Resveratrol regulates autophagy signaling in chronically ischemic myocardium

ObjectiveAutophagy is a cellular process by which damaged components are removed. Although autophagy can result in cell death, when optimally regulated, it might be cardioprotective. Resveratrol is a naturally occurring polyphenol also believed to be cardioprotective. Using a clinically relevant swine model of metabolic syndrome, we investigated the effects of resveratrol on autophagy in the chronically ischemic myocardium.MethodsYorkshire swine were fed a regular diet (n = 7), a high cholesterol diet (n = 7), or a high cholesterol diet with supplemental resveratrol (n = 6). After 4 weeks, an ameroid constrictor was surgically placed on the left circumflex artery to induce chronic myocardial ischemia. The diets were continued another 7 weeks, and then the ischemic and nonischemic myocardium were harvested for protein analysis.ResultsIn the ischemic myocardium, a high cholesterol diet partly attenuated the autophagy, as determined by an increase in phosphorylated mammalian target of rapamycin (p-mTOR) and a decrease in p70 S6 kinase (P70S6K), lysosome-associated membrane protein (LAMP)-2, and autophagy-related gene 12-5 conjugate (ATG 12-5; P < .05). The addition of resveratrol blunted many of these changes, because the p-mTOR, P70S6K, and LAMP-2 levels were not significantly altered from those of the pigs fed a regular diet. Other autophagy markers were increased with a high cholesterol diet, including light chain 3A-II and beclin 1 (P < .05). In the nonischemic myocardium, beclin 1 was decreased in the high cholesterol-fed pigs (P < .05); otherwise no significant changes in protein expression were noted among the 3 groups.ConclusionsIn the chronically ischemic myocardium, resveratrol partly reversed the effects of a high cholesterol diet on autophagy. This might be a mechanism by which resveratrol exerts its cardioprotective effects

Metabolic Syndrome Impairs Notch Signaling and Promotes Apoptosis in Chronically Ischemic Myocardium

Objective Impaired angiogenesis is a known consequence of metabolic syndrome (MetS), however, the mechanism is not fully understood. Recent studies have shown that the Notch signaling pathway is an integral component of cardiac angiogenesis. We tested in a clinically relevant swine model the effects of MetS on Notch and apoptosis signaling in chronically ischemic myocardium. Methods Ossabaw swine were fed either a regular diet (CTL, n=8) or a high-cholesterol diet (MetS, n=8) to induce MetS. An ameroid constrictor was placed to induce chronic myocardial ischemia. Eleven weeks later, animals underwent cardiac harvest of the ischemic myocardium. Results There was down-regulation of pro-angiogenesis proteins Notch2, Notch4, Jagged2, Ang1 and ENOS in the MetS group compared to CTL. There was also up-regulation of pro-apoptosis protein Caspase8, and down-regulation of anti-angiogenesis protein pFOX03, and pro-survival proteins pP38 and HSP90 in the MetS group. Cell death was increased in the MetS group compared to CTL. Both CTL and MetS groups had similar arteriolar count and capillary density, and Notch3 and Jagged1 were both similarly concentrated in the smooth muscle wall in both groups. Conclusions MetS in chronic myocardial ischemia significantly impairs Notch signaling by down regulating Notch receptors, ligands and pro-angiogenesis proteins. MetS also increases apoptosis signaling, decreases survival signaling and increases cell death in chronically ischemic myocardium. Although short-term angiogenesis appears unaffected in this model of early MetS, the molecular signals for angiogenesis are impaired, thus suggesting that inhibition of Notch signaling may underlie decreased angiogenesis in later stages of MetS

The Behavioral and Physiological Effects of High-fat Diet and Alcohol Consumption: Sex Differences in C57BL6/J Mice

Background and Objective: Animal studies can be a great tool to investigate sex differences in a variety of different ways, including behavioral and physiological responses to drug treatments and different “lifestyle variables” such as diets. Consumption of both high-fat diets and alcohol is known to affect anxiety behaviors and overall health. This project investigated how high-fat diet and alcohol access and its combination affected the behavior and physiology of male and female C57BL/6J mice. Method: Mice were separated into three food groups: high-fat diet, 10% fat diet, and regular chow, and each group was paired with either water or 10% alcohol. Behavioral assays included diet and alcohol preference, light-dark box, open field, and feeding and drinking measurements. Physiological measures included glucose tolerance tests and measurement of brain-derived neurotrophic factor, insulin, and leptin levels. Results: Females and males differed in the open field, as male mice decreased activity, while females increased activity when consuming high-fat diet. While females consumed more ethanol than males, alcohol consumption was able to improve glucose tolerance and increase anxiety in both sexes. Lastly, females were more resistant to the physiological changes caused by high-fat diet than males, as females consuming high-fat diet exhibited decreased insulin secretion, less change to brain-derived neurotrophic factor levels, and better glucose tolerance than males consuming high-fat diet. Conclusion: These results suggest that the response to high-fat diet and alcohol consumption is sex dependent and that males are more affected both behaviorally and physiologically by high-fat diet compared to females

Metformin alters the insulin signaling pathway in ischemic cardiac tissue in a swine model of metabolic syndrome

ObjectiveThe purpose of this study is to evaluate the effect of metformin on insulin signaling in ischemic cardiac tissue in a swine model of metabolic syndrome.MethodsOssabaw miniswine were fed either a regular diet (Ossabaw control [OC]) or a hypercaloric diet (Ossabaw high cholesterol [OHC], Ossabaw high cholesterol with metformin [OHCM]). After 9 weeks, all animals underwent placement of an ameroid constrictor to the left circumflex artery to induce chronic ischemia. OHC animals were continued on a hypercaloric diet alone; the OHCM group was supplemented with metformin in addition to the hypercaloric diet. Seven weeks after ameroid placement, myocardial perfusion was measured and ischemic cardiac tissue was harvested for protein expression and histologic analysis.ResultsThe OHC and OHCM groups had significantly higher body mass indices and serum insulin levels compared with the OC group. There were no differences in myocardial perfusion in the chronically ischemic territories. In the OHC group, there was upregulation of both an activator of insulin signaling insulin receptor substrate 1, and an inhibitor of insulin signaling phosphorylated insulin receptor substrate 2. In the OHCM group, there was upregulation of activators of insulin signaling including phosphorylated adenosine monophosphate-activated protein kinase α, protein kinase B, phosphorylated protein kinase B, mammalian target of rapamycin, phosphorylated mammalian target of rapamycin, and phosphoinostitide 3-kinase, and upregulation of inhibitors including phosphorylated insulin receptor substrate 1, phosphorylated insulin receptor substrate 2, and retinol binding protein 4. Histologic analysis demonstrated increased expression of glucose transporter 1 at the plasma membrane in the OHCM group, but there was no difference in cardiomyocyte glycogen stores among groups.ConclusionsMetformin treatment in the context of metabolic syndrome and myocardial ischemia dramatically upregulates the insulin signaling pathway in chronically ischemic myocardium, which is at the crossroads of known metabolic and survival benefits of metformin

Atrial Fibrillation, Neurocognitive Decline and Gene Expression After Cardiopulmonary Bypass

ABSTRACT OBJECTIVE: Atrial fibrillation and neurocognitive decline are common complications after cardiopulmonary bypass. By utilizing genomic microarrays we investigate whether gene expression is associated with postoperative atrial fibrillation and neurocognitive decline. METHODS: Twenty one cardiac surgery patients were prospectively matched and underwent neurocognitive assessments pre-operatively and four days postoperatively. The whole blood collected in the pre-cardiopulmonary bypass, 6 hours after-cardiopulmonary bypass, and on the 4th postoperative day was hybridized to Affymetrix Gene Chip U133 Plus 2.0 Microarrays. Gene expression in patients who developed postoperative atrial fibrillation and neurocognitive decline (n=6; POAF+NCD) was compared with gene expression in patients with postoperative atrial fibrillation and normal cognitive function (n=5; POAF+NORM) and patients with sinus rhythm and normal cognitive function (n=10; SR+NORM). Regulated genes were identified using JMP Genomics 4.0 with a false discovery rate of 0.05 and fold change of >1.5 or <-1.5. RESULTS: Eleven patients developed postoperative atrial fibrillation. Six of these also developed neurocognitive decline. Of the 12 patients with sinus rhythm, only 2 developed neurocognitive decline. POAF+NCD patients had unique regulation of 17 named genes preoperatively, 60 named genes six hours after cardiopulmonary bypass, and 34 named genes four days postoperatively (P<0.05) compared with normal patients. Pathway analysis demonstrated that these genes are involved in cell death, inflammation, cardiac remodeling and nervous system function. CONCLUSION: Patients who developed postoperative atrial fibrillation and neurocognitive decline after cardiopulmonary bypass may have differential genomic responses compared to normal patients and patients with only postoperative atrial fibrillation, suggesting common pathophysiology for these conditions. Further exploration of these genes may provide insight into the etiology and improvements of these morbid outcomes