Effect of vitamin A depletion on stress-induced change in urinary output of catecholamines

The effect of vitamin A depletion on stress-induced change in sympathoadrenal medullary activity was studied in rats. Four consecutive hours daily of immobilization provoked a marked increase in urinary excretion of free norepinephrine (NE) and epinephrine (E), confirming previous findings. The stress caused a significant decrease in output of free dopamine (DA). In contrast, the vitamin A-depleted rats in the resting state excreted threefold more NE in urine as compared with the normal animals. The urinary NE response to the stress was markedly diminished in the depleted rats, although E and DA responses to the stress were similar in magnitude to those in the normal animals. These results suggest that vitamin A depletion causes derangement of the neurosympathetic system; hence, the animals cannot appropriately respond to the stress. Alternatively, the state of vitamin A depletion may be fact a stress, and in consequence the animals have already been in a state of maximal response before immobilization.