Gutiérrez R, Heinemann U
Institut für Physiologie der Charité, Humboldt Universität zu Berlin, Tucholsky-Str. 2, 10117, Berlin, Germany.
Brain Res. 1999 Jan 9;815(2):304-16. doi: 10.1016/s0006-8993(98)01101-9.
Due to loss of afferent innervation, synaptic reorganization occurs in organotypic hippocampal slice cultures. With extra- and intracellular recordings, we confirm that the excitatory loop from the dentate gyrus (DG) to CA3 and further to CA1 is preserved. However, hilar stimulation evoked antidromic population spikes in the DG which were followed by a population postsynaptic potential (PPSP); intracellularly, an antidromic spike with a broad shoulder or EPSP/IPSP sequences were induced. Synaptic responses were blocked by glutamate receptor antagonists. Stimulation of CA1 induced a PPSP in DG. Dextranamine stained pyramidal cells of CA1 were shown to project to DG. After removal of area CA3, DG's and mossy fibers' (MF) stimulation still elicited PPSPs and EPSP/IPSP sequences in area CA1 which disappeared when a cut was made through the hippocampal fissure. During bicuculline perfusion, hilar stimulation caused EPSPs in granule cells and spontaneous and evoked repetitive firing appeared even after its isolation from areas CA3 and CA1. Collateral excitatory synaptic coupling between granule cells was confirmed by paired recordings. Besides the preservation of the trisynaptic pathway in this preparation, new functional synaptic contacts appear, presumably due to MF collateral sprouting and formation of pathways between areas CA1 and DG.
由于传入神经支配的丧失，在器官型海马切片培养物中会发生突触重组。通过细胞外和细胞内记录，我们证实从齿状回（DG）到CA3再到CA1的兴奋性环路得以保留。然而，海马门刺激在DG中诱发了逆向群体峰电位，随后是群体突触后电位（PPSP）；在细胞内，诱发了具有宽峰肩的逆向峰电位或EPSP/IPSP序列。突触反应被谷氨酸受体拮抗剂阻断。刺激CA1在DG中诱发了PPSP。经葡聚糖胺染色的CA1锥体细胞显示投射到DG。去除CA3区域后，刺激DG和苔藓纤维（MF）仍能在CA1区域诱发PPSP和EPSP/IPSP序列，而当通过海马裂进行切割时这些序列消失。在荷包牡丹碱灌注期间，海马门刺激在颗粒细胞中引起EPSP，并且即使在其与CA3和CA1区域分离后仍出现自发和诱发的重复放电。通过配对记录证实了颗粒细胞之间的侧支兴奋性突触耦合。除了在该制备物中保留三突触通路外，可能由于MF侧支发芽以及CA1和DG区域之间通路的形成，出现了新的功能性突触联系。
