Sex differences in weight gain, blood pressure control, and responses to melanocortin-4 receptor antagonism in offspring from lean and obese parents.

We examined potential sex differences in appetite and blood pressure (BP) responses to melanocortin-4 receptor (MC4R) blockade in offspring from lean and obese parents. Offspring from normal (N) diet-fed parents were fed N (NN) or high-fat (H) diets (NH) from weaning until adulthood. Offspring from obese H diet-fed parents were also fed N (HN) or H diets (HH). Adult male and female offspring were implanted with BP telemetry probes and intracerebroventricular cannulas to infuse MC4R antagonist or vehicle. Infusion of the MC4R antagonist SHU-9119 (1 nmol/h) for 7 days caused larger increases in calorie intake and body weight in obese compared with lean offspring. In male offspring, HH and HN groups exhibited higher baseline BP compared with NN and NH, and HH showed a greater reduction in BP during SHU-9119 infusion. In female offspring, HH also showed higher baseline BP and greater reduction in BP during MC4R blockade. SHU-9119 reduced heart rate in all groups, but reductions were more pronounced in offspring from lean parents. Combined α and ß-adrenergic blockade reduced BP more in male HH offspring compared with NN controls. Losartan reduced BP more in male NH, HN, and HH offspring compared with NN controls. Losartan and α- and ß-adrenergic blockade reduced BP similarly in all female groups. These results suggest that endogenous MC4R activity contributes to elevated BP in obese offspring from obese parents. Our findings also indicate important sex differences in the mechanisms of BP control in male and female offspring of obese parents.

Temporal changes in glucose metabolism reflect polarization in resident and monocyte-derived macrophages after myocardial infarction.

Introduction: Metabolic reprogramming from glycolysis to the mitochondrial tricarboxylic acid (TCA) cycle and oxidative phosphorylation may mediate macrophage polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. We hypothesized that changes in cardiac macrophage glucose metabolism would reflect polarization status after myocardial infarction (MI), ranging from the early inflammatory phase to the later wound healing phase. Methods: MI was induced by permanent ligation of the left coronary artery in adult male C57BL/6J mice for 1 (D1), 3 (D3), or 7 (D7) days. Infarct macrophages were subjected to metabolic flux analysis or gene expression analysis. Monocyte versus resident cardiac macrophage metabolism was assessed using mice lacking the Ccr2 gene (CCR2 KO). Results: By flow cytometry and RT-PCR, D1 macrophages exhibited an M1 phenotype while D7 macrophages exhibited an M2 phenotype. Macrophage glycolysis (extracellular acidification rate) was increased at D1 and D3, returning to basal levels at D7. Glucose oxidation (oxygen consumption rate) was decreased at D3, returning to basal levels at D7. At D1, glycolytic genes were elevated (Gapdh, Ldha, Pkm2), while TCA cycle genes were elevated at D3 (Idh1 and Idh2) and D7 (Pdha1, Idh1/2, Sdha/b). Surprisingly, Slc2a1 and Hk1/2 were increased at D7, as well as pentose phosphate pathway (PPP) genes (G6pdx, G6pd2, Pgd, Rpia, Taldo1), indicating increased PPP activity. Macrophages from CCR2 KO mice showed decreased glycolysis and increased glucose oxidation at D3, and decreases in Ldha and Pkm2 expression. Administration of dichloroacetate, a pyruvate dehydrogenase kinase inhibitor, robustly decreased pyruvate dehydrogenase phosphorylation in the non-infarcted remote zone, but did not affect macrophage phenotype or metabolism in the infarct zone. Discussion: Our results indicate that changes in glucose metabolism and the PPP underlie macrophage polarization following MI, and that metabolic reprogramming is a key feature of monocyte-derived but not resident macrophages.

Central Nervous System Actions of Leptin Improve Cardiac Function After Ischemia-Reperfusion: Roles of Sympathetic Innervation and Sex Differences.

Background Therapeutic strategies for preventing paradoxical reperfusion injury after myocardial ischemia are limited. We tested whether central nervous system actions of leptin induce important protective effects on cardiac function and metabolism after myocardial ischemia/reperfusion (I/R) injury, the role of cardiac sympathetic innervation in mediating these effects, and whether there are major sex differences in the cardioprotective effects of chronic central nervous system leptin infusion. Methods and Results Myocardial I/R was induced by temporary ligation of the left descending coronary artery in male and female Wistar rats instrumented with intracerebroventricular cannula in the lateral ventricle. Vehicle or leptin (0.62 µg/h) infusion was started immediately after reperfusion and continued for 28 days using osmotic minipumps connected to the intracerebroventricular cannula. Cardiac function was assessed by echocardiography, ventricular pressures, and exercise performance. Intracerebroventricular leptin treatment markedly attenuated cardiac dysfunction post-I/R as evidenced by improved ejection fraction (56.7±1.9 versus 22.6%±1.1%), maximal rate of left ventricle rise (11 680±2122 versus 5022±441 mm Hg) and exercise performance (-4.2±7.9 versus -68.2±3.8 Δ%) compared with vehicle-treated rats. Intracerebroventricular leptin infusion reduced infarct size in females, but not males, when compared with ad-lib fed or pair-fed saline-treated rats. Intracerebroventricular leptin treatment also increased cardiac NAD+/NADH content (≈10-fold) and improved mitochondrial function when compared with vehicle treatment. Cervical ganglia denervation did not attenuate the cardiac protective effects of leptin after I/R injury. Conclusions These data indicate that leptin, via its central nervous system actions, markedly improves overall heart function and mitochondrial metabolism after I/R injury regardless of sex, effects that are largely independent of cardiac sympathetic innervation.

Dimethyl fumarate preserves left ventricular infarct integrity following myocardial infarction via modulation of cardiac macrophage and fibroblast oxidative metabolism.

Myocardial infarction (MI) is one of the leading causes of mortality and cardiovascular disease worldwide. MI is characterized by a substantial inflammatory response in the infarcted left ventricle (LV), followed by transition of quiescent fibroblasts to active myofibroblasts, which deposit collagen to form the reparative scar. Metabolic shifting between glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) is an important mechanism by which these cell types transition towards reparative phenotypes. Thus, we hypothesized that dimethyl fumarate (DMF), a clinically approved anti-inflammatory agent with metabolic actions, would improve post-MI remodeling via modulation of macrophage and fibroblast metabolism. Adult male C57BL/6J mice were treated with DMF (10 mg/kg) for 3-7 days after MI. DMF attenuated LV infarct and non-infarct wall thinning at 3 and 7 days post-MI, and decreased LV dilation and pulmonary congestion at day 7. DMF improved LV infarct collagen deposition, myofibroblast activation, and angiogenesis at day 7. DMF also decreased pro-inflammatory cytokine expression (Tnf) 3 days after MI, and decreased inflammatory markers in macrophages isolated from the infarcted heart (Hif1a, Il1b). In fibroblasts extracted from the infarcted heart at day 3, RNA-Seq analysis demonstrated that DMF promoted an anti-inflammatory/pro-reparative phenotype. By Seahorse analysis, DMF did not affect glycolysis in either macrophages or fibroblasts at day 3, but enhanced macrophage OXPHOS while impairing fibroblast OXPHOS. Our results indicate that DMF differentially affects macrophage and fibroblast metabolism, and promotes anti-inflammatory/pro-reparative actions. In conclusion, targeting cellular metabolism in the infarcted heart may be a promising therapeutic strategy.