Effect of Threonine Deficiency on Changes in Enzyme Activity and Liver Fat Deposition with Time

Abstract

Albino rats were fed a low protein diet (9% casein) deficient in threonine. The activities of several enzyme systems were measured at intervals over a period of 43 days. Control rats were fed the same diet supplemented with 0.36% of DL-threonine. The deposition of liver fat in the threonine deficient rats reached a peak in 24 days. After 6 weeks the level of fat in the livers of these rats had fallen to approximately half of this maximum. The activities of two enzyme systems, xanthine oxidase and malic dehydrogenase, varied with time. The maximum decrease in activity of these systems in the threonine deficient group, as compared with the control, occurred on the 19th day of the experiment. This phase of decreasing activity was followed by a period of recovery. The fat was not mobilized out of the livers of the threonine deficient rats until after the enzymes had begun to recover.