Twelve weeks of treadmill exercise training with green tea extract reduces myocardial oxidative stress and alleviates cardiomyocyte apoptosis in aging rat: The emerging role of BNIP3 and HIF-1α/IGFBP3 pathway

In this study, we consider the effect of treadmill exercise training, green tea extract, and combination of exercise training with green tea extract, in aging rat cardiac myocytes apoptosis markers (i.e., HIF-1α, BNIP3, Bax, IGFBP3, Bcl-2, caspase-3, MDA, GPx, Bax/Bcl-2 ratio, and hematoxylin and eosin). Twenty-four rats (male, Wistar) were divided into four groups: (I) control (n = 6), (II) green tea extract (n = 6), (III) exercise (n = 6), and (IV) exercise + green tea extract (n = 6). Exercise groups performed 12 weeks of running on a rodent treadmill at 17-27 m.min^-1 (60-75% vo2peak) for 5 days per week. Green tea extract involved 300 mg.kg^-1 , 5 days per week for 12 weeks. After being euthanized, the blood and heart were collected for glutathione peroxidase (GPx) activity, malondialdehyde (MDA), HIF-1α, BNIP3, insulin-like growth factor-binding protein-3 (IGFBP3), Bax, Bcl-2, caspase-3, Bax/Bcl-2 ratio, and hematoxylin and eosin level measurements. Compared to control, the ANOVA demonstrated significant effects of green tea extract (F = 14.646 to 32.453, p = .009 to .001, η = 0.295 to 0.715) and exercise training (F = 9.213 to 133.828, p = .007 to .001, η = 0.315 to η = 0.870) on HIF-1a, BNIP3, Bax, IGFBP3, Bcl-2, caspase-3, MDA, GPx, and Bax/Bcl-2 ratio. However, the combination of green tea extract and exercise had no effect on the aforementioned apoptosis markers when compared to isolated green tea extract or isolated exercise (F = 0.002 to 4.068, p = .057 to .968, and η = 0.001 to 0.169). PRACTICAL APPLICATIONS: Isolated exercise training and green tea extract may provide a cardioprotective effect on aging-induced apoptosis through the downregulation of HIF-1α, BNIP3, and IGFBP3 in the heart muscle. However, further research is needed to clarify the effects of combining exercise and green tea.

The Hypothermic Influence on CHOP and Ero1-α in an Endoplasmic Reticulum Stress Model of Cerebral Ischemia

Hypoxia induced endoplasmic reticulum stress causes accumulation of unfolded proteins in the endoplasmic reticulum and activates the unfolded protein response, resulting in apoptosis through CCAAT-enhancer-binding protein homologous protein (CHOP) activation. In an in vitro and in vivo model of ischemic stroke, we investigated whether hypothermia regulates the unfolded protein response of CHOP and Endoplasmic reticulum oxidoreductin-α (Ero1-α), because Ero1-α is suggested to be a downstream CHOP target. The gene expression of CHOP and Ero1-α was measured using Quantitative-PCR (Q-PCR) in rat hippocampi following global cerebral ischemia, and in hypoxic pheochromocytoma cells during normothermic (37 °C) and hypothermic (31 °C) conditions. As a result of ischemia, a significant increase in expression of CHOP and Ero1-α was observed after three, six and twelve hours of reperfusion following global ischemia. A stable increase in CHOP expression was observed throughout the time course (p < 0.01, p < 0.0001), whereas Ero1-α expression peaked at three to six hours (p < 0.0001). Induced hypothermia in hypoxia stressed PC12 cells resulted in a decreased expression of CHOP after three, six and twelve hours (p < 0.0001). On the contrary, the gene expression of Ero1-α increased as a result of hypothermia and peaked at twelve hours (p < 0.0001). Hypothermia attenuated the expression of CHOP, supporting that hypothermia suppress endoplasmic reticulum stress induced apoptosis in stroke. As hypothermia further induced up-regulation of Ero1-α, and since CHOP and Ero1-α showed differential regulation as a consequence of both disease (hypoxia) and treatment (hypothermia), we conclude that they are regulated independently.