Circadian Variation in Rat Plasma Zinc and Rapid Effect of Dietary Zinc Deficiency

Abstract

Adult rats on a 12-hr light/dark schedule fed a complete diet exhibited a circadian variation in plasma zinc, with a sharp decline of 25% between 8 and 12 hr after the beginning of the light cycle. In rats fed a zinc-deficient diet for 24 hr, plasma zinc concentration was similar to that of controls for the first 12 hr, but continued to fall further, and was significantly lower than controls after 14 hr. When rats were fed the zinc-deficient diet beginning at 8 hr of the light cycle, their plasma zinc concentration was significantly reduced 6 hr later. The results demonstrate the rapid effect of dietary zinc deficiency.