ACTH CONTENT IN THE NEUROHYPOPHYSIS OF RAT

Abstract

1. ACTH activity of anterior and posterior lobe extracts obtained from adult male rats was determined by the in vitro method of SAFFRAN and SCHALLY and by the method of SAYERS et al.
2. In case ACTH activity was measured by the in vitro method, the activity of the anterior lobe was 1242±101mU per gland and 283±21.0mU per mg fresh tissue, and that of the posterior lobe 53±4.8mU per gland and 88±7.6mU per mg.
3. Markedly less activity was obtained by the method of SAYERS: 1mU standard ACTH activity was equivalent to 10.7mU anterior lobe extract and 7.6 mU posterior lobe extract as determined by the in vitro method.
4. Pitressin in doses used in the present experiments had no effect on rat adrenal tissue in vitro in releasing corticosterone, nor potentiating the activity of ACTH added together. Pitressin did not cause any depletion in adrenal ascorbic acid concentration in hypophysectomized rats, nor potentiate ACTH activity of the anterior lobe extract.
5. Brain extracts did not show any ACTH activity in vitro.