Effect of short-term constant light or constant darkness on the nyctohemeral rhythm of type-II iodothyronine 5'-deiodinase activity in rat anterior pituitary and pineal.
Type-II iodothyronine 5'-deiodinase activity (5'-D) in both anterior pituitary and pineal was significantly elevated at 2400 h, approximately 0.5- and 20-fold higher than the noon value, respectively. The nocturnal rise in both organs was abolished by 6 h additional light. Short-term constant darkness did not alter 5'-D rhythmicity in either organ. These data suggest that environmental lighting plays an important role in the control of the 5'-D nyctohemeral rhythm in both anterior pituitary and pineal.
Murakami
M
M
Department of Medicine, Oregon Health Sciences University, Portland 97201.
Greer
M A
MA
Greer
S E
SE
Hjulstad
S
S
Tanaka
K
K
D000818:Animals; D002940:Circadian Rhythm / Q000528:radiation effects*; D003624:Darkness; D007453:Iodide Peroxidase / Q000378:metabolism*; D008027:Light; D008297:Male; D010870:Pineal Gland / Q000201:enzymology*; D010903:Pituitary Gland, Anterior / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains
D007453:Iodide Peroxidase