Influence of galactoflavin and inanition on the adrenal ascorbic acid response to stress in rats.

Abstract

Rats on a riboflavin-deficient diet containing the riboflavin antagonist, galactoflavin, lost the ability to respond to the stress of unilateral adrenalectomy, as measured by the decrease in ascorbic acid (AAA) in the contralateral adrenal. This impairment was noted in 10 days at an initial body weight of 80 gm., 22 days at 100 gm., and 35 days at 200 gm. Additional stresses such as loss of the tail and removal of 0.5 ml of blood were likewise incapable of causing a decrease in AAA in the deficient animals. However, extensive laparotomy did result in a decrease in AAA, suggesting that the pituitary-adrenocortical system in these animals was still responsive to severe stress. The impairment in adrenal response was noted in rats maintained on both high carbohydrate and high protein diets containing galactoflavin and deficient in riboflavin. However, pair-weighed controls receiving a complete, galactoflavin- free diet also exhibited an impaired response. Riboflavin injection before unilateral adrenalectomy did not restore the response of the deficient animals. Feeding a complete diet for two days to riboflavin-deficient rats restored the response as did ad libitumfeeding of the riboflavin-deficient diet to pair-weighed control rats for three days. Weanling rats placed on high carbohydrate riboflavin - deficient diets for 82 days gave a significant decrease in AAA to unilateral adrenalectomy. Although unpublished results from this laboratory and published results by Forker and Morgan indicate that riboflavin is essential for the release of AAA under certain conditions, the data in this paper suggest that dietary factors other than riboflavin may be more important in the AAA response to stress.