Phosphorylation of Akt <i>in vivo</i> (A) and <i>in vitro</i> (B) following different treatments.

<p>Values presented are mean±SEM. N = 6; G, ghrelin; GI, [D-Lys3]-GHRP-6, ghrelin inhibitor; W, wortmannin, a PI3K inhibitor. **<i>P<</i>0.01 vs. Sham, ^##<i>P<</i>0.01 vs. CPB or SCPB.</p

Myocardial apoptosis, MPO activity, reduced glutathione (GSH) and oxidized glutathione (GSSH) in rats subjected to cardiopulmonary bypass (CPB) with different treatments (n = 8/group).

<p>A, top: representative photomicrographs of in situ detection of apoptotic myocytes by terminal deoxynucleotidyl nick-end labeling (TUNEL) staining in ischemic heart tissue from rats subjected to 60 min CPB. Green fluorescence shows TUNEL-positive nuclei; blue fluorescence shows nuclei of total cardiomyocytes. Bottom: percentage of TUNEL-positive nuclei in heart tissue sections. (x20 objective) B: myocardial caspase-3 activity. C: MPO activity. D: reduced glutathione (GSH). E: oxidized glutathione (GSSH). Values presented are mean±SEM. G, ghrelin; GI, [D-Lys3]-GHRP-6, ghrelin inhibitor; W, wortmannin, a PI3K inhibitor. **<i>P</i><0.01 vs. Sham, ^##<i>P</i><0.01 vs. CPB, ^δ<i>P</i><0.05 vs. CPB+G.</p

Serum (A) and cardiac (B) tumor necrosis factor (TNF)-α and Serum (C) and cardiac (D) interleukin (IL)-6 production in rats subjected to CPB with different treatments (n = 8/group).

<p>Values presented are mean±SEM. G, ghrelin; GI, [D-Lys3]-GHRP-6, ghrelin inhibitor; W, wortmannin, a PI3K inhibitor. **<i>P<</i>0.01 vs. Sham, ^##<i>P<</i>0.01 vs. CPB, ^#<i>P<</i>0.05 vs. CPB, ^δ<i>P<</i>0.05 vs. CPB+G.</p

Effects of ghrelin on cardiac function in different groups after CPB (n = 8, mean±SEM).

<p>G, ghrelin; GI, [D-Lys3]-GHRP-6, ghrelin inhibitor; W, wortmannin, a PI3K inhibitor; HR, heart rate; MAP, mean arterial blood pressure; LVDP, left ventricular developed pressure; ±LVdP/dt_max, the instantaneous first derivation of left ventricle pressure.</p>*<p><i>P</i><0.05 vs. Sham,</p>#<p><i>P</i><0.05 vs. CPB,</p>δ<p><i>P</i><0.05 vs. CPB+G.</p

Myocardial injury in rats subjected to cardiopulmonary bypass (CPB) with different treatments (n = 8/group).

<p>Values presented are mean±SEM. A: serum cardiac troponin I (cTnI) level. B: serum lactate dehydrogenase (LDH) level. G, ghrelin; GI, [D-Lys3]-GHRP-6, ghrelin inhibitor; W, wortmannin, a PI3K inhibitor. **<i>P<</i>0.01 vs. Sham, ^##<i>P<</i>0.01 vs. CPB, ^δδ<i>P<</i>0.01 vs. CPB+G.</p

Cardiomyocyte contractile properties following CPB.

<p>(A) Resting cell length; (B) peak shortening (PS, normalized to cell length); (C) maximal velocity of shortening (+dL/dt); (D) maximal velocity of relaxtion (-dL/dt); (E) time-to-PS (TPS) and (F) time-to-90% relaxtion (TR90). Values presented are mean±SEM, n = 68–74 cells for each group from four rats per group. G, ghrelin; GI, [D-Lys3]-GHRP-6, ghrelin inhibitor; W, wortmannin, a PI3K inhibitor. *<i>P<</i>0.05 vs. Sham, ^#<i>P<</i>0.05 vs. CPB, ^δ<i>P<</i>0.05 vs. CPB+G.</p

α-Lipoic Acid Reduces Infarct Size and Preserves Cardiac Function in Rat Myocardial Ischemia/Reperfusion Injury through Activation of PI3K/Akt/Nrf2 Pathway

<div><p>Background</p><p>The present study investigates the effects and mechanisms of α-Lipoic acid (LA) on myocardial infarct size, cardiac function and cardiomyocyte apoptosis in rat hearts subjected to in vivo myocardial ischemia/reperfusion (MI/R) injury.</p> <p>Methodology/Principal Findings</p><p>Male adult rats underwent 30 minutes of ischemia followed by 3, 24, or 72 h of reperfusion. Animals were pretreated with LA or vehicle before coronary artery ligation. The level of MI/R- induced LDH and CK release, infarct size, cardiomyocyte apoptosis and cardiac functional impairment were examined and compared. Western blot analysis was performed to elucidate the mechanism of LA pretreatment. The level of inflammatory cytokine TNF-α released to serum and accumulated in injured myocardium as well as neutrophil accumulation in injured myocardium were also examined after MI/R injury. Our results reveal that LA administration significantly reduced LDH and CK release, attenuated myocardial infarct size, decreased cardiomyocytes apoptosis, and partially preserved heart function. Western blot analysis showed that LA pretreatment up-regulated Akt phosphorylation and Nrf2 nuclear translocation while producing no impact on p38MAPK activation or nitric oxide (NO) production. LA pretreatment also increased expression of HO-1, a major target of Nrf2. LA treatment inhibited neutrophil accumulation and release of TNF-α. Moreover, PI3K inhibition abolished the beneficial effects of LA.</p> <p>Conclusions/Significance</p><p>This study indicates that LA attenuates cardiac dysfunction by reducing cardiomyoctyes necrosis, apoptosis and inflammation after MI/R. LA exerts its action by activating the PI3K/Akt pathway as well as subsequent Nrf2 nuclear translocation and induction of cytoprotective genes such as HO-1.</p> </div

LA alleviates neutrophil infiltration and TNF-α levels elevation.

<p>LA reduced the MPO activity in I/R compared with vechicle and the wortmannin group (a). LA reduced serum levels of TNF-α compared with the I/R+V group and the wortmannin-pretreated group (b). LA reduced cardiac levels of TNF-α compared with the I/R+V group and the wortmannin-pretreated group (c). The columns and errors bars represent means and SEM. *<i>p</i><0.05 vs sham I/R, ^#<i>p</i><0.05 vs I/R+V, ^ψ<i>P</i><0.05 vs I/R+LA.</p

LA reduces LDH and CK release.

<p>LA reduced CK and LDH level after I/R injury in rat serum. PI3K inhibitor wortmannin cotreatment statistically increased the release of LDH and CK compared with LA treated alone. The columns and errors bars represent means and SEM. *<i>p</i><0.05 vs sham I/R, ^#<i>p</i><0.05 vs I/R+V, ^ψ<i>P</i><0.05 vs I/R+LA.</p

New Role of JAK2/STAT3 Signaling in Endothelial Cell Oxidative Stress Injury and Protective Effect of Melatonin

<div><p>Previous studies have shown that the JAK2/STAT3 signaling pathway plays a regulatory role in cellular oxidative stress injury (OSI). In this study, we explored the role of the JAK2/STAT3 signaling pathway in hydrogen peroxide (H₂O₂)-induced OSI and the protective effect of melatonin against (H₂O₂)-induced injury in human umbilical vein endothelial cells (HUVECs). AG490 (a specific inhibitor of the JAK2/STAT3 signaling pathway) and JAK2 siRNA were used to manipulate JAK2/STAT3 activity, and the results showed that AG490 and JAK2 siRNA inhibited OSI and the levels of p-JAK2 and p-STAT3. HUVECs were then subjected to H₂O₂ in the absence or presence of melatonin, the main secretory product of the pineal gland. Melatonin conferred a protective effect against H₂O₂, which was evidenced by improvements in cell viability, adhesive ability and migratory ability, decreases in the apoptotic index and reactive oxygen species (ROS) production and several biochemical parameters in HUVECs. Immunofluorescence and Western blotting showed that H₂O₂ treatment increased the levels of p-JAK2, p-STAT3, Cytochrome c, Bax and Caspase3 and decreased the levels of Bcl2, whereas melatonin treatment partially reversed these effects. We, for the first time, demonstrate that the inhibition of the JAK2/STAT3 signaling pathway results in a protective effect against endothelial OSI. The protective effects of melatonin against OSI, at least partially, depend upon JAK2/STAT3 inhibition.</p> </div