In summary, these new data support the hypothesis that the
mitochondrion is a central player in SAM hepato-protection. We
show that SAM prevents alcohol-induced hypoxia, normalizes responsiveness
for MPT pore induction, and prevents increased
sensitivity to NO-mediated inhibition of respiration. As these SAMmediated
responses mirror those seen using the iNOS knockout
mouse model [25,39], it is likely that NO and/or other RNS derived
from iNOS mediate the damaging effects of alcohol on the mitochondrion.
And, while we cannot determine from the current
data whether the protective effect of SAM derives directly from
blunting NO (or RNS)-mediated toxic reactions, we do know from
previous work that SAM prevents iNOS induction [13]. Thus, we
speculate that SAM prevents alcohol-induced mitochondrial damage
by blocking iNOS induction in the liver. Although pre-clinical
data like those included herein show hepato-protective actions of
SAM early in the disease process, the effectiveness of SAM in
treating end-stage liver disease patients with alcoholic cirrhosis is
mixed [66,67]. However, as reviewed by Anstee and Day [68], only
a handful of small clinical trials have been performed to assess the
efficacy of SAM in treating a variety of liver diseases. Therefore,
targeting methyl metabolism with SAM or related agents still remains
a viable therapy for treating alcoholic liver disease.