Involvement of proteolytic enzymes in the lipotropic effect of the pituitary polypeptide hormones.
The influence of proteinase inhibitors on the lipolytic effect of the pituitary polypeptide hormones and epinephrine in an isolated adipose tissue of rabbits and rats has been studied. Neither of proteinase inhibitors changed the basal rate of lipolysis. Trasylol, a serine proteinase inhibitor, suppressed completely growth hormone (GH) effect and partially reduced the effect of adrenocorticotropin (ACTH) and beta-lipotropin (beta-LPH) but did not change the effect of epinephrine. Bacitracin proved ineffective with regard to the effect of polypeptide hormones. Pepstatin, an acid proteinase inhibitor, partially blocked the stimulation of lipolysis by ACTH without affecting the effect of GH and beta-LPH. The influence of proteinase inhibitors on the ACTH effect in rat adipose tissue was similar to that found in rabbit tissue. The Trasylol-induced inhibition of the hormone-stimulated lipolysis decreased to a considerable extent after GH or ACTH incubation with rabbit plasma or partial GH digestion with pepsin. This decrease was not observed when plasma serine proteinases were blocked during GH incubation with plasma. The results demonstrate an involvement of some proteolytic enzymes in the realization of the polypeptide hormone lipolytic effect and permit to suppose the requirement of preliminary activation of the hormones by means of proteolytic modification.
D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D007611:Aprotinin / Q000494:pharmacology; D001414:Bacitracin / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D010434:Pepsin A / Q000494:pharmacology; D010436:Pepstatins / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism / Q000494:pharmacology*; D010949:Plasma / Q000502:physiology; D011480:Protease Inhibitors / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains
D010436:Pepstatins; D010907:Pituitary Hormones; D011480:Protease Inhibitors; C014195:Streptomyces pepsin inhibitor; D001414:Bacitracin; D000324:Adrenocorticotropic Hormone; D007611:Aprotinin; D010447:Peptide Hydrolases; D010434:Pepsin A; C031375:pepstatin