HETEROGENEOUS RESPONSE OF HYPOPHYSEAL COR TICOTROPH CELLS TO CORTICOTROPIN-RELEASING-FACTOR AND ARGININE-VASOPRESSIN IN 4 SPECIES, RAT, GUINEA-PIG, RABBIT AND SHEEP

The injection of corticotropin-releasing-factor (CRF), arginine-vasopr essin (AVP) and of both peptides simultaneously increased plasma ACTH concentration. This stimulation of corticotrophs changed with age stag es of animals and birth maturity. Differences occured in the parts of the different circulating molecular forms of ACTH after stimulation wi th CRF or AVP. Three different immunoreactive forms against the same s pecific antibody anti-ACTH were isolated by column chromatography: a ' 'big'' form of MW higher than 20 KDa, an ''intermediate'' glycosylated form of MW varying with the studied species (8 KDa in the sheep, 9.5 KDa in the guinea pig and the rabbit and 14.5 KDa in the rat) and the ''little'' forme 1-39 ACTH of MW 4.5 KDa. In the sheep the ''little'' form is predominant and CRF increased this whereas AVP increased the ' 'intermediate'' form. In the guineapig and the rabbit,the ''big'' form was the most concentrated and CRF as AVP increased sharply the ''inte rmediate'' form excepted the non-responsive young rabbit. In the rat t he ''intermediate'' form was predominant; CRF increased it in young an d adult animals whereas AVP increased it only in adults.