The cyclic pattern of blood alcohol levels during continuous ethanol feeding in rats: the effect of feeding S-adenosylmethionine

Abstract

S-adenosylmethionine (SAMe), the major methyl donor for DNA and histone methylation was fed with ethanol for 1month in order to modify the effects of ethanol on rat liver. The following parameters were studied to determine the effects of SAMe; liver histology, the blood alcohol cycle (BAL), changes in gene expression mined from microarray analysis, changes in histone methylation, changes in liver SAMe levels and its metabolites and ADH. SAMe changed the type of fatty liver, reduced liver ALT levels and prevented the BAL cycle caused by intragastric ethanol feeding. Microarray analysis showed that SAMe feeding prevented most of the changes in gene expression induced by ethanol feeding, presumably by inducing H3K27me3 and gene silencing. H3K27me3 was significantly increased by SAMe with or without ethanol feeding. It is concluded that SAMe feeding stabilized global gene expression so that the changes in gene expression involved in the blood alcohol cycle were prevented.

Figure 1

Figure 1A. Liver sections were stained with hematoxylin and eosin. Hepatocytes from rats fed ethanol only showed macrovesicular steatosis (x130). Hepatocytes from rats fed ethanol plus SAMe showed microvesicular steatosis (x130). Magnification of inserts was x 260. Hepatocytes from rats fed dextrose showed normal liver without steatosis (x130). Hepatocytes from rats fed SAMe alone, showed normal liver without steatosis (x130) Figure 1B. Morphometric quantitation of liver fat. Ethanol fed alone caused a marked increase in fat, significantly greater than the 3 other groups of rats (Mean±SEM n=3 p<0.05). Ethanol fed with SAMe caused less steatosis but significantly more than the two controls (Mean±SEM, n=3, p<0.05).

Figure 1

Figure 1A. Liver sections were stained with hematoxylin and eosin. Hepatocytes from rats fed ethanol only showed macrovesicular steatosis (x130). Hepatocytes from rats fed ethanol plus SAMe showed microvesicular steatosis (x130). Magnification of inserts was x 260. Hepatocytes from rats fed dextrose showed normal liver without steatosis (x130). Hepatocytes from rats fed SAMe alone, showed normal liver without steatosis (x130) Figure 1B. Morphometric quantitation of liver fat. Ethanol fed alone caused a marked increase in fat, significantly greater than the 3 other groups of rats (Mean±SEM n=3 p<0.05). Ethanol fed with SAMe caused less steatosis but significantly more than the two controls (Mean±SEM, n=3, p<0.05).

Figure 2

A. Graph showing that ethanol feeding caused a cyclic increase, and decrease, in the UAL 6 day cycle over a 6–7 day period.(n=3). B. Graph showing the absence of the UAL cycle in the group of rats (n=3) fed both ethanol plus SAMe.

Figure 3

A. SAMe levels were lower in the livers of rats fed ethanol and rats fed ethanol plus SAMe (Mean±SEM, n=3). B. SAH levels in the liver were lower in the 3 experimental groups of rats compared to the dextrose controls (Mean±SEM, n=3). C. SAM/SAH ratios of the four groups of rats show that ethanol alone caused a decrease in the ratio when compared to rats fed Dextrose plus SAMe (Mean±SEM, n=3). D. MTA levels were reduced in the livers of the 3 rat treatment groups, compared to the control rats fed dextrose.

Fig 4

KEGG functional pathways changed by ethanol feeding compared with the dextrose controls (n=3). Important functional pathways affected include adipocytokine, cytokine-cytokine receptor interaction, MAPK, cytochrome P450s, PPAR, TGFβ, and Toll-like receptor signaling pathways.

Fig 5

KECG functional pathways changed by feeding ethanol plus SAMe compared with the dextrose controls (n =3). Note that many pathway changes have been reduced by SAMe treatment.

Figure 6

Western blots showed that ADH levels were significantly over expressed when rats were fed ethanol. Feeding SAMe did not prevent this ((Mean±SEM, n=3).

Figure 7

A. Western blots show that SAMe feeding increased the levels of H3K27me3 with or without ethanol. (Dex+SAMe vs Dex= p<0.01; SAMe+ETOH vs Dex= p<0.008; Dex+SAMe vs EtoH= p<0.05; SAMe EtoH vs ETOH= p<0.03, Mean±SEM, n=3. B. Western blots show that the levels of H3K4me3 were unchanged by feeding ethanol and/or SAMe.