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The objective of this study was to assess the essential fatty acid status of patients with anorexia nervosa. Blood was collected from eight fasting female anorexia nervosa patients with a mean of 81% ideal body weight. Fatty acid composition of phospholipids, nonesterified fatty acids, triglycerides and cholesteryl esters of plasma were determined by capillary gas chromatography to indicate polyunsaturated fatty acids status compared with 19 healthy female adults < 25 y old. Subjects with anorexia nervosa showed polyunsaturated fatty acid deficiencies in plasma phospholipids different from simple nutritional essential fatty acid deficiency or chronic malnutrition. The phospholipid profile showed significantly lower (n-6) and (n-3) elongation and desaturation products, and elevated short-chain saturated, short-chain monounsaturated, branched-chain and odd-chain fatty acids. These elevations indicate enhancement of biosynthesis of alternative fatty acids that only partially compensated for the loss of polyunsaturated fatty acids in providing membrane "fluidity." Calculated mean melting point of the fatty acids of phospholipids in patients with anorexia nervosa was elevated 7.7 degrees C above normal values. These results demonstrate that patients with anorexia nervosa have deficiencies of selected essential fatty acids, compensatory changes in nonessential fatty acids and decreased fluidity of plasma lipids.

3T3-L1 fibroblasts have limited enzymatic capacity to oxidize valine. Enzymes expressed in these cells allow efficient oxidation of only the first carbon of this branched chain amino acid. The pathway is effectively truncated at the level of 3-hydroxyisobutyrate because of very low expression of two enzymes required for the complete pathway, 3-hydroxyisobutyrate dehydrogenase and methylmalonate semialdehyde dehydrogenase. These two enzymes, as well as the branched chain alpha-ketoacid dehydrogenase, are markedly induced upon differentiation of 3T3-L1 fibroblasts into adipocytes. Flux through the first two decarboxylation steps of valine catabolism is increased dramatically after differentiation, particularly through the step catalyzed by methylmalonate semialdehyde dehydrogenase. Activation of the distal portion of the valine catabolic pathway correlates with significant increases in enzyme protein and mRNA levels for 3-hydroxyisobutyrate dehydrogenase and methylmalonate semialdehyde dehydrogenase, and this establishes the pathway in 3T3-L1 adipocytes for utilization of valine carbon for lipogenesis. The induction profiles of 3-hydroxyisobutyrate dehydrogenase and methylmalonate semialdehyde dehydrogenase are very similar, suggesting coordinate regulation of the expression of these two valine pathway-specific enzymes. Induction of valine catabolism in 3T3-L1 cells is solely differentiation dependent, suggesting regulation by the same factors that govern differentiation of 3T3-L1 fibroblasts into adipocytes.

Ethanol inhibited glucose synthesis from alpha-ketoisovalerate by isolated rat hepatocytes without significant inhibition of flux through the branched-chain alpha-ketoacid dehydrogenase complex. Accumulation of 3-hydroxyisobutyrate, an intermediate in the catabolism of alpha-ketoisovalerate, was increased by ethanol, indicating inhibition of flux at the level of 3-hydroxyisobutyrate dehydrogenase. 3-Hydroxybutyrate caused the same effects as ethanol, suggesting inhibition was a consequence of an increase in the mitochondrial NADH/NAD+ ratio. Flux through the 3-hydroxyisobutyrate dehydrogenase was more sensitive to regulation by the mitochondrial NADH/NAD+ ratio than flux through the branched-chain alpha-ketoacid dehydrogenase. Oleate also inhibited glucose synthesis from alpha-ketoisovalerate, but marked inhibition of flux through the branched-chain alpha-ketoacid dehydrogenase complex was caused by this substrate.