硝普钠对离体视上核神经元的抑制和兴奋作用1

目的 观察NO 供体硝普钠(SNP) 对视上核(SON) 神经元的影响, 以了解NO 对SON 细胞活动的调节作用。方法 对成年大鼠下丘脑切片SON神经元进行细胞内生物电记录, 测定细胞电生理参数。结果 在11 个安静的细胞灌流给药SNP(1 m mol·L^-1) 3 ~ 5 min, 使55 %的细胞发生去极化(P <0.05), 伴有膜电阻和时间常数减小, 而使45 %的细胞超极化(P <0.05) 。SNP 使73 %细胞的诱发动作电位的幅度和超射值减小、半幅时程增大(P <0.05), 并伴放电频率降低、电流_电压曲线斜率减小、AHP幅度增大(P <0.05);但在6 个有自发性放电的细胞, SNP使67 %细胞的自发性放电频率升高(P <0.05)。结论 SNP 能细胞类型和功能状态依赖性地对SON 神经元产生兴奋性或抑制性影响, 提示NO 对SON 细胞活动有不同的调节作用。

Inhibitory and excitatory effects of sodium nitroprusside on supraoptic nucleus neurons in vitro1

Aim To realize the regulatory actions of nitric oxide (NO) on supraoptic nucleus (SON) neurons by observing the effects of NO donor sodium nitroprusside (SNP) on SON neurons. Methods The cell electrophysioloical properties were obtained by the intracellular recording techniques from the SON neurons in adult rat hypothalamic slices. Results In 11 silent cells, superfusion of SNP(1 m mol·L^-1) for 3?5 min resulted in the depolarization response with a decrease of membrane resistance and time constant CP <0.05) in 55 % of cells while hyperpolarization with an increase of membrane resistance in 45% of neurons. In 73% of tested cells, SNP also decreased the amplitude, overshoot, firing frequency and slope of current voltage curve and increased the after hyperpolarization of action potentials evoked by intracellular depolarizing current pulses (P <3.05).However, SNP enhanced the spontaneous firing in 67% of 6 tested cells with spontaneous activities. Conclusion SNP presents an inhibitory or excitatory effect on SON neurons in a neuron type-and functional state-dependent manner, which suggests that NO may exhibit adverse regulatory actions on SON neurons.