigation of expression of myocardial miR-126, miR-29a and miR-222 as a potential marker in STZ- induced diabetic rats following interval and continuous exercise training

Purpose

Cardiac miRNAs are the recently discovered key modulators of gene expression in the heart which have been shown to contribute to both transcriptional and post-transcriptional regulation in diabetic cardiomyopathy. The aim of this study was to evaluate the protective effects of interval and continuous aerobic training on diabetic hearts by examining the expression of myocardial miR-126, miR-222 and miR-29a genes.

Methods

Thirty male wistar rats (200 ± 20 g) were randomly divided into six groups of healthy control (HC), diabetes control (DC), continuous training (CT), interval training (IT), continuous training with diabetes (CTD), and interval training with diabetes (ITD). Nicotinamide and Streptozotocin (STZ) were injected to induce type 2 diabetes. CT was performed with a speed of 10 to 22 m/min and 20 to 30 min and IT was performed with 10 to 39 m/min and total time of 15 min, five sessions per week for 6 weeks. Muscle expression of miR-126, miR-29a and miR-222 was determined by the RT-PCR method.

Results

The results show that gene expression of miR-126 was higher in IT (p < 0.01) compare to other groups. Also expression of miR-126 was higher in the CT compare to DC (p < 0.05) group. Gene expression of miR-222 was higher in aerobic groups than other groups (p < 0.01). Also expression of miR-222 was higher in ITD compare to the DC and CTD (p < 0.01) groups. Expression of miR-29a gene was higher in the aerobic groups compare to other groups. Also miR-29a was higher in the IT compare to CT (p < 0.01) group.

Conclusion

Diabetes decreased the expression of genes associated with the development of cardiac function. It seems that IT played a more effective role in cardiac protection than CT through higher miR-126, miR-222 and miR-29a gene expression.

Novel prevention insights into depletion of oxidative stress status through regular exercise and grape seed effective substance in heart ischemia rat model

Myocardial ischemia (MI) is recognized as the most frequent cardiovascular disease which is the dominant cause of global morbidity and mortality. Artificial intelligence tools and integrative data analysis revealed superoxide dismutase, catalase, glutathione peroxidase, gap junction protein α, myosin heavy chains, and zinc finger transcription factor GATA4 are engaged in oxidative stress and in cardiomyopathy. Network analysis indicated that MAPK3 might be the highest distribution property and cut point in this network, which could be a potential candidate for preventing and treating oxidative stress in heart tissue. Among antioxidant agents, grape seed extract (GSE) is an effective substance that altered antioxidant status in heart tissue. Considering drug discovery methods, we illustrated that GSE might target the MAPK3 protein with sufficient binding affinity. Moreover, we found that low- and moderate-intensity training might prevent the depletion of antioxidants after MI. GSE consumption altered the levels of superoxide dismutase, glutathione peroxidase, and catalase after 14 weeks. Therefore, the interaction of low- and moderate-intensity training and GSE had a synergistic effect on the antioxidant status and relative expression of the Mapk3. Moreover, the interaction of high-intensity training and GSE had a compensatory mechanism that could scavenge reactive oxygen species and improve endogenous antioxidants and modulate the Mapk3 level in MI rats. Consequently, we displayed positive influence and synergic effects of simultaneous GSE prescription and regular physical activity for 14 weeks to prevent acute and chronic heart ischemia cardioprotective phenomenon. Furthermore, the capacitation oxidative stress and relative expression of the Mapk3 was significantly increased by GSE and regular exercise.

Musclin Is Related to Insulin Resistance and Body Composition, but Not to Body Mass Index or Cardiorespiratory Capacity in Adults

BACKGROUND

We studied whether musclin function in humans is related to glycemic control, body composition, and cardiorespiratory capacity.

METHODS

A cross-sectional study was performed in sedentary adults with or without metabolic syndrome (MS). Serum musclin was measured by enzyme-linked immunosorbent assay. Insulin resistance (IR) was evaluated by the homeostatic model assessment (HOMA-IR). Body composition was determined by dual-energy X-ray absorptiometry and muscle composition by measuring carnosine in the thigh, a surrogate of fiber types, through proton magnetic resonance spectroscopy. Cardiorespiratory capacity was assessed through direct ergospirometry.

RESULTS

The control (n=29) and MS (n=61) groups were comparable in age (51.5±6.5 years old vs. 50.7±6.1 years old), sex (72.4% vs. 70.5% women), total lean mass (58.5%±7.4% vs. 57.3%±6.8%), and peak oxygen consumption (VO2peak) (31.0±5.8 mL O2./kg.min vs. 29.2±6.3 mL O2/kg.min). Individuals with MS had higher body mass index (BMI) (30.6±4.0 kg/m2 vs. 27.4± 3.6 kg/m2), HOMA-IR (3.5 [95% confidence interval, CI, 2.9 to 4.6] vs. 1.7 [95% CI, 1.1 to 2.0]), and musclin (206.7 pg/mL [95% CI, 122.7 to 387.8] vs. 111.1 pg/mL [95% CI, 63.2 to 218.5]) values than controls (P˂0.05). Musclin showed a significant relationship with HOMA-IR (β=0.23; 95% CI, 0.12 to 0.33; P˂0.01), but not with VO2peak, in multiple linear regression models adjusted for age, sex, fat mass, lean mass, and physical activity. Musclin was significantly associated with insulin, glycemia, visceral fat, and regional muscle mass, but not with BMI, VCO2peak, maximum heart rate, maximum time of work, or carnosine.

CONCLUSION

In humans, musclin positively correlates with insulinemia, IR, and a body composition profile with high visceral adiposity and lean mass, but low body fat percentage. Musclin is not related to BMI or cardiorespiratory capacity.

Circulating products of C-type natriuretic peptide and links with organ function in health and disease

Paracrine actions of CNP and rapid degradation at source severely limit study of CNP's many roles in vivo. However provided sensitive and validated assays are used, there is increasing evidence that low concentrations of bioactive CNP in plasma, and the readily detectable concentrations of the bio-inactive processed product of proCNP (aminoterminal proCNP), can be used to advance understanding of the hormone's role in pathophysiology. Provided renal function is normal, concordant changes in both CNP and NTproCNP reflect change in tissue production of proCNP whereas change in CNP alone results from altered rates of bioactive CNP degradation and are reflected in the ratio of NTproCNP to CNP. As already shown in juveniles, where plasma concentration of CNP products are higher and are associated with concurrent endochondral bone growth, measurements of plasma CNP products in mature adults have potential to clarify organ response to stress and injury. Excepting the role of CNP in fetal-maternal welfare, this review examines evidence linking plasma CNP products with function of a wide range of tissues in adults, including the impact of extraneous factors such as nutrients, hormone therapy and exercise.