Changes in Thyroid Hormone Concentrations and Total Contents through Ontogeny in Three Anuran Species: Evidence for Daily Cycles

• Published in: General and comparative endocrinology 1997-08, Vol.107 (2), p.240-250
• Main Authors: Gancedo, B., Alonso-Gómez, A.L., de Pedro, N., Delgado, M.J., Alonso-Bedate, M.
• Format: Article
• Language: English
• Subjects: Animals; Bufonidae - embryology; Bufonidae - growth & development; Bufonidae - metabolism; Circadian Rhythm; Larva - metabolism; Metamorphosis, Biological; Ranidae - embryology; Ranidae - growth & development; Ranidae - metabolism; Thyroid Hormones - metabolism; Thyroxine - metabolism; Triiodothyronine - metabolism; Xenopus laevis - embryology; Xenopus laevis - growth & development; Xenopus laevis - metabolism
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1006/gcen.1997.6922

Three anuran species (Rana perezi, Xenopus laevis,andBufo calamita) of different phylogenetic origins and ecological habitats have been studied during ontogeny with respect to day/night changes in whole-body concentrations and total content of extrathyroidal thyroxine (T4) and triiodothyronine (T3). There were no significant day/night changes in thyroid hormones (TH) during embryonic stages. Daily cycles in TH with higher nocturnal values appeared during premetamorphosis inR. pereziandX. laevis.Cyclicity disappears for T3, while it is reversed for T4, in prometamorphicR. pereziandX. laevis.In contrast, there were significantly higher T3(0.74±0.13 ng/g) and T4(2.08±0.54 ng/g) levels at night in prometamorphicB. calamita.Significant daily changes in T3and T4with higher nocturnal values (T3, 788.29±118.38 pg/g; T4, 1.95±0.4 ng/g) were again seen inX. laevisat the end of climax, while inB. calamitalow TH values appeared at early scotophase and there were no significant changes inR. pereziat this time. Similar daily profiles were observed for TH whole-body concentrations and total contents.