Presence of ACTH-potentiating factors in rat anterior pituitary glands.
High molecular weight ACTH fractions, obtained through gel filtration of boiled rat anterior pituitary extract, induced a marked increase in corticosterone production from isolated rat adrenal cells in the presence of low concentrations of ACTH-(1-24). This indicates the presence of heat-stable factors augmenting the steroidogenic action of ACTH in the rat anterior pituitary. We also noted that these factors potentiated the activity not only of ACTH-1(1-24) but also of ACTH-(1-8). The ACTH-potentiating factors in rat anterior pituitary extract are possibly present in heterogeneous forms according to their molecular weights (8,000, 10,000 and 15,000), their mobility in ion-exchange chromatography and their content in RIA-ACTH activity. Of these three forms, the former comigrated with biological ACTH activity. The remaining two forms were free of it. Since the effect of potentiating factors on modified ACTH-(1-9), shown to be less susceptible to proteolytic degradation from ACTH-(1-24), was similar to the effect on ACTH-(1-24), it is suggested that potentiation was not due to an inhibition of ACTH proteolysis.
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D003345:Corticosterone / Q000096:biosynthesis; D004357:Drug Synergism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000502:physiology*; D011498:Protein Precursors / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship; D014020:Tissue Extracts / Q000494:pharmacology*
D011498:Protein Precursors; D014020:Tissue Extracts; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone