Gancedo B, Alonso-Gómez A L, de Pedro N, Delgado M J, Alonso-Bedate M
Departmento de Biología Animal II (Fisiología Animal), Facultad de Ciencias Biológicas, Universidad Complutense, Madrid, Spain.
Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1996 May;114(1):79-87. doi: 10.1016/0742-8413(96)00009-6.
Plasma triiodothyronine (T3) and thyroxine (T4) levels, as well as thyroid free (f) and bound (b) thyroid hormones (TH) content, were determined by radioimmunoassay (RIA) in adult Rana perezi frogs during a 24 h cycle in winter, spring, summer, and autumn. Significant daily changes in plasma T3 levels were present in all the seasons except for winter, being the lowest values observed during the scotophase. In contrast, plasma T4 only showed significant changes in spring, following a similar pattern to the one described for T3. Thyroid fT3 content did present day/night significant changes only in spring showing high contents at early scotophase. Mean fT4 content was higher at the beginning of light phase than during the rest of daily photocycle in spring and autumn, but significant differences appeared only in autumn. Regarding the thyroid bound content of TH, bT3, and bT4 presented significant daily changes in spring and autumn. However, different profiles were observed in these two seasons. High bound contents were found at early photo- and scotophase with lower values at late dark phase in spring, whereas higher contents were detected at this time in autumn. The present results indicate the existence of seasonally changing daily fluctuations in thyroid activity in Rana perezi and it seems that an interaction between photoperiod and temperature plays a role in the regulation of these daily changes.
在冬季、春季、夏季和秋季的24小时周期内，通过放射免疫分析（RIA）测定成年泽陆蛙血浆中三碘甲状腺原氨酸（T3）和甲状腺素（T4）水平，以及甲状腺游离（f）和结合（b）甲状腺激素（TH）含量。除冬季外，所有季节血浆T3水平均存在显著的每日变化，在暗期观察到的是最低值。相比之下，血浆T4仅在春季显示出显著变化，其模式与T3相似。甲状腺游离T3含量仅在春季出现昼夜显著变化，在暗期早期含量较高。春季和秋季光期开始时的平均游离T4含量高于每日光周期的其余时间，但仅在秋季出现显著差异。关于甲状腺结合TH、结合T3和结合T4的含量，春季和秋季呈现显著的每日变化。然而，在这两个季节观察到不同的变化模式。春季在光照期和暗期早期结合含量较高，在暗期后期较低，而秋季此时检测到的含量较高。目前的结果表明泽陆蛙甲状腺活动存在季节性变化的每日波动，并且光周期和温度之间的相互作用似乎在这些每日变化的调节中起作用。
