Licht P, Denver R J
Department of Zoology, University of California, Berkeley 94720.
Gen Comp Endocrinol. 1988 Jun;70(3):355-62. doi: 10.1016/0016-6480(88)90109-8.
The ability of thyrotropin-releasing hormone (TRH) to stimulate thyrotropin (TSH) from pituitaries of adult male lizards, Anolis carolinensis, was tested in vivo and in vitro. TSH output by pituitaries in vitro was determined by bioassay of the incubation medium using in vitro T4 output by thyroids from the same lizards. Pituitaries incubated without TRH had no detectable TSH secretion during two consecutive (2 or 3 hr) periods of incubation. Incubation in 10 or 100 ng/ml TRH for 2 or 3 hr significantly augmented release of TSH bioactivity in a dose-dependent manner. Pituitaries taken from goitrogen (100 micrograms methimazole/day for 10 days)-treated lizards had elevated basal TSH secretion but did not respond to TRH. TRH injection in vivo (5 micrograms/hr for 10 hr) appeared to stimulate acute release of MSH activity as judged by darkening of skin color after each injection, and plasma T4 was significantly elevated at the end of treatment. These results provide additional evidence that the reptilian thyrotrope has functional TRH receptors and the TSH-stimulating activity of the tripeptide along with its effects on other pituitary cells was present at an early stage of reptilian evolution.
在体内和体外对促甲状腺激素释放激素（TRH）刺激成年雄性绿安乐蜥垂体分泌促甲状腺激素（TSH）的能力进行了测试。体外垂体的TSH分泌量通过对孵育培养基进行生物测定来确定，该生物测定使用来自相同蜥蜴甲状腺的体外T4分泌量。在连续两个（2或3小时）孵育期内，未添加TRH孵育的垂体未检测到TSH分泌。在10或100 ng/ml的TRH中孵育2或3小时，TSH生物活性的释放以剂量依赖的方式显著增加。取自用致甲状腺肿物质（100微克甲巯咪唑/天，持续10天）处理的蜥蜴的垂体，其基础TSH分泌升高，但对TRH无反应。体内注射TRH（5微克/小时，持续10小时）似乎刺激了MSH活性的急性释放，每次注射后皮肤颜色变深可判断这一点，并且在治疗结束时血浆T4显著升高。这些结果提供了额外的证据，表明爬行动物的促甲状腺细胞具有功能性TRH受体，并且这种三肽的TSH刺激活性及其对其他垂体细胞的作用在爬行动物进化的早期阶段就已存在。
