Ascorbic acid-thyroxine interrelationship in cold acclimation.

Abstract

Experiments were designed to find whether ascorbic acid administration had any effect on the following parameters of metabolic alteration in cold-exposed animals: oxygen consumption, thyroxine secretory rate (TSR) and biosynthesis of ascorbic acid. The results obtained may be summarized as follows: (1) No effect of ascorbic acid on the metabolic rate could be detected. (2) In untreated animals the TSR is increased during the first week of cold exposure, returns to normal in the following weeks and rises again after ten weeks. In the treated animals the TSR is also increased during the first week of cold exposure, but significantly less so than in the untreated animals. No effect of ascorbic acid is observable at room temperature. (3) The rate of biosynthesis of ascorbic acid is not altered significantly during the first three weeks of cold exposure, neither in the treated nor in the untreated animals. After six weeks of continuous exposure to cold, the rate of biosynthesis is significantly increased in untreated animals; this increase is prevented by the administration of ascorbic acid. These results are discussed along with the current literature and it is concluded that the effect of ascorbic acid in cold exposed animals could be partly explained by a lowering of the requirements for thyroid hormones. Cellular mechanisms of this action are briefly discussed and avenues of future research pointed out.