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 |
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Authors: | M Murakami M A Greer S E Greer S Hjulstad K Tanaka |
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Affiliation: | Department of Medicine, Oregon Health Sciences University, Portland 97201. |
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Abstract: | 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. |
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