Escrivá F, Pascual-Leone A M
Endocrinology. 1981 Jan;108(1):336-40. doi: 10.1210/endo-108-1-336.
The neo-T4 syndrome was induced by sc administration of high doses (30 microgram) of L-T4 (T4) during 5 consecutive days in the early postnatal period. Rats were injected starting on the 3rd or 6th day of life. Blood glucose and insulin levels as well as liver glycogen levels were determined between the 5th and 20th days of life. This covers the critical period for brain development (the 7th to 12th day) during which most myelination takes place. Blood glucose and insulin and liver glycogen started to decrease after the second injection of T4 and remained quite low until 2 days after the last injection. Glucose tolerance testing was performed on 8- and 12-day-old neo-T4 rats; treatment was started at 3 days of age. After 70 min of fasting, 200 mg glucose/100 g BW were injected ip. Low plasma insulin levels were found after a glucose load. Plasma ketone bodies were higher in neo-T4 rats than in controls after 4 or 5 days of treatment. The rats appeared to be in a severe catabolic state and were using up their reserves. These alterations in carbohydrate metabolism in suckling rats should be considered when interpreting the brain damage produced by large doses of T4 during the early neonatal period.
新生期T4综合征是通过在出生后早期连续5天皮下注射高剂量（30微克）的L-T4（T4）诱导产生的。大鼠从出生后第3天或第6天开始注射。在出生后第5天至第20天期间测定血糖、胰岛素水平以及肝糖原水平。这涵盖了大脑发育的关键时期（第7天至第12天），在此期间大部分髓鞘形成过程发生。在第二次注射T4后，血糖、胰岛素和肝糖原开始下降，并一直保持在相当低的水平，直到最后一次注射后2天。对8日龄和12日龄的新生期T4大鼠进行了葡萄糖耐量试验；治疗从3日龄开始。禁食70分钟后，腹腔注射200毫克葡萄糖/100克体重。葡萄糖负荷后发现血浆胰岛素水平较低。治疗4或5天后，新生期T4大鼠的血浆酮体水平高于对照组。这些大鼠似乎处于严重的分解代谢状态，正在消耗自身储备。在解释新生儿早期大剂量T4所造成的脑损伤时，应考虑乳鼠碳水化合物代谢的这些改变。
