van Huizen F, Romijn H J, Habets A M, van den Hooff P
Exp Neurol. 1987 Aug;97(2):280-8. doi: 10.1016/0014-4886(87)90089-6.
Our aim was to determine if chronic blockade of GABAergic inhibitory synaptic activity, monitored electrophysiologically at the neuronal level, would affect synapse formation and ultrastructure in dissociated fetal rat cerebral cortex cultures. This was achieved by adding picrotoxin to the serum-free growth medium in a dose that induced continuous epileptiform discharges throughout the culture period. Light and electron microscopic analysis suggested an accelerated synaptic network formation in the experimental cultures during the first 2 weeks in vitro. The elimination of excess synapses (mainly on spines), which normally takes place during the fourth week in vitro, occurred 1 week earlier in the presence of picrotoxin. Finally, the experimental cultures showed smaller spine synapses throughout the entire culture period. Because these effects were opposite those induced by chronic tetrodotoxin-blockade of spontaneous bioelectric activity in a previous study, the underlying causal factor could be the respective intensification and suppression of neuronal activity in the two experiments. An appropriate balance between excitatory and inhibitory synaptic drive seems therefore to be important for normal maturation of neocortical circuitry.
我们的目的是确定，在神经元水平通过电生理学监测到的GABA能抑制性突触活动的慢性阻断，是否会影响离体培养的胎鼠大脑皮层中突触的形成和超微结构。这是通过向无血清生长培养基中添加苦味毒来实现的，添加剂量要能在整个培养期诱导持续的癫痫样放电。光学显微镜和电子显微镜分析表明，在体外培养的前两周，实验培养物中的突触网络形成加速。通常在体外培养第四周发生的多余突触（主要在棘突上）的消除，在有苦味毒存在的情况下提前一周发生。最后，在整个培养期，实验培养物中的棘突突触都较小。由于这些效应与之前一项研究中慢性河豚毒素阻断自发生物电活动所诱导的效应相反，所以潜在的因果因素可能是这两个实验中神经元活动分别增强和受到抑制。因此，兴奋性和抑制性突触驱动之间的适当平衡似乎对新皮层回路的正常成熟很重要。
