Baskys A, Niesen C E, Davies M F, Carlen P L
Playfair Neuroscience Unit, Toronto Western Hospital, Addiction Research Foundation, Ontario, Canada.
Neuroscience. 1989;29(2):443-51. doi: 10.1016/0306-4522(89)90071-7.
Pressure ejection of serotonin (2 x 10(-4) M) onto dentate granule neurons in vitro produced a short-lasting membrane hyperpolarization associated with a 10-30% decrease in the input resistance. The hyperpolarization magnitude depended on the extracellular K+ concentration but not on the extra or intracellular Ca2+ concentration. It was followed by a depolarization, especially when serotonin was applied onto the perisomatic area of the neuron. The post-spike-train afterhyperpolarization, which represents a Ca2+-dependent K+ conductance, was decreased by serotonin by 10-100% and remained reduced for 2-10 min following the serotonin-induced hyperpolarization. Decreased adaptation of cell firing was also observed following serotonin application. Ca2+ action potentials evoked by intracellular depolarizing current pulses in the presence of the Na+ channel blocker tetrodotoxin and the K+ channel blocker tetraethylammonium were followed by a large afterhyperpolarization, which was markedly reduced for several minutes following serotonin application. The preceding Ca2+ action potential was either unaffected or prolonged. The hyperpolarization occurring in response to localized application of serotonin, and the reduction of the afterhyperpolarization, may represent two different mechanisms of serotonin action, probably mediated by different mechanisms. The slow time course of the late depolarization and the afterhyperpolarization depression represent modulatory effects of serotonin on dentate granule neurons.
在体外将血清素（2×10⁻⁴ M）压力喷射到齿状颗粒神经元上，会产生短暂的膜超极化，同时输入电阻降低10 - 30%。超极化幅度取决于细胞外钾离子浓度，而不取决于细胞外或细胞内钙离子浓度。随后会出现去极化，尤其是当血清素作用于神经元的胞体周围区域时。代表钙依赖性钾离子电导的峰后串后超极化，被血清素降低了10 - 100%，并且在血清素诱导的超极化后2 - 10分钟内持续降低。血清素作用后还观察到细胞放电适应性降低。在存在钠离子通道阻滞剂河豚毒素和钾离子通道阻滞剂四乙铵的情况下，细胞内去极化电流脉冲诱发的钙动作电位之后会出现大幅度的后超极化，血清素作用后几分钟内该后超极化明显降低。之前的钙动作电位要么未受影响，要么延长。因血清素局部作用而发生的超极化以及后超极化的降低，可能代表血清素作用的两种不同机制，可能由不同机制介导。晚期去极化和后超极化抑制的缓慢时间进程代表血清素对齿状颗粒神经元的调节作用。
