Regulation of Pain via NMDA receptor-NO-cGMP pathway in the spinal cord

利用一氧化氮和谷氨酸微传感器，研究了大鼠脊髓背角一氧化氮和谷氨酸在体内和体外（薄片制备）中的关系。结果表明，虽然在体内证明谷氨酸微传感器没有足够的灵敏度，但在大鼠足部注射马林后，一氧化氮微传感器显示脊髓背角一氧化氮浓度呈双相增加。这两种反应都被预先给予7-硝基茚唑抑制，据报道，7-硝基茚唑是神经元一氧化氮合酶（nNOS）的特异性抑制剂。相比之下，预先给药MK8O1并没有抑制有害刺激后一氧化氮的第一次增加，尽管它抑制了第二次反应。这些结果表明，一氧化氮的第一次增加来自背根神经节细胞，第二次反应来自背角神经元。一氧化氮在脊髓中的作用以及一氧化氮与谷氨酸之间的关系仍在研究中。

The relationship between nitric oxide and glutamic acid in the dorsal horn of rat spinal cord were investigated in vivo and in vitro (slice preparation) using microsensors for nitric oxide and glutamic acid. As a result, although the microsensor for glutamic acid was proved not to have enough sensitivity in vivo, the sensor for nitric oxide showed biphasic increase of nitric oxide concentration in the dorsal horn of the spinal cord after for malin injection in the rat paw. The both responses were inhibited by pre-administration of 7-nitroindazole, which is reported to be a specific inhibitor of neuronal nitric oxide synthase (nNOS). In contrast, pre-administration of MK8O1 did not inhibit the first increase of nitric oxide after noxious stimuli, although it inhibited the second response. These reisults suggest that the first increase of nitric oxide was derived from dorsal root ganglion cells and the second response of nitric oxide was from dorsal horn neurons. The role of the nitric oxide in the spinal cord and the relationship between nitric oxide and glutamic acid are still under investigation.