Influence of Thyroid on Radiophosphorus Metabolism in Fish

Abstract

INFORMATION concerning the endocrinological regulation of mineral metabolism in fishes is lacking. The problem is particularly interesting because the parathyroid gland which regulates the normal calcium and phosphorus content within the body in higher vertebrates is supposed to be absent in fishes. I have tried to find out if the thyroid had any control over the mineral metabolism in yearling salmonr Salmo solarL.^1,2. Since surgical thyroidectomy is not possible in fishes, an attempt was made to destroy the thyroid follicles by anti-thyroid drugs. Successful destruction could not be achieved since the fishes were treated with thiourea for a very short time. The result of the experiments suggested that when fish were treated with thiourea for a short time, thyroid was indirectly stimulated by thyrotropin secreted by the pituitary and so the uptake of phosphorus-32 was more than in the controls ; in thyroxine-injected fish the uptake was a maximum because the stimulation was direct.