Molecular mechanism of the long-lasting change in the excitability of fetal brain neurons following dam's brain stimulation

本文用在体全细胞记录技术研究了胎鼠下丘脑对上级丘（SC）神经元电生理特性的影响。结果表明：（1）SC神经元静息膜电位为46 ~ 60 mV;（2）细胞内注入去极化电流引起的动作电位幅值较小，为31 ~ 48 mV;而在半最大峰电位振幅下测量的动作电位持续时间为8至25毫秒。3）去极化电流脉冲常引起胎儿SC神经元的缓慢去极化，这在以前的实验中已报道发生在未成熟的脑神经元中。4）电刺激母鼠的下丘脑后，胎儿SC神经元的动作电位幅度增加约15%，5）刺激母鼠下丘脑后，去极化电流脉冲引起的缓慢去极化现象减少。6）这些结果表明母鼠下丘脑的激活通过胎盘影响胎脑神经元膜特性的发育。

The influence of the dam's hypothalamus on the electrophysiological properties of neurons of the superior colliculus (SC) was studied in the fetal rats using the technique of in vivo whole cell recordings, while the fetus was still connected to the dam by the umibilical cord. The folowing results were obtained.1) The resting membrane potential of SC neurons ranged from 46 to 60 mV.2) The amplitude of action potential induced by intracellular injection of a small depolarizing current pulse was small, ranging from 31 to 48 mV, while the duration of action potential measured at half-maximal spike amplitude was 8 to 25 msec.3) Depolarizing current pulse often evoked a slow depolarization in the fetal SC neurons, which has been reported in previous experiments to occur in premature brain neurons.4) The amplitude of action potential of the fetal SC neurons was increased by approximately 15% following electrical stimulation of the dam's hypothalamus, while the duration of action potential was reduced by approximately 26%.5) The slow depolarization induced by depolarizing current pulse became less frequent after stimulation of the dam's hypothalamus.6) These results suggest that activation of the dam's hypothalamus influences the development of membrane properties of the fetal brain neurons through the placenta.