Becquet D, Héry M, Deprez P, Faudon M, Fache M P, Giraud P, Héry F
Laboratoire de Neuroendocrinologie Expérimentale, INSERM U. 297, UER Faculté de Médecine-Nord, Marseille, France.
J Neurochem. 1993 Nov;61(5):1692-7. doi: 10.1111/j.1471-4159.1993.tb09805.x.
Glutamic acid and glycine were quantified in cells and medium of cultured rostral rhombencephalic neurons derived from fetal rats. In the presence of 1 mM Mg2+, NMDA (50 microM) significantly stimulated (by 69%) release of newly synthesized 5-[3H]hydroxytryptamine ([3H]5-HT). D-2-Amino-5-phosphonopentanoate (AP-5; 50 microM) blocked the stimulatory effect of NMDA. AP-5 by itself inhibited [3H]5-HT release (by 25%), suggesting a tonic control of 5-HT by glutamate. In the absence of Mg2+, basal [3H]5-HT release was 60% higher as compared with release with Mg2+. AP-5 blocked the increased [3H]5-HT release observed without Mg2+, suggesting that this effect was due to the stimulation of NMDA receptors by endogenous glutamate. Glycine (100 microM) inhibited [3H]5-HT release in the absence of Mg2+. Strychnine (50 microM) blocked the inhibitory effect of glycine, indicating an action through strychnine-sensitive inhibitory glycine receptors. The [3H]5-HT release stimulated by NMDA was unaffected by glycine. In contrast, when tested in the presence of strychnine, glycine increased NMDA-evoked [3H]5-HT release (by 22%), and this effect was prevented by a selective antagonist of the NMDA-associated glycine receptor, 7-chlorokynurenate (100 microM). 7-Chlorokynurenate by itself induced a drastic decrease in [3H]5-HT release, indicating that under basal conditions these sites were stimulated by endogenous glycine. These results indicate that NMDA stimulated [3H]5-HT release in both the presence or absence of Mg2+. Use of selective antagonists allowed differentiation of a strychnine-sensitive glycine response (inhibition of [3H]5-HT release) from a 7-chlorokynurenate-sensitive response (potentiation of NMDA-evoked [3H]5-HT release).
对源自胎鼠的培养延髓后脑神经元的细胞和培养基中的谷氨酸和甘氨酸进行了定量分析。在存在1 mM Mg2+的情况下，NMDA（50 μM）显著刺激（增加69%）新合成的5-[3H]羟色胺（[3H]5-HT）的释放。D-2-氨基-5-膦酸戊酸（AP-5；50 μM）阻断了NMDA的刺激作用。AP-5自身抑制[3H]5-HT的释放（降低25%），提示谷氨酸对5-HT存在紧张性调控。在不存在Mg2+的情况下，基础[3H]5-HT释放量比存在Mg2+时高60%。AP-5阻断了在无Mg2+时观察到的[3H]5-HT释放增加，提示这种效应是由于内源性谷氨酸对NMDA受体的刺激所致。甘氨酸（100 μM）在无Mg2+时抑制[3H]5-HT的释放。士的宁（50 μM）阻断了甘氨酸的抑制作用，表明其通过对士的宁敏感的抑制性甘氨酸受体起作用。NMDA刺激的[3H]5-HT释放不受甘氨酸影响。相反，当在士的宁存在下进行测试时，甘氨酸增加了NMDA诱发的[3H]5-HT释放（增加22%），并且这种效应被NMDA相关甘氨酸受体的选择性拮抗剂7-氯犬尿氨酸（100 μM）所阻断。7-氯犬尿氨酸自身导致[3H]5-HT释放急剧减少，表明在基础条件下这些位点受到内源性甘氨酸的刺激。这些结果表明，无论有无Mg2+，NMDA均刺激[3H]5-HT的释放。使用选择性拮抗剂能够区分对士的宁敏感的甘氨酸反应（抑制[3H]5-HT释放）和对7-氯犬尿氨酸敏感的反应（增强NMDA诱发的[3H]5-HT释放）。
