Effect of Vitamin B6 Deficiency on Tissue Dehydrogenases and Fat Synthesis in Rats

Abstract

The activities of glutamate (GDH), lactate (LDH), isocitrate (ICDH), malate (MDH), and glucose-6-phosphate (G6PDH) dehydrogenases were measured in liver, adipose tissue, and renal cortex and medulla homogenates from control and vitamin B6-deficient rats. G6PDH and LDH were significantly decreased in liver homogenates from deficient animals when compared to both ad libitum and pair-fed controls. Significant increases in all five enzymes were seen in adipose tissue homogenates from deficient rats only when compared to ad libitum controls. Except for an increase in kidney cortex G6PDH no significant changes were found in kidney enzymes of deficient rats. Insulin administration partially reversed the decreases in liver G6PDH and LDH activities. There were no significant differences in the ability of liver slices from fasted ad libitum-fed control and deficient rats to synthesize lipid from glucose or acetate. In fed animals synthesis of liver lipids from glucose but not acetate was significantly higher in slices from deficient rats. These data indicate that although carcass levels of fat are especially low in vitamin B6-deficient rats, their liver and adipose tissue may have a greater than normal capacity to synthesize fat when glucose is metabolically available in sufficient quantities.