The effects of ACTH on adrenal steroidogenesis and blood corticosteroid levels in the echidna (Tachyglossus aculeatus).
1. The effects of short-term (S.T., 30 min) and long-term (L.T., 4 days) administration of ACTH on peripheral blood corticosteroid levels and on in vitro steroidogenesis were investigated. 2. Control levels of cortisol, corticosterone and aldosterone were 58 +/- 12, 130 +/- 26 and 10 +/- 6 (SEM) ng/100 ml respectively. 3. Corticosterone was 70% higher after S.T. and 150% higher after L.T., when cortisol was 800% higher. 4. Adrenal homogenates from control echidnas converted [14C]progesterone predominantly to 11-deoxycorticosterone (45%) and 11-deoxycortisol (12%). 5. After L.T. the principal product was corticosterone (25%), but S.T. had no effect. 6. In control echidnas the Km and V for 11 beta-hydroxylation of 11-deoxycorticosterone were 20 microM and 2.8 rho mol/min/mg respectively. After L.T. V increased to 10 rho mol/min/mg.
D000305:Adrenal Cortex Hormones / Q000097:blood*; D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000493:pharmacokinetics / Q000494:pharmacology*; D000450:Aldosterone / Q000097:blood; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000097:blood; D003350:Cortodoxone / Q000097:blood; D003900:Desoxycorticosterone / Q000097:blood; D006854:Hydrocortisone / Q000097:blood; D009007:Monotremata / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D013256:Steroids / Q000096:biosynthesis*; D004442:Tachyglossidae / Q000378:metabolism*
D000305:Adrenal Cortex Hormones; D013256:Steroids; D003900:Desoxycorticosterone; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone; D003350:Cortodoxone; D006854:Hydrocortisone