Ruiz-Marcos A, Sanchez-Toscano F, Obregon M J, Escobar del Rey F, Morreale de Escobar G
Brain Res. 1982 May 13;239(2):559-74. doi: 10.1016/0006-8993(82)90530-3.
We have previously shown that changes occur in pyramids of area 17 of the rat visual cortex both after thyroidectomy (T) at 10 and at 40 days of age. To assess the effects of thyroxine treatment, instituted at different ages after T, two series of experiments were performed. A : rats were T at 10 days of age and either left untreated, or injected once daily with 1.5 micrograms thyroxine (T4)/100 g body weight. Treatment was started at 12, 15, 20, 30 or 40 days of age. Groups of untreated and T4-treated T rats and of age-paired intact controls were killed at different ages, ranging from 40 to 80 days. B : rats were T at 40 days of age, a group being treated with the same T4 dose starting 30 days after T. These animals, solvent-treated T rats and intact age-paired controls were killed at 90 days of age. The number and distribution of spines along the shaft of Golgi-stained pyramidal cells of the visual cortex were measured and fitted by a mathematical model developed previously. Body weights, pituitary growth hormone contents, plasma thyrotropic hormone, thyroxine and triiodothyronine levels were measured to assess the degree of hypothyroidism. It was found that treatment with T4 of rats T at 10 days of age prevented the alterations of pyramidal cells, provided treatment was started by 12 days of age and euthyroidism was maintained. In rats T at 40 days of age, treatment with T4 had an ameliorating effect despite a delay in onset of treatment of 30 days after T. Whatever the mechanisms which are involved, the present results stress once more the importance of very early treatment of hypothyroid newborns, if permanent cortical brain damage is to be prevented.
我们之前已经表明，在10日龄和40日龄的大鼠进行甲状腺切除术后，其视皮层17区的锥体发生了变化。为了评估甲状腺切除术后不同年龄开始的甲状腺素治疗的效果，进行了两个系列的实验。A：大鼠在10日龄时进行甲状腺切除，要么不进行治疗，要么每天注射1.5微克甲状腺素（T4）/100克体重。治疗在12、15、20、30或40日龄开始。未治疗和T4治疗的甲状腺切除大鼠组以及年龄匹配的完整对照组在40至80天的不同年龄处死。B：大鼠在40日龄时进行甲状腺切除，一组在甲状腺切除术后30天开始用相同剂量的T4治疗。这些动物、溶剂处理的甲状腺切除大鼠和年龄匹配的完整对照组在90日龄处死。测量视皮层经高尔基染色的锥体细胞轴突上棘的数量和分布，并通过先前开发的数学模型进行拟合。测量体重、垂体生长激素含量、血浆促甲状腺激素、甲状腺素和三碘甲状腺原氨酸水平，以评估甲状腺功能减退的程度。结果发现，10日龄进行甲状腺切除的大鼠用T4治疗可预防锥体细胞的改变，前提是在12日龄前开始治疗并维持甲状腺功能正常。在40日龄进行甲状腺切除的大鼠中，尽管在甲状腺切除术后30天才开始治疗，但T4治疗仍有改善作用。无论涉及何种机制，目前的结果再次强调了如果要预防永久性皮质脑损伤，对甲状腺功能减退的新生儿进行极早期治疗的重要性。
