Aminotransferase activity in the liver of diabetic mice.

Enzyme activity in the livers of mice was studied in examining the metabolic disturbances of diabetes. Spontaneously non-obese diabetic (NOD) mice, mice with alloxan-induced diabetes (Allo), and control ICR mice were used. As NOD mice undergo a spontaneous pathogenic process over time, younger and older NOD mice were compared (non-diabetic and diabetic) as were control ICR mice. Two liver enzymes became more active with age, aspartate aminotransferase (AST) and alanine aminotransferase (ALT). AST activity increased more in the hyperglycemic mice, i.e., the diabetic NOD and the Allo mice, than in the normoglycemic group, i.e., the ICR and non-diabetic NOD mice. Abnormally high AST activity was seen in the cytosolic fraction of the liver but not in the mitochondrial fraction. The changes in enzyme activity in diabetic mice were independent of any age-associated changes. The higher AST levels in diabetic mice are thought to be consistent with their greater need for gluconeogenic substrate. AST showed a more notably higher increase than did ALT in this study, and lactate dehydrogenase showed no significant changes.