There is a nyctohemeral rhythm of type II iodothyronine 5'-deiodinase activity in rat anterior pituitary.
We found a nyctohemeral rhythm of type II iodothyronine 5'-deiodinase (5'-D-II) with a zenith at midnight in rat anterior pituitary, but not in brown adipose tissue. There was no nyctohemeral rhythm of 5'-D-I in anterior pituitary, liver, or kidney. Hypothyroidism abolished the nyctohemeral rhythmicity in anterior pituitary 5'-D-II. The rhythmicity of anterior pituitary 5'-D-II may play a role in setting the nyctohemeral rhythm of TSH secretion by regulating the degree of negative feedback by locally generated T3 in the thyrotroph.
Murakami
M
M
Department of Medicine, Oregon Health Sciences University, Portland 97201.
Tanaka
K
K
Greer
M A
MA
D002001:Adipose Tissue, Brown / Q000201:enzymology; D000818:Animals; D002940:Circadian Rhythm; D003624:Darkness; D007037:Hypothyroidism / Q000201:enzymology; D007453:Iodide Peroxidase / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D010903:Pituitary Gland, Anterior / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013961:Thyroid Gland / Q000502:physiology; D013963:Thyroid Hormones / Q000097:blood
D013963:Thyroid Hormones; D007453:Iodide Peroxidase