Adrenocorticotropin analogs and glucocorticoids in the hypophysectomized rat. I. Effects on liver polyribosomes and rough endoplasmic reticulum.
Hypophysectomy decreased polyribosome aggregation and activity in rat liver. Polyribosome aggregation was measured by sucrose density gradient analysis and polyribosome activity was determined by the incorporation of labeled amino acids into protein in a cell-free system using pH 5 enzymes from sham-operated rats. Hypophysectomy also totally disorganized the rough endoplasmic reticulum of hepatocytes, as shown by electron micrographs. The sc administration of the ACTH fragments, Hoe 433 (corticotropic) and Org 2766 (noncorticotropic), and of glucocorticoids (dexamethasone or corticosterone) to hypophysectomized rats restored these parameters to the levels recorded in sham-operated rats in a dose-dependent fashion 5 h after injection; the effects were maintained until at least 24 h. The sc administration of the noncorticotropic but metabolically less stable fragment, ACTH-(1-10), had only a partial effect. The potency of a noncorticotropic ACTH fragment (Org 2766) in hypophysectomized rats suggests that ACTH may act on liver protein synthesis without the intervention of glucocorticoids or pituitary hormones.
D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D003345:Corticosterone / Q000494:pharmacology*; D003609:Dactinomycin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D007016:Hypophysectomy; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D051381:Rats
D003609:Dactinomycin; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone