Biological Activity of Synthetic Corticotrophin with Short Chain Lengths in the Rabbit

抄録

The adrenocorticotrophic effect of a synthetic substituted adrenocorticortophic hormone (ACTH), α^1-18NH₂-D-Ser¹-Lys^{17, 18}-ACTH (CIBA 41, 795-Ba) has been compared with that of α^1-24-ACTH (tetracosactide), α^1-24-ACTH depot (tetracosactide depot) and α^1-18NH₂-Gly¹-ACTH (giractide) in the rabbit. Plasma corticosteroid levels after saline injection were higher in the afternoon than in the morning. The highest value was observed at 3 p.m. 41, 795-Ba, either given intravenously or intramuscularly, was shown to be the most potent peptide followed by tetracosactide depot and was 15 times more potent than tetracosactide and giractide in steroidogenic activity in the rabbit The intravenous administration of 41, 795-Ba caused more sustained stimulation of the adrenal cortex than the intramuscular injection. These results reveal the diurnal variation pattern of the pituitary-adrenal axis of the rabbit similar to that of the rat and also confirm the finding that α^1-18NH₂-D-Ser¹-Lys^{17, 18}-ACTH is a potent adrenocorticotrophic peptide without the addition of any agent to delay its absorption in the rabbit.