Salt T E, Eaton S A
Department of Visual Science, Institute of Ophthalmology, London, U.K.
Neurochem Int. 1994 May;24(5):451-8. doi: 10.1016/0197-0186(94)90093-0.
The phenylglycines 3-hydroxyphenylglycine, 4-carboxy-3-hydroxy-phenylglycine (4C3HPG), 4-carboxyphenylglycine (4CPG) and alpha-methyl-4-carboxyphenylglycine (MCPG) were evaluated as putative selective antagonists of metabotropic glutamate receptors on single neurones of the ventrobasal thalamus of rats, with a view to using these compounds as tools to elucidate synaptic mechanisms in this brain area. The S-isomers of the latter three compounds were found to reduce excitations evoked by iontophoretically applied 1S,3R-ACPD, but not those evoked by ionotropic excitatory amino receptor agonists. When the antagonists were tested against sensory synaptic responses of ventrobasal neurones, it was found that responses evoked by noxious thermal stimulation of the peripheral receptive field were reduced in parallel with responses to 1S,3R-ACPD. In contrast, responses of neurones evoked by non-noxious (air-jet) stimuli were not reduced by the phenylglycine antagonists and 4C3HPG was found to enhance such responses, possibly by a presynaptic action mediated via mGluR2 receptors. The reductions of nociceptive responses are discussed in the context of antagonism of mGluR1 receptors, which are known to be numerous in the thalamus and located on post-synaptic dendrites. The involvement of such receptors in the nociceptive responses of thalamic neurones may be of considerable functional significance.
对苯甘氨酸类物质3-羟基苯甘氨酸、4-羧基-3-羟基苯甘氨酸（4C3HPG）、4-羧基苯甘氨酸（4CPG）和α-甲基-4-羧基苯甘氨酸（MCPG）进行了评估，将其作为大鼠腹后丘脑单个神经元上代谢型谷氨酸受体的假定选择性拮抗剂，目的是利用这些化合物作为工具来阐明该脑区的突触机制。发现后三种化合物的S-异构体可减少离子导入施加1S,3R-ACPD所诱发的兴奋，但不减少离子型兴奋性氨基酸受体激动剂所诱发的兴奋。当测试这些拮抗剂对腹后神经元感觉突触反应的作用时，发现外周感受野的有害热刺激所诱发的反应与对1S,3R-ACPD的反应平行降低。相反，苯甘氨酸拮抗剂不会降低由无害（喷气）刺激诱发的神经元反应，并且发现4C3HPG可增强此类反应，可能是通过经由mGluR2受体介导的突触前作用。在mGluR1受体拮抗作用的背景下讨论了伤害性反应的降低，已知mGluR1受体在丘脑中数量众多且位于突触后树突上。此类受体参与丘脑神经元的伤害性反应可能具有相当大的功能意义。
