Xiao Q, Nikodem V M
Mechanism of Gene Regulation Section, Genetics and Biochemistry Branch, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, 10 Center Dr. MSC 1766, Bethesda, MD 20892-1766, USA.
Front Biosci. 1998 Sep 15;3:A52-7. doi: 10.2741/a252.
The mechanism underlying transient reduction of cell number in the developing cerebellum have been studied for several decades. In this study we analyzed cell death by apoptosis in the developing cerebellum of euthyroid and hypothyroid rats. Results showed that in both groups the apoptotic activity is limited to the internal granular layer from postnatal (p) day 2 to day 12 in euthyroid animals, with the peak at 8 days. No apoptotic cells were detected in the cerebellum of 22 days old euthyroid rats. The level of apoptosis in the cerebellum of hypothyroid rats also reached a peak at 8 days but was four times higher than in control animals. Apoptosis in hypothyroid animals was also observed at p22 and corresponds to the value found in the time of the apoptotic peak in euthyroid cerebellum. At the age of 42 days, no apoptotic cells were found in the cerebellum of either group. Furthermore, it appears that the hormone also plays a role in the disappearance of the external germinal layer, since its presence is still apparent in 42 day old hypothyroid cerebellum. Hence, our results suggest that the deficiency of thyroid hormone (TH) not only increases, but also extends apoptosis during rat cerebellum development and affects the disappearance of the external germinal layer.
几十年来，人们一直在研究发育中小脑细胞数量短暂减少的潜在机制。在本研究中，我们分析了甲状腺功能正常和甲状腺功能减退大鼠发育中小脑的凋亡性细胞死亡。结果显示，在两组中，甲状腺功能正常动物在出生后（p）第2天至第12天，凋亡活性仅限于内颗粒层，在第8天达到峰值。在22日龄甲状腺功能正常的大鼠小脑中未检测到凋亡细胞。甲状腺功能减退大鼠小脑中的凋亡水平在第8天也达到峰值，但比对照动物高四倍。在p22时也观察到甲状腺功能减退动物的凋亡，且与甲状腺功能正常的小脑凋亡峰值时的值相当。在42日龄时，两组小脑中均未发现凋亡细胞。此外，激素似乎在外部生发层的消失中也起作用，因为在42日龄甲状腺功能减退的小脑中其仍然明显存在。因此，我们的结果表明，甲状腺激素（TH）缺乏不仅会增加大鼠小脑发育过程中的凋亡，还会延长凋亡时间，并影响外部生发层的消失。
