Alcohol and Apoptosis: Friends or Foes?

Alcohol abuse causes 79,000 deaths stemming from severe organ damage in the United States every year. Clinical manifestations of long-term alcohol abuse on the cardiac muscle include defective contractility with the development of dilated cardiomyopathy and low-output heart failure; which has poor prognosis with less than 25% survival for more than three years. In contrast, low alcohol consumption has been associated with reduced risk of cardiovascular disease, however the mechanism of this phenomenon remains elusive. The aim of this study was to determine the significance of apoptosis as a mediating factor in cardiac function following chronic high alcohol versus low alcohol exposure. Adult rats were provided 5 mM (low alcohol), 100 mM (high alcohol) or pair-fed non-alcohol controls for 4–5 months. The hearts were dissected, sectioned and stained with cresyl violet or immunohistochemically for caspase-3, a putative marker for apoptosis. Cardiomyocytes were isolated to determine the effects of alcohol exposure on cell contraction and relaxation. High alcohol animals displayed a marked thinning of the left ventricular wall combined with elevated caspase-3 activity and decreased contractility. In contrast, low alcohol was associated with increased contractility and decreased apoptosis suggesting an overall protective mechanism induced by low levels of alcohol exposure.

Abstract 158: What’s the Nrf Got To Do With Alcoholic Cardiomyopathy?

The beneficial cardiovascular effects of low alcohol consumption are becoming more clinically evident. This is in sharp contrast with the detrimental ones associated with heavy alcohol drinking. We have previously shown that cardiac inotropy is closely related to the activation of the survival PI3K/Akt pathway. The objective of this study was to assess the role of the PI3K/Akt pathway in mediating the inotropic effects of chronic alcohol consumption. Littermate adult rats were put on a 3-months isocaloric Lieber-Decarli liquid diet with either low alcohol (LA: 5mM) or high alcohol (HA: 100mM) levels. The measured final blood alcohol concentrations were 0.02% and 0.46% respectively. In vivo intra-ventricular catheterization (Scisense/iWorks) of the left ventricle (LV) showed that an improved LV contractility (ESPVR and PRSW) of the LA group while the opposite occurred with the HA group. The alterations in contractility were independent of the afterload as in vitro cellular and sarcomeric inotropic measurements (Ionoptix) showed similar profile to the LV in vivo data. These functional LA effects were correlated with reduced H 2 O 2 levels (as well as SOD-3 activity) and enhanced Akt, NFκB, FOXO-1 and NRF1/2 gene expressions which translated into higher NRF2 protein levels and cardiocyte survival. On the contrary, HA increased H 2 O 2 level (as well as SOD-3 activity) and reduced the Akt, NFκB, FOXO-1 and NRF1/2 gene expressions which translated into lower NRF2 protein levels and cardiocyte survival. In addition, we observed dampening of caspase-3/7 activity with HA which was not affected with LA. We conclude that the improved low alcohol-induced cardiac inotropic function may be mediated through reduction of oxidative stress via Akt/NRF2 activation, which showed opposite expressions with the detrimental high alcohol effects. We also note that cell death occurrences may turn to necrotic pathways as alcohol exposure increases beyond LA levels.