Tissue-specific regulation of pyroglutamate aminopeptidase II activity by thyroid hormones.
Among the enzymes capable of degrading thyrotropin-releasing hormone (TRH) in vitro, two pyroglutamate aminopeptidases (PGA) are specific for TRH: thyroliberinase, a seric enzyme and PGAII, a membrane-bound peptidase. The effect of thyroid hormone status on the activity of these enzymes was evaluated in serum and various tissues. Only in adenohypophysis, triiodothyronine treatment increased PGAII to 376% of control; hypothyroidism produced the reverse effect (decrease to 23% of control). As previously reported, similar changes were observed for thyroliberinase. TRH degradation at the adenohypophysis level may participate in the negative feedback control of thyroid hormones.
Ponce
G
G
Departmento de Bioquímica, Universidad Nacional Autónoma de México, Cuernavaca.
Charli
J L
JL
Pasten
J A
JA
Aceves
C
C
Joseph-Bravo
P
P
D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D007037:Hypothyroidism / Q000201:enzymology; D008297:Male; D009928:Organ Specificity; D010903:Pituitary Gland, Anterior / Q000201:enzymology*; D011751:Pyroglutamyl-Peptidase I / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013961:Thyroid Gland / Q000502:physiology*; D014284:Triiodothyronine / Q000494:pharmacology*
D014284:Triiodothyronine; D000626:Aminopeptidases; D011751:Pyroglutamyl-Peptidase I