ATP Induces NO Production in Hippocampal Neurons by P2X₇ Receptor Activation Independent of Glutamate Signaling

To assess the putative role of adenosine triphosphate (ATP) upon nitric oxide (NO) production in the hippocampus, we used as a model both rat hippocampal slices and isolated hippocampal neurons in culture, lacking glial cells. In hippocampal slices, additions of exogenous ATP or 2′(3′)-O-(4-Benzoylbenzoyl) ATP (Bz-ATP) elicited concentration-dependent NO production, which increased linearly within the first 15 min and plateaued thereafter; agonist EC50 values were 50 and 15 µM, respectively. The NO increase evoked by ATP was antagonized in a concentration-dependent manner by Coomassie brilliant blue G (BBG) or by Nω-propyl-L-arginine, suggesting the involvement of P2X7Rs and neuronal NOS, respectively. The ATP induced NO production was independent of N-methyl-D-aspartic acid (NMDA) receptor activity as effects were not alleviated by DL-2-Amino-5-phosphonopentanoic acid (APV), but antagonized by BBG. In sum, exogenous ATP elicited NO production in hippocampal neurons independently of NMDA receptor activity.为评估三磷酸腺苷（ATP）在海马体一氧化氮（NO）生成中的推定作用，本研究采用大鼠海马脑片与无胶质细胞的体外培养海马神经元作为实验模型。在海马脑片实验中，外源性添加ATP或2′(3′)-O-(4-苯甲酰苯甲酰)ATP（Bz-ATP）可引发浓度依赖性的NO生成，该生成过程在前15分钟呈线性上升，随后达到平台期；二者的半最大效应浓度（EC₅₀）分别为50 μM与15 μM。ATP诱导的NO生成升高可被考马斯亮蓝G（BBG）或Nω-丙基-L-精氨酸以浓度依赖性方式拮抗，分别提示P2X7受体（P2X7Rs）与神经元型一氧化氮合酶（neuronal NOS）的参与。ATP诱导的NO生成与N-甲基-D-天冬氨酸（NMDA）受体活性无关，因为其效应未被DL-2-氨基-5-膦酰戊酸（APV）削弱，反而可被BBG拮抗。综上，外源性ATP可独立于NMDA受体活性诱导海马神经元生成NO。