Hämäläinen M M, Lovick T A
Department of Physiology, University of Birmingham, U.K.
Neuroscience. 1997 Oct;80(3):821-7. doi: 10.1016/s0306-4522(97)00124-3.
In rats anaesthetized with alphaxalone/alphadolone, electrical stimulation in the periaqueductal gray matter in the region lying lateral and dorsolateral to the aqueduct produced a pressor response and an increase in the latency of the tail flick response to noxious heat applied to the tail. The antinociception and the pressor response were significantly attenuated following microinjection of 15 nmol 5-hydroxytryptamine at the site of stimulation in the periaqueductal gray matter. Microinjection of an equal volume of 165 mM saline had no effect. The inhibitory effects of 5-hydroxytryptamine were blocked by prior intracerebroventricular administration of 100 microg of the nitric oxide synthase inhibitor L-nitroarginine methyl ester. Neither 5-hydroxytryptamine or L-nitroarginine methyl ester had any effect on resting arterial pressure or on the baseline latency of the tail flick reflex. It is suggested that the inhibitory effects of 5-hydroxytryptamine in the dorsolateral periaqueductal gray matter are normally dependent on the functional integrity of local nitric oxide synthase-containing interneurons. Nitric oxide may act in association with 5-hydroxytryptamine to control the excitability of the aversive system in the midbrain.
在用α-羟孕酮/α-多沙普仑麻醉的大鼠中，对导水管外侧和背外侧区域的导水管周围灰质进行电刺激，会产生升压反应，并使对施加于尾部的有害热刺激的甩尾反应潜伏期延长。在导水管周围灰质刺激部位微量注射15 nmol 5-羟色胺后，抗伤害感受和升压反应均显著减弱。注射等体积的165 mM生理盐水则无影响。预先脑室内注射100 μg一氧化氮合酶抑制剂L-硝基精氨酸甲酯可阻断5-羟色胺的抑制作用。5-羟色胺或L-硝基精氨酸甲酯对静息动脉血压或甩尾反射的基线潜伏期均无影响。提示5-羟色胺在背外侧导水管周围灰质中的抑制作用通常依赖于含一氧化氮合酶的局部中间神经元的功能完整性。一氧化氮可能与5-羟色胺共同作用，以控制中脑厌恶系统的兴奋性。
