Day-night differences in membrane-bound pyroglutamyl-2-naphthylamide-hydrolyzing activity in rat hypothalamus, pituitary, and retina.
Membrane-bound pyroglutamyl-2-naphthylamide-hydrolyzing enzyme activity was analyzed fluorometrically in the anterior hypothalamus, pituitary, and retina of adult male rats to investigate day-night differences. Six groups (n=6 per group) were assessed--three during the light span and three during the dark span--under a standard 12 h-12 h light-dark cycle (light on from 07:00 to 19:00 h) and controlled temperature environment, with food and water available ad libitum. In the hypothalamus, enzyme activity levels were higher for time points of the dark than the light period. In contrast, the pituitary and retina exhibited the highest levels at the time points of the light period. The pituitary and retina also exhibited significant differences between the clock-hour means of the light period. Day-night differences in membrane-bound pyroglutamyl-2-naphthylamide-hydrolyzing activity may reflect differences in its susceptible endogenous substrates.
Domínguez
Germán
G
Dpto. CC de la Salud, Area de Fisiología, Facultad de CC Experimentales, Jaén, Spain.
Ramírez
Manuel
M
Arechaga
Garbiñe
G
D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D002940:Circadian Rhythm; D003624:Darkness; D006868:Hydrolysis; D007031:Hypothalamus / Q000378:metabolism*; D008027:Light; D008297:Male; D009281:Naphthalenes / Q000378:metabolism*; D009490:Neurosecretory Systems / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism
D009281:Naphthalenes; C406183:pyroglutamyl-naphthylamide; D013973:Thyrotropin-Releasing Hormone; D000626:Aminopeptidases; C023166:pyroglutamyl-peptidase II; D011761:Pyrrolidonecarboxylic Acid