In your favor
Alcohol Clin Exp Res. 2004 Apr;28(4):517-25.
Restoration of protein synthesis in heart and skeletal muscle after withdrawal
of alcohol.
Vary TC, Nairn AC, Lang CH.
Department of Cellular and Molecular Physiology, The Pennsylvania State
University College of Medicine, Hershey, Pennsylvania 17033, USA.
tvary@psu.edu
BACKGROUND: The rate of protein synthesis is diminished after chronic alcohol
consumption through changes in both mRNA translation initiation and elongation.
It remains unknown how long adverse effects of alcohol on protein synthesis
persist after withdrawal from ethanol. METHODS: We examined the effect of
removal of alcohol from the diet of rats for 72 hr after chronic alcohol
exposure (16 weeks) on rates of protein synthesis and potential mechanisms for
controlling mRNA translation in heart, skeletal muscle, and liver. Rates of
protein synthesis were measured after intravenous infusion of
[3H]-l-phenylalanine. The formation of active eukaryotic initiation factor
(eIF)4E.eIF4G complex, the cellular content of eukaryotic elongation factor
(eEF)1A and eEF2, and the phosphorylation state of eEF2 and S6K1 were measured
in each tissue. RESULTS: Withdrawal of alcohol from the diet restored protein
synthesis in heart and skeletal muscle to values obtained in pair-fed control
rats not exposed to alcohol. However, the organ weight and protein content per
muscle was not affected by withdrawal of alcohol from the diet. In both heart
and skeletal muscle, the restoration of protein synthesis correlated with
reversal of defects in the formation of active eIF4E.eIF4G complex and eEF1A
content. Myocardial eEF2 content was also restored to control values after
withdrawal of alcohol from the diet. In the gastrocnemius, there was a decrease
in the cellular content of eEF2. The lower eIF2 content may have been
counterbalanced by an increased activity of eEF2 through a reduction in the
phosphorylation state of eEF2 allowing protein synthesis to proceed unimpeded.
CONCLUSIONS:
These studies indicate that changes in protein metabolism observed
during chronic alcohol intake are reversible and do not, at this stage,
represent an irreversible change in cardiac or skeletal muscle.
