Sivilotti L, Nistri A
Department of Pharmacology, St Bartholomew's Hospital Medical College, University of London, U.K.
Neuropharmacology. 1989 Oct;28(10):1107-12. doi: 10.1016/0028-3908(89)90124-x.
Excitatory synaptic transmission, induced by electrical stimulation of optic nerve fibres on relay neurones, was recorded from in vitro preparations of the optic tectum of the frog. Bath-applied glutamate (the putative excitatory transmitter of the optic nerve) produced transient enhancement of tectal field potentials, followed by a depression, presumably caused by sustained neuronal depolarization. Pentobarbitone potently antagonized the depressant effect of glutamate, producing an approximate 50% reduction in the response of the tectum to glutamate at 25 microM. Midazolam also decreased the effect of glutamate with an IC50 value of 5 nM. Since, in the optic tectum of the frog, neither pentobarbitone nor midazolam enhance responses to bath-applied GABA, it is suggested that this area of the brain is a useful preparation in which to investigate the interaction of barbiturates and benzodiazepines with glutamate receptor mechanisms, without concurrent interactions with GABAergic processes.
通过对蛙视顶盖体外制备物中中继神经元上的视神经纤维进行电刺激，记录兴奋性突触传递。浴加谷氨酸（视神经假定的兴奋性递质）使视顶盖场电位产生短暂增强，随后出现抑制，推测这是由持续性神经元去极化引起的。戊巴比妥能有效拮抗谷氨酸的抑制作用，在25微摩尔时使视顶盖对谷氨酸的反应降低约50%。咪达唑仑也能降低谷氨酸的作用，其半数抑制浓度（IC50）值为5纳摩尔。由于在蛙的视顶盖中，戊巴比妥和咪达唑仑均未增强对浴加γ-氨基丁酸（GABA）的反应，因此提示大脑的这一区域是一个有用的制备物，可用于研究巴比妥类药物和苯二氮䓬类药物与谷氨酸受体机制的相互作用，而不会同时与GABA能过程相互作用。
