Molecular and cellular events in alcohol-induced muscle disease.

Alcohol consumption induces a dose-dependent noxious effect on skeletal muscle, leading to progressive functional and structural damage of myocytes, with concomitant reductions in lean body mass. Nearly half of high-dose chronic alcohol consumers develop alcoholic skeletal myopathy. The pathogenic mechanisms that lie between alcohol intake and loss of muscle tissue involve multiple pathways, making the elucidation of the disease somewhat difficult. This review discusses the recent advances in basic and clinical research on the molecular and cellular events involved in the development of alcohol-induced muscle disease. The main areas of recent research interest on this field are as follows: (i) molecular mechanisms in alcohol exposed muscle in the rat model; (ii) gene expression changes in alcohol exposed muscle; (iii) the role of trace elements and oxidative stress in alcoholic myopathy; and (iv) the role of apoptosis and preapoptotic pathways in alcoholic myopathy. These aforementioned areas are crucial in understanding the pathogenesis of this disease. For example, there is overwhelming evidence that both chronic alcohol ingestion and acute alcohol intoxication impair the rate of protein synthesis of myofibrillar proteins, in particular, under both postabsorptive and postprandial conditions. Perturbations in gene expression are contributory factors to the development of alcoholic myopathy, as ethanol-induced alterations are detected in over 400 genes and the protein profile (i.e., the proteome) of muscle is also affected. There is supportive evidence that oxidative damage is involved in the pathogenesis of alcoholic myopathy. Increased lipid peroxidation is related to muscle fibre atrophy, and reduced serum levels of some antioxidants may be related to loss of muscle mass and muscle strength. Finally, ethanol induces skeletal muscle apoptosis and increases both pro- and antiapoptotic regulatory mechanisms.

Up-regulation of myocardial L-type Ca2+ channel in chronic alcoholic subjects without cardiomyopathy.

BACKGROUND: Excessive ethanol intake is one of the most frequent causes of acquired dilated cardiomyopathy in developed countries. L-type Ca(2+) channels, involved in excitation-contraction coupling, are disturbed in animal models of persistent ethanol consumption. This study was designed to evaluate the density and function of myocardial L-type Ca(2+) channel receptors in organ donors with chronic alcoholism and controls. METHODS: The protein expression of L-type Ca(2+) channels was determined with (3)H-(+)-PN 200-110-binding experiments using a specific antibody against the alpha(1)-subunit in homogenate samples of left-ventricle apex from organ donors: healthy controls (n=11), chronic alcoholic without cardiomyopathy (n=12), and alcoholics with cardiomyopathy (n=11). Morphometric measurements of cardiomyocytes were performed. RESULTS: Binding experiments proved an up-regulation of L-type Ca(2+) channels expression in alcoholic patients compared with controls (B(max) 2.61 +/- 1.10 vs 1.33 +/- 0.49 fmol/mg, respectively; p<0.001). This up-regulation was present in the group of alcoholic subjects without cardiomyopathy, and was not seen in those with cardiomyopathy (3.39 +/- 2.20 vs 1.77 +/- 0.53 fmol/mg, respectively; p=0.02). The cross-sectional area and perimeter of the cells were greater in alcoholic patients with cardiomyopathy compared with controls and alcoholic patients without cardiomyopathy (500 +/- 87 vs 307 +/- 74 and 255 +/- 25 microm(2), respectively; p<0.001 both) as was the perimeter (78.7 +/- 7.7 vs 61.5 +/- 7.2 and 56.5 +/- 2.8 microm, respectively; p<0.001 both). Binding results did not change after adjusting receptor measurements for cross-sectional area and cell perimeter. CONCLUSIONS: Chronic alcoholism causes an up-regulation of myocardial L-type Ca(2+) channel receptors, which decreases when cardiomyopathy is present.

Varón de 52 años con cervicalgia y síntomas neurológicos en las extremidades superiores / Cervical pain and neurological symptoms in upper limbs in a 52-year-old man

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Evidence of apoptosis in alcoholic cardiomyopathy.

Apoptosis is a mechanism of cell death implicated in the pathogenesis of alcohol-induced organ damage. Experimental studies have suggested alcohol-mediated apoptosis in the cardiac muscle, and there is evidence of skeletal muscle apoptosis in long-term high-dose alcohol consumers. The relation between skeletal and cardiac muscle damage in alcoholism led us to consider the pathogenic role of apoptosis in alcoholic dilated cardiomyopathy. We evaluated apoptosis in the hearts of individuals with long-term alcoholism (n = 19), of those with long-standing hypertension (n = 20), and of those with no known disease as control subjects (n = 7). Alcohol consumption measurement, heart function evaluation, and myocardial immunohistochemical and morphometric analysis were performed. Apoptosis was evaluated with deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end-labeling assay, and BAX and BCL-2 expressions were used to detect induction of and protection from proapoptotic mechanisms, respectively. Hearts from patients with a history of alcoholism showed apoptotic indexes similar to those of organs from hypertensive donors. Subjects with structural heart damage of alcoholic or hypertensive origin showed higher apoptotic indexes in deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end-labeling, BAX, and BCL-2 assays as compared with control subjects (P < .001 for all). Moreover, New York Heart Association class I alcoholic patients displayed higher BAX and BCL-2 expressions as compared with control subjects. We conclude that apoptosis is present to a similar degree in the heart muscle of high-dose alcohol consumers and long-standing hypertensive subjects and is related to structural damage. Proapoptotic mechanisms are activated in alcoholic patients without heart damage.

Myocardial antioxidant status in chronic alcoholism.

BACKGROUND: Excessive ethanol intake is one of the most frequent causes of acquired dilated cardiomyopathy in developed countries. The pathogenesis is multifactorial, with the antioxidant imbalance of cardiac muscle being a potential factor. The current study evaluates myocardial antioxidant status in ethanol consumers and its relation to cardiac damage. METHODS: The authors assessed superoxide dismutase, glutathione peroxidase, and glutathione reductase enzyme activities as well as the total antioxidant status capacity in myocardial samples obtained from organ donors with sudden death of traumatic or neurological origin. They studied 23 high-dose chronic alcohol consumers, 27 individuals with long-standing hypertension, and 11 healthy controls. Cardiomyopathy was defined according to standard functional and histological criteria. RESULTS: Patients with dilated cardiomyopathy, either of alcoholic or hypertensive origin, showed increased myocardial superoxide dismutase activities compared with patients without cardiomyopathy (p < 0.001, both) and controls (p < 0.05, both). Total antioxidant status capacity and the activity of glutathione peroxidase and glutathione reductase enzymes were similar in all groups. Superoxide dismutase activity was related to the presence of cardiac enlargement and the degree of cardiac histological damage. The amount and type of alcoholic beverages as well as the nutritional status of the patients were not related to myocardial antioxidant activity. CONCLUSIONS: The presence of dilated cardiomyopathy, of either alcoholic or hypertensive origin, is related to an increase in myocardial superoxide dismutase activity.

Influence of nutritional status on alcoholic myopathy.

BACKGROUND: Muscle weakness and structural changes in striated skeletal muscle are common in persons with chronic alcoholism. OBJECTIVE: The objective of the study was to assess the role of malnutrition in the development of chronic alcoholic myopathy. DESIGN: We prospectively evaluated 146 men who reported an intake >/=100 g ethanol/d for the previous 5 y and 73 well-nourished control subjects. Alcohol consumption, energy and protein nutritional status, and deltoid muscle strength were determined. Deltoid muscle tissue specimens were taken from alcoholics and from 14 control subjects for histochemical studies and morphometric measurements of the fibers. RESULTS: Deltoid muscle strength was less in alcoholics than in control subjects (P < 0.001). Muscle strength correlated with lifetime consumption of ethanol (r = -0.56, P < 0.001), and a decrease in muscle strength was significantly greater in the presence of energy malnutrition. Using logistic regression analysis, we observed that alcoholics with muscle strength < 18 kg had the independent risk factors of an arm muscle area < 50 cm(2) (odds ratio: 5.4; 95% CI: 2.3, 12.3), consumption of > 1600 kg ethanol throughout their lives (odds ratio: 4.5; 95% CI: 2.0, 10.1), and protein malnutrition (odds ratio: 4.2; 95% CI: 1.4, 12.7). Protein malnutrition was also associated with muscle inefficiency (P < 0.001). Histologic myopathy was present in 58% of alcoholics, was related to lifetime ethanol consumption (P = 0.001), and was more severe in the presence of protein malnutrition (P = 0.01). CONCLUSION: Malnutrition is an additional developmental factor in the functional and structural muscle damage induced by chronic ethanol consumption.