Spontaneous motoneuronal activity mediated by glycine and GABA in the spinal cord of rat fetuses in vitro
Spontaneous motoneuronal activity mediated by glycine and GABA in the spinal cord of rat fetuses in vitro
复制标题
DOI：
10.1113/jphysiol.1996.sp021755
复制
发表时间：
1996-11-15
影响因子：
5.5
通讯作者：
Kudo, N
中科院分区：
文献类型：
--
作者：
Nishimaru, H;Iizuka, M;Kudo, N
1.自发运动神经元活动监测从腰腹根在一个孤立的脊髓制备大鼠胚胎天（E）13.5-18.5.2。自发爆发，同步在左，右腹根定期观察（平均间隔，1.5-2.6分钟），从E14.5至17.5。这种活性在无钙盐水中或应用河豚毒素（1 μ M）时被消除，表明它是突触介导的。谷氨酸受体阻断剂犬尿氨酸（4 mM）未能阻断E14.5-15.5的自发爆发，尽管它在E17.5完全消除了它们。甘氨酸受体拮抗剂士的宁（10 μ M）在E14.5-15.5完全阻断自发爆发。GABA（A）受体拮抗剂荷包牡丹碱可降低自发爆发的幅度.在E15.5，短暂应用甘氨酸（250 μ M至2 mM）诱发兴奋性反应，类似于自发爆发的时间过程和幅度。这种甘氨酸诱导的反应没有观察到钙离子自由的条件下，这表明它们是突触诱发的。这些突触反应没有被犬尿氨酸（4 mM）阻断，但它们被士的宁（10 μ M）消除。它的结论是，甘氨酸和GABA产生最早的自发运动活动的胎儿和功能短暂的兴奋性递质在胚胎脊髓。
1. Spontaneous motoneuronal activity was monitored from the lumbar ventral roots in an isolated spinal cord preparation from rat fetuses at embryonic days (E) 13.5-18.5.2. Spontaneous bursts that were synchronized in both left and right ventral roots were observed periodically (mean interval, 1.5-2.6 min) from E14.5 to 17.5. This activity was abolished in Ca2+-free saline or by application of tetrodotoxin (1 mu M), indicating that it was synaptically mediated.3. The glutamate receptor blocker kynurenate (4 mM) failed to block spontaneous bursts at E14.5-15.5, though it completely abolished them at E17.5. The glycine receptor antagonist strychnine (10 mu M) completely blocked spontaneous bursts at E14.5-15.5. Bicuculline, a GABA(A) receptor antagonist, reduced the amplitude of the spontaneous bursts.4. At E15.5, a brief application of glycine (250 mu M to 2 mM) evoked excitatory responses resembling the spontaneous bursts in both time course and amplitude. Such glycine-induced responses were not observed under Ca2+-free conditions, suggesting that they were synaptically evoked. These synaptic responses were not blocked by kynurenate (4 mM), but they were abolished by strychnine (10 mu M).5. It is concluded that glycine and GABA generate the earliest spontaneous motor activity of the fetus and function transiently as excitatory transmitters in the embryonic spinal cord.