title: Effect of goitrogen administration on the circadian rhythm of serum thyroid stimulating hormone in the rat.
abstract: Adult male rats were fed a goitrogen, aminotriazole, for 74 days at a dose known to suppress thyroid function completely. At the end of this period, these animals along with matched controls were killed in groups of seven at 3 hourly intervals throughout a 24 hour period, and serum TSH, T3, T4 and albumin assayed. No significant circadian rhythms of T3, T4 or albumin were found in either, but a highly significant rhythm of TSH was demonstrated both in controls and goitrogen treated groups, with a diminished relative amplitude in the latter. The results indicate that a significant diurnal rhythm of serum TSH persists in the rat despite long-term blockade of thyroid hormone synthesis and that the existence of this rhythm is therefore independent of the presence of circulating T3 or T4.
mesh_terms: D000640:Amitrole / Q000494:pharmacology*; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012709:Serum Albumin / Q000032:analysis; D013963:Thyroid Hormones / Q000096:biosynthesis; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014230:Triazoles / Q000494:pharmacology*; D014284:Triiodothyronine / Q000097:blood
chemical_list: D012709:Serum Albumin; D013963:Thyroid Hormones; D014230:Triazoles; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine; D000640:Amitrole