Mattson M P, Lee R E, Adams M E, Guthrie P B, Kater S B
Department of Anatomy and Neurobiology, Colorado State University, Fort Collins 80523.
Neuron. 1988 Nov;1(9):865-76. doi: 10.1016/0896-6273(88)90134-1.
A coculture system consisting of input axons from entorhinal cortex explants and target hippocampal pyramidal neurons was used to demonstrate that glutamate, released spontaneously from afferent axons, can influence both dendritic geometry of target neurons and formation of presumptive synaptic sites. Dendritic outgrowth was reduced in hippocampal neurons growing on entorhinal axons when compared with neurons growing off the axons. Presumptive presynaptic sites were observed in association with hippocampal neuron dendrites and somas. HPLC analysis showed that glutamate was released from the explants in an activity- and Ca2(+)-dependent manner. The general glutamate receptor antagonist D-glutamylglycine significantly increased dendritic outgrowth in pyramidal neurons associated with entorhinal axons and reduced presumptive presynaptic sites. Tetrodotoxin and reduction of extracellular Ca2+ also promoted dendritic outgrowth and reduced the formation of presumptive synaptic sites. The results suggest that the neurotransmitter glutamate may play important roles in the development of hippocampal circuitry.
一种由内嗅皮质外植体的输入轴突和靶海马锥体神经元组成的共培养系统被用于证明，从传入轴突自发释放的谷氨酸能够影响靶神经元的树突形态以及假定突触位点的形成。与生长在轴突外的神经元相比，生长在内嗅轴突上的海马神经元的树突生长减少。在海马神经元的树突和胞体上观察到了假定的突触前位点。高效液相色谱分析表明，谷氨酸以一种活性和Ca2(+)依赖性方式从外植体中释放。一般的谷氨酸受体拮抗剂D-谷氨酰甘氨酸显著增加了与内嗅轴突相关的锥体神经元的树突生长，并减少了假定的突触前位点。河豚毒素和细胞外Ca2+的减少也促进了树突生长并减少了假定突触位点的形成。这些结果表明，神经递质谷氨酸可能在海马回路的发育中发挥重要作用。
