MacKenzie D S
Poult Sci. 1981 Sep;60(9):2136-43. doi: 10.3382/ps.0602136.
Thyroxine (T4) level in the blood of newly hatched cockerels were measured at different times after the injection of bovine thyrotropin. A linear response to increasing doses of mammalian thyrotropin was seen when a two-injection protocol was used with a fifteen-hour interval between injections. Blood T4 levels peaked 5 hr after the second injection and declined thereafter. This response was shown to be highly specific for thyrotropin from both mammalian and avian sources; gonadotropins, prolactin, and growth hormone had negligible activity, although the last two hormones were able to synergise with thyrotropin under certain circumstances to augment the response. Experiments conducted at different times of day indicated that diurnal fluctuations in the response of the thyroid to exogenous thyrotropins may exist. As a result, animals were injected and bled at the same time of day in all subsequent experiments. Under these circumstances, in vivo thyroxine release in cockerels appears to be precise, simple, and sensitive bioassay for thyrotropin. This bioassay can be used to demonstrate that thyrotropin purified from ostrich pituitaries is distinct from gonadotropin and active in an avian species.
在给新孵出的公鸡注射牛促甲状腺激素后的不同时间，测量其血液中的甲状腺素（T4）水平。当采用两次注射方案且两次注射间隔15小时时，观察到对增加剂量的哺乳动物促甲状腺激素呈线性反应。血液T4水平在第二次注射后5小时达到峰值，随后下降。结果表明，这种反应对来自哺乳动物和鸟类来源的促甲状腺激素具有高度特异性；促性腺激素、催乳素和生长激素的活性可忽略不计，尽管后两种激素在某些情况下能够与促甲状腺激素协同作用以增强反应。在一天中的不同时间进行的实验表明，甲状腺对外源性促甲状腺激素的反应可能存在昼夜波动。因此，在所有后续实验中，动物均在同一天的同一时间注射和采血。在这些情况下，公鸡体内甲状腺素的释放似乎是一种精确、简单且灵敏的促甲状腺激素生物测定法。这种生物测定法可用于证明从鸵鸟垂体中纯化的促甲状腺激素与促性腺激素不同，且在鸟类物种中具有活性。
