Vriend J, Thliveris J A
Anat Rec. 1985 Jan;211(1):29-33. doi: 10.1002/ar.1092110106.
Since previous studies have shown that an active pineal gland exerts an inhibitory effect on circulating levels of thyroxin in the Syrian hamster, a study was conducted to determine whether the histology and ultrastructure of the thyroid gland supported the conclusions drawn from the hormone data. The ultrastructure of thyroid glands of blinded male Syrian hamsters was compared to that of intact controls kept under a 14L/10D photoperiod, to that of blinded hamsters also pinealectomized, and to that of blinded hamsters receiving 80 micrograms/ml of melatonin in the drinking water. Serum thyroxin (T4) and serum thyrotropin (TSH) concentrations were determined by radioimmunoassay. After 10 weeks serum thyroxin concentrations were less than 50% of controls and concentrations were significantly reduced. EM examination revealed that blinded hamsters had an increased number of follicular cells with flattened epithelium and nondilated endoplasmic reticulum compared to intact controls. In blinded hamsters that were pinealectomized or treated with melatonin in the drinking water, the ultrastructure of the thyroid was not different from controls and serum thyroxin concentrations were restored to near normal. These ultrastructural data support the conclusion that the pineal gland is required to obtain inhibition of the pituitary-thyroid axis in blinded hamsters and that melatonin has a counter-inhibitory effect when administered via the drinking water.
由于先前的研究表明，活跃的松果体对叙利亚仓鼠循环中的甲状腺素水平具有抑制作用，因此进行了一项研究，以确定甲状腺的组织学和超微结构是否支持从激素数据得出的结论。将失明雄性叙利亚仓鼠的甲状腺超微结构与处于14小时光照/10小时黑暗光周期下的完整对照仓鼠、也接受松果体切除的失明仓鼠以及饮用含80微克/毫升褪黑素的饮用水的失明仓鼠的甲状腺超微结构进行比较。通过放射免疫测定法测定血清甲状腺素（T4）和血清促甲状腺激素（TSH）浓度。10周后，血清甲状腺素浓度低于对照组的50%，且浓度显著降低。电子显微镜检查显示，与完整对照仓鼠相比，失明仓鼠的滤泡细胞数量增加，上皮细胞扁平，内质网未扩张。在接受松果体切除或饮用含褪黑素的饮用水的失明仓鼠中，甲状腺的超微结构与对照组无异，血清甲状腺素浓度恢复到接近正常水平。这些超微结构数据支持以下结论：在失明仓鼠中，需要松果体来抑制垂体-甲状腺轴，并且当通过饮用水给药时，褪黑素具有反抑制作用。
