Evidence of Altered Mitochondrial Protein Expression After Chronic Ethanol Consumption in the Aged Estrogen-Deficient Female Rat Heart

Loss of p27kip1 suppresses the myocardial senescence caused by estrogen deficiency

Estrogen deficiency accelerates the aging process and increases the risk of developing cardiovascular disease (CVD). Apoptosis is one of the important mechanisms of aging. p27^kip1 is a cyclin-dependent kinase inhibitor that can regulate cell cycle, apoptosis, and cell motility. p27^kip1 overexpression can inhibit cell cycle and increase apoptosis so it has been considered as a marker of aging. In the present study, bilateral ovariectomy (OVX) was performed as a model for menopause in wild-type (WT) and p27^kip1 knockout (KO) mice to assess the effects of p27^kip1 loss in myocardial aging caused by estrogen deficiency. We found that myocardial fibrosis and heart weight/body weight ratio of mice in the OVX group and p27^kip1 KO group were significantly increased. Echocardiography showed that the left ventricular diameter and volume of the WT OVX group increased significantly and the cardiac function decreased. However, there was no significant difference in the results of echocardiography between the two p27^kip1 KO groups. The aging and apoptosis indexes in OVX group were increased significantly, However, the indexes in p27^kip1 KO mice were decreased. The expression of antioxidant indexes in OVX group was decreased significantly and p27^kip1 KO can improve the antioxidant ability. These results provided that estrogen deficiency increased oxidative stress and apoptosis, accelerated aging of heart. p27^kip1 KO can partly delay the aging and apoptosis of heart through upregulated antioxidant enzymes.

Inhibition of programmed necrosis limits infarct size through altered mitochondrial and immune responses in the aged female rat heart

Both advancing age and estrogen loss exacerbate acute myocardial infarction in the female heart. However, the mechanistic underpinnings of age-related differences in cell death after ischemia-reperfusion (I/R) injury in female subjects and reductions in cardioprotective reserve capacity remain largely unexplored. The aim of the present study was to determine the efficacy of programmed necrosis inhibition on infarct size reduction and preservation of left ventricular (LV) function after I/R injury with female aging. Fischer 344 rats were ovariectomized (OVX) at 15 mo and studied at 24 mo (MO OVX) versus adult rats with intact ovaries (6 mo). After in vivo coronary artery ligation (55-min ischemia and 2- or 6-h reperfusion), necrostatin-1 (Nec-1; 3.5 or 5.7 mg/kg) delivered upon reperfusion significantly reduced infarct size by 37% and improved LV function in the MO OVX group ( P < 0.01). Although age-associated elevations in cyclophilin D and mitochondrial acetylation ( P < 0.001) were unaffected by Nec-1, profound reductions in IL-1, IL-6, and TNF-α ( P < 0.05) as well as cardiac immune cell infiltration were observed in MO OVX but not adult rats. We conclude that chronic inflammation and postmenopausal estrogen deficiency conspire to exacerbate acute infarction through a mechanism involving exaggerated mitochondria-mediated programmed necrosis through receptor-interacting protein 1 signaling. Modulatory effects of programmed necrosis inhibition on proinflammatory cytokine production after I/R reveal a potentially important mechanistic target to restore and preserve cardiac function in the OVX aged female heart. NEW & NOTEWORTHY Myocardial infarct size reduction by inhibition of programmed necrosis in aged female subjects suggests a dominant cell death pathway. Alterations in mitochondrial protein levels and acetylation underscore a mitochondria-dependent mechanism, whereas the profound cytokine reduction in aged subjects alone points to a divergent role for immune modulation of programmed necrosis and viable therapeutic target.

Role of autophagy and regulatory mechanisms in alcoholic cardiomyopathy

Alcoholism is accompanied with a high incidence of cardiac morbidity and mortality due to the development of alcoholic cardiomyopathy, manifested as dilation of one or both ventricles, reduced ventricular wall thickness, myofibrillary disarray, interstitial fibrosis, hypertrophy and contractile dysfunction. Several theories have been postulated for the etiology of alcoholic cardiomyopathy including ethanol/acetaldehyde toxicity, mitochondrial production of reactive oxygen species, oxidative injury, apoptosis, impaired myofilament Ca²⁺ sensitivity and protein synthesis, altered fatty acid extraction and deposition, as well as accelerated protein catabolism. In particular, buildup of long-lived or dysfunctional organelles has been reported to contribute to cardiac structural and functional damage following alcoholism. Removal of cell debris and defective organelles by autophagy is essential to the maintenance of cardiac homeostasis in physiological and pathological conditions. However, insufficient understanding is currently available with regards to the involvement of autophagy in the pathogenesis of alcoholic cardiomyopathy. This review summarizes the recent findings on the pathophysiological role of dysregulated autophagy in one set and development of alcoholic cardiomyopathy. A thorough understanding of how autophagy is affected in alcoholism, and subsequently, contributes to the pathogenesis of alcoholic heart injury, will offer therapeutic guidance towards the management of alcoholic cardiomyopathy.