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The 17 beta-estradiol (E2) is a sex hormone that is most abundant and most active estrogen in premenopausal women. The importance of E2 in providing cardioprotection and reducing the occurrence of heart disease in women of reproductive age has been well recognized. There are three subtype of estrogen receptors (ERs), including ERα, ERβ and GPR30 have been identified and accumulating evidence reveal their roles on E2-mediated genomic and nongenomic pathway in cardiomyocytes against various cardiac insults. In this review, we focus on the estrogen and ERs mediated signaling pathways in cardiomyocytes that determines cardio-protection against various stresses and further discuss the clinical implication of ERs and phytoestrogens. Further we provide some insights on phytoeostrogens which may play as alternatives in estrogen replacement therapies.

Diabetes‐induced cardiovascular complications are mainly associated with high morbidity and mortality in patients with diabetes. Insulin‐like growth factor II receptor α (IGF‐IIRα) is a cardiac risk factor. In this study, we hypothesized IGF‐IIRα could also deteriorate diabetic heart injury. The results presented that both in vivo transgenic Sprague–Dawley rat model with specific IGF‐IIRα overexpression in the heart and in vitro myocardium H9c2 cells were used to investigate the negative function of IGF‐IIRα in diabetic hearts. The results showed that IGF‐IIRα overexpression aided hyperglycemia in creating more myocardial injury. Pro‐inflammatory factors, such as Tumor necrosis factor‐alpha, Interleukin‐6, Cyclooxygenase‐2, Inducible nitric oxide synthase, and Nuclear factor‐kappaB inflammatory cascade, are enhanced in the diabetic myocardium with cardiac‐specific IGF‐IIRα overexpression. Correspondingly, IGF‐IIRα overexpression in the diabetic myocardium also reduced the PI3K‐AKT survival axis and activated mitochondrial‐dependent apoptosis. Finally, both ejection fraction and fractional shortening were be significantly decrease in diabetic rats with cardiac‐specific IGF‐IIRα overexpression. Overall, all results provid clear evidence that IGF‐IIRα can enhance cardiac damage and is a harmful factor to the heart under high‐blood glucose conditions. However, the pathophysiology of IGF‐IIRα under different stresses and its downstream regulation in the heart still require further research. [ABSTRACT FROM AUTHOR]

Background: Skeletal muscle has extraordinary regenerative capabilities against challenge, mainly owing to its resident muscle stem cells, commonly identified by Pax7+, which expediently donate nuclei to the regenerating multinucleated myofibers. This local reserve of stem cells in damaged muscle tissues is replenished by undifferentiated bone marrow stem cells (CD34+) permeating into the surrounding vascular system. Objective: The purpose of the study was to provide a quantitative estimate for the changes in Pax7+ muscle stem cells (satellite cells) in humans following an acute bout of exercise until 96 h, in temporal relation to circulating CD34+ bone marrow stem cells. A subgroup analysis of age was also performed. Methods: Four databases (Web of Science, PubMed, Scopus, and BASE) were used for the literature search until February 2022. Pax7+ cells in human skeletal muscle were the primary outcome. Circulating CD34+ cells were the secondary outcome. The standardized mean difference (SMD) was calculated using a random-effects meta-analysis. Subgroup analyses were conducted to examine the influence of age, training status, type of exercise, and follow-up time after exercise. Results: The final search identified 20 studies for Pax7+ cells comprising a total of 370 participants between the average age of 21 and 74 years and 26 studies for circulating CD34+ bone marrow stem cells comprising 494 participants between the average age of 21 and 67 years. Only one study assessed Pax7+ cells immediately after aerobic exercise and showed a 32% reduction in exercising muscle followed by a fast repletion to pre-exercise level within 3 h. A large effect on increasing Pax7+ cell content in skeletal muscles was observed 24 h after resistance exercise (SMD = 0.89, p < 0.001). Pax7+ cells increased to ~ 50% above pre-exercise level 24–72 h after resistance exercise. For a subgroup analysis of age, a large effect (SMD = 0.81, p < 0.001) was observed on increasing Pax7+ cells in exercised muscle among adults aged > 50 years, whereas adults at younger age presented a medium effect (SMD = 0.64, p < 0.001). Both resistance exercise and aerobic exercise showed a medium overall effect in increasing circulating CD34+ cells (SMD = 0.53, p < 0.001), which declined quickly to the pre-exercise baseline level after exercise within 6 h. Conclusions: An immediate depletion of Pax7+ cells in exercising skeletal muscle concurrent with a transient release of CD34+ cells suggest a replenishment of the local stem cell reserve from bone marrow. A protracted Pax7+ cell expansion in the muscle can be observed during 24–72 h after resistance exercise. This result provides a scientific basis for exercise recommendations on weekly cycles allowing for adequate recovery time. Exercise-induced Pax7+ cell expansion in muscle remains significant at higher age, despite a lower stem cell reserve after age 50 years. More studies are required to confirm whether Pax7+ cell increment can occur after aerobic exercise. Clinical Trial Registration: Registered at the International Prospective Register of Systematic Reviews (PROSPERO) [identification code CRD42021265457]. [ABSTRACT FROM AUTHOR]

Glycogen content and contraction strongly regulate glycogen synthase (GS) activity, and the aim of the present study was to explore their effects and interaction on GS phosphorylation and kinetic properties. Glycogen content in rat epitrochlearis muscles was manipulated in vivo. After manipulation, incubated muscles with normal glycogen [NG, 210.9 [+ or -] 7.1 mmol/kg dry weight (dw)], low glycogen (LG; 108.1 [+ or -] 4.5 mmol/kg dw), and high glycogen (HG; 482.7 [+ or -] 42.1 mmol/kg dw) were contracted or rested before the studies of GS kinetic properties and GS phosphorylation (using phospho-specific antibodies). LG decreased and HG increased GS [K.sub.m] for UDP-glucose (LG: 0.27 [+ or -] 0.02 < NG: 0.71 [+ or -] 0.06 < HG: 1.11 [+ or -] 0.12 mM; P < 0.001). In addition, GS fractional activity inversely correlated with glycogen content (R = -0.70; P < 0.001; n = 44). Contraction decreased [K.sub.m] for UDP-glucose (LG: 0.14 [+ or -] 0.01 = NG: 0.16 [+ or -] 0.01 < HG: 0.33 [+ or -] 0.03 mM; P < 0.001) and increased GS fractional activity, and these effects were observed independently of glycogen content. In rested muscles, GS [Ser.sup.641] and [Ser.sup.7] phosphorylation was decreased in LG and increased in HG compared with NG. GSK-3[beta] [Ser.sup.9] and AMPK[alpha] [Thr.sup.172] phosphorylation was not modulated by glycogen content in rested muscles. Contraction decreased phosphorylation of GS [Ser.sup.641] at all glycogen contents. However, contraction increased GS [Ser.sup.7] phosphorylation even though GS was strongly activated. In conclusion, glycogen content regulates GS affinity for UDP-glucose and low affinity for UDP-glucose in muscles with high glycogen content may reduce glycogen accumulation. Contraction increases GS affinity for UDP-glucose independently of glycogen content and creates a unique phosphorylation pattern uridine diphosphate; adenosine monophosphate kinase; glycogen synthase kinase-3; acetyl-coenzyme A carboxylase; enzyme kinetic