| Abstract: | Thyrotropin releasing hormone (TRH), in a dose of 0.01 and 1.0  g/ml, sharply increased cytochrome oxidase activity in the adenohypophysis of rats fed for 6 weeks with methylthiouracil. This effect of TRH on enzyme activity was blocked by thyroxine (T4), if added to the incubation medium in a concentration of 20 g/ml. Actinomycin D (20 g/ml) prevented the blocking of cytochrome oxidase by T4. TRH in a concentration of 0.01 g/ml and T4, in a dose of 2.0 g/ml, caused no change in cytochrome oxidase activity in the adenohypophysis of intact and partially thyroidectomized rats.Laboratory of Biological Standardization of Hormones, Institute of Experimental Endocrinology and Hormone Chemistry, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 11, pp. 559–562, November, 1977. |
