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Oral thyroxine administration mimics photoperiodically induced gonadal growth in Japanese quail
Author(s) -
YASUO Shinobu,
EBIHARA Shizufumi,
YOSHIMURA Takashi
Publication year - 2004
Publication title -
animal science journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.606
H-Index - 38
eISSN - 1740-0929
pISSN - 1344-3941
DOI - 10.1111/j.1740-0929.2004.00205.x
Subject(s) - quail , medicine , endocrinology , triiodothyronine , biology , photoperiodism , development of the gonads , hormone , gonad
Most temperate‐zone animals are seasonal breeders. In a previous study, it was found that light‐induced hormone conversion of thyroxine (T 4 ) prohormone to active 3,5,3′‐triiodothyronine (T 3 ) in the mediobasal hypothalamus regulates photoperiodic response of gonads in Japanese quail. Here the effect of T 4 or T 3 , administered in drinking water, on testicular growth in the Japanese quail kept under short days is shown. Testicular length was significantly increased in birds given T 4 at doses of 4, 8 and 10 mg/L, while any dose of T 3 had little effect on testicular growth. High doses (8 and 10 mg/L) of T 4 and T 3 resulted in high mortality and/or reduction of bodyweight. Among all of the treatment, 4 mg/L of T 4 was the most effective on photoperiodic testicular growth, which caused little reduction in bodyweight. These data provide a new conventional method for promoting gonadal growth under short days.