Folate deficiency is the most common sign of malnutrition in chronic alcoholic patients, affecting nucleic acid synthesis and turnover of all cells. On the basis of prior studies in chronic alcohol-fed primates, which showed decreased folate absorption and hepatic uptake with increased urinary folate excretion, we propose 1) that chronic alcoholism leads to physical and chemical changes in membranes involved in folate transport. Alternatively, 2) free radical production during ethanol metabolism could accelerate the catabolism of endogenous folates. During the first period of this grant we established a model of control and alcohol feeding in the miniature pig and found a significant reduction in the activity of jejunal brush border folate hydrolase with decreased in vivo hydrolysis of pteroylpolyglutamate (PteGlun), the principal dietary folate. We also found striking changes in the molar ratios of circulating phospholipid fatty acids, which were partly reflected by the fatty acid composition of the jejunal brush border membrane and which were consistent with a defect in fatty acid desaturation. In the proposed renewal, we plan to test the two hypotheses for folate deficiency in pigs fed a higher concentration of ethanol for a minimum of two to three years. Membrane effects, including changes in lipid composition and order parameter will be measured at 4 to 6 month intervals in plasma and tissue biopsies and hepatic microsomal fatty acid desaturase will be isolated and studied in control and alcoholic groups. After killing, the transport of monoglutamyl folate (PteGlu) will be measured in intestinal hepatic, and renal tubular membranes, correlating changes with membrane microviscosity and lipid composition. The effect of chronic alcoholism on the mucosal synthesis and intracellular processing of jejunal brush border folate hydrolase will be studied by mRNA hybridization and by immunoprecipitation of nascent proteins in mucosal explant cultures. Injecting trace amounts of 3H-PteGlu to label endogenous folates in timed liver biopsies, we will measure the effect of chronic alcohol feeding in vivo on the uptake intracellular binding, and metabolism of folate in the liver. In separate experiments with 14C and 3H doubly labeled PteGlu we will determine whether chronic alcoholism accelerates the catabolism and urinary excretion of folate catabolites. These quantitative data will be correlated with studies of hepatic trace mineral and free radical formation and metabolism in both groups of animals. The proposed studies will identify etiologies for folate deficiency in chronic alcoholism. Using folate as an example, these studies will further understanding of the interactions among chronic alcoholism, membrane changes, nutrient metabolism, and malnutrition.

Agency
National Institute of Health (NIH)
Institute
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Type
Research Project (R01)
Project #
5R01AA006938-05
Application #
3110399
Study Section
Biochemistry, Physiology and Medicine Subcommittee (ALCB)
Project Start
1986-04-01
Project End
1994-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
5
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
Schools of Medicine
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
Niemela, O; Parkkila, S; Pasanen, M et al. (1999) Induction of cytochrome P450 enzymes and generation of protein-aldehyde adducts are associated with sex-dependent sensitivity to alcohol-induced liver disease in micropigs. Hepatology 30:1011-7
Parkkila, S; Halsted, C H; Villanueva, J A et al. (1999) Expression of testosterone-dependent enzyme, carbonic anhydrase III, and oxidative stress in experimental alcoholic liver disease. Dig Dis Sci 44:2205-13
Halsted, C H; Villanueva, J; Chandler, C J et al. (1996) Ethanol feeding of micropigs alters methionine metabolism and increases hepatocellular apoptosis and proliferation. Hepatology 23:497-505
Niemela, O; Parkkila, S; Yla-Herttuala, S et al. (1995) Sequential acetaldehyde production, lipid peroxidation, and fibrogenesis in micropig model of alcohol-induced liver disease. Hepatology 22:1208-14
Villanueva, J; Chandler, C J; Shimasaki, N et al. (1994) Effects of ethanol feeding on liver, kidney and jejunal membranes of micropigs. Hepatology 19:1229-40
Niemela, O; Parkkila, S; Yla-Herttuala, S et al. (1994) Covalent protein adducts in the liver as a result of ethanol metabolism and lipid peroxidation. Lab Invest 70:537-46
Halsted, C H; Villanueva, J; Chandler, C J et al. (1993) Centrilobular distribution of acetaldehyde and collagen in the ethanol-fed micropig. Hepatology 18:954-60
Nakamura, M T; Tang, A B; Villanueva, J et al. (1992) Reduced tissue arachidonic acid concentration with chronic ethanol feeding in miniature pigs. Am J Clin Nutr 56:467-74
Chandler, C J; Harrison, D A; Buffington, C A et al. (1991) Functional specificity of jejunal brush-border pteroylpolyglutamate hydrolase in pig. Am J Physiol 260:G865-72
Zidenberg-Cherr, S; Halsted, C H; Olin, K L et al. (1990) The effect of chronic alcohol ingestion on free radical defense in the miniature pig. J Nutr 120:213-7

Showing the most recent 10 out of 13 publications