THYROXINE EFFECTS UPON REPRODUCTION, PROLACTIN SECRETION AND PLUMAGE MOLT IN INTACT AND IN THYROIDECTOMIZED EUROPEAN STARLINGS STURNUS-VULGARIS
THYROXINE EFFECTS UPON REPRODUCTION, PROLACTIN SECRETION AND PLUMAGE MOLT IN INTACT AND IN THYROIDECTOMIZED EUROPEAN STARLINGS STURNUS-VULGARIS
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DOI：
10.2307/3676666
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发表时间：
1992-07-01
期刊：
影响因子：
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通讯作者：
NICHOLLS, TJ
中科院分区：
文献类型：
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作者：
GOLDSMITH, AR;NICHOLLS, TJ
Thyroidectomised male Starlings were injected with thyroxine (50 mug per bird) or with control solution and maintained under long (18L:6D) or short (8L:16D) day-lengths. Thyroxine stimulated normal long day responses (an increase in plasma follicle-stimulating hormone, FSH, followed by a decrease in FSH, gonadal regression, reduction in hypothalamic content of luteinizing hormone-releasing hormone, LHRH, and an increase in plasma prolactin and in plumage moult) under 18L:6D. Thyroxine replacement thus restored the photorefractory condition which is abolished by thyroidectomy. None of these responses was seen in controls nor in birds injected under 8L:16D. A high dose of thyroxine administered in the drinking water (50 mg l-1 for 54 d) caused rapid testicular growth followed by regression in intact male Starlings maintained under 11L:13D (and a rise in plasma prolactin) whilst control birds showed gradual gonadal maturation during the same period (and prolactin levels remained low). The thyroxine-treated birds remained reproductively regressed after withdrawal of exogenous thyroxine and exposure to 18L:6D, confirming the establishment of a photorefractory condition.
