抄録
Reduced pyridine nucleotides in in situ thyroid was measured directly and continuously by means of a microfluorometer devised specifically for this particular purpose, and the effects of thyrotropin on the level of these nucleotides were examined. Thyrotropin given intravenously to thyroxine-treated rabbits and rats caused a prompt and sustained fall in the level of reduced pyridine nucleotides in thyroid. The minimal doses for this effect were 0.1U in rabbits and 0.02U in rats. Bovine serum albumin, growth hormone, insulin, glucagon, corticotropin, luteinizing hormone, prolactin, and parathyroid hormone did not reproduce the thyrotropin effect. Follicle stimulating hormone, in large amounts, induced an inconsistent and minor oxidative response. Thyrotropin did not affect kidney, testis, or parathyroid pyridine nucleotides. Such oxidative shift of thyroid redox-state of pyridine nucleotides as produced by thyrotropin was mimicked by Dicoumarol or by a long-acting thyroid stimulator. 3', 5'-cyclic AMP or dibutyryl cyclic AMP, on the other hand, led to a reductive shift of the thyroid redox-state.
From these results, a possibility is discussed that thyrotropin in vivo acts on thyroid to result, independently of adenyl cyclase activation, in oxidation of reduced pyridine nucleotides.
