Plasma Levels of Androgens in Growing Frogs of Rana nigromaculata : Endocrinology

概要

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Using young, subadult and adult Rana nigromaculata of both sexes, plasma testosterone and dihydrotestosterone (DHT) levels were determined by radioimmunoassay. In young male frogs, the testosterone concentration was almost constant at ca. 100pg/ml from just after metamorphosis to July of the next year, while the DHT concentration showed a gradual upward tendency and reached a level twice that of newly metamorphosed frogs by May of the next year. In first-year female frogs, the concentrations of testosterone and DHT were ca. 100pg/ml, and had doubled by June of the next year. In second-year male frogs, testosterone and DHT concentrations increased remarkably in autumn, especially in DHT, and reached 8.7ng/ml. In second-year females, testosterone also increased from July on, and reached 1.1ng/ml in the breeding season (the first half of May) of the following year, though the DHT level remained low. Androgen concentrations in adult males were remarkably low just after hibernation compared with those in the preceding autumn (especially in DHT), decreased further until June, and increased again from July until October as the same manner in second-year males. Testosterone concentrations in adult females showed similar changes, though always slightly lower than those of the male frogs of the same age.
社団法人日本動物学会の論文
1988-10-15