Chronic ethanol feeding increases 7-hydroperoxycholesterol and oxysterols in rat skeletal muscle

It was our hypothesis that, as a consequence of increased oxidative stress, cholesterol-derived hydroperoxides and oxysterols are increased in skeletal muscles chronically exposed to ethanol. To test this we fed male Wistar rats (0.1 kg initial body weight) a nutritionally complete liquid diet containing ethanol as 35% of total calories: controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. At the end of 1 1/2 months, soleus (type I fiber-predominant) and plantaris (type II fiber-predominant) skeletal muscles were dissected out. We measured 7alpha- and 7beta-hydroperoxycholest-5-en-3beta-ol (7alpha-OOH and 7beta-OOH), as well as 7alpha- and 7beta-hydroxycholesterol (7alpha-OH and 7beta-OH), and 3beta-hydroxycholest-5-en-7-one (also termed 7-ketocholesterol; 7-keto). We identified and confirmed by LC-MS the presence of 7alpha-OOH, 7beta-00H and 7alpha-OH, 7beta-OH and 7-keto in skeletal muscle of rats. We also showed that in response to chronic alcohol feeding, there were significant increases in soleus 7alpha-OH (P =.0005), beta-OH (P =.0005), and 7-keto (P =.0007). In the plantaris, mean 7alpha-OH and 7-keto were not significantly altered (P >.05), but 7beta-OH increased (P =.04118). This is the first report of 7alpha-OH, 7beta-OH, and 7-keto oxysterols being identified in skeletal muscle of rats. Their elevation in chronic experimental alcoholism, together with increases in cholesterol hydroperoxides, may possibly represent evidence of increased oxidative stress. Copyright 2002, Elsevier Science (USA), All rights reserved.