丙泊酚对大鼠下丘神经元放电阈值的影响

Effect of propofol on minimum threshold of inferior collicnius neuron discharge in rats

目的探讨丙泊酚麻醉对大鼠下丘神经元放电阈值的影响。方法取SPF级SD大鼠43只，腹腔注射维库溴铵维持肌松，呼吸机进行机械通气，将玻璃微记录电极刺人大鼠下丘中央核（ICC），采用TDT3听觉研究系统、细胞外记录的方式研究丙泊酚麻醉（100mg／kg腹腔注射）前后下丘神经元放电阈值的变化。结果神经元的特征频率[（12．06±8．77）kHz]和记录电极深度[（3435．65±651．00）μm]呈正相关关系（r=0．581，P=0．000）。43个神经元中30个可以明确其放电阈值，清醒和麻醉状态下放电阈值分别为（36．8±20．41、（40．4±20．5）声压级（dBSPL），比较差异有统计学意义（P〈0．05）；清醒和麻醉状态下最小阈值的散点图进行线性拟合所得直线的截距与对角线比较差异有统计学意义（P〈0．05）。结论丙泊酚麻醉使下丘神经元放电阈值提高，兴奋性降低，这可能是丙泊酚麻醉影响听觉信息传递的重要原因。

Objective To evaluate the effect ofpropofol on minimum threshold （MT） of the inferior colliculus neuron discharge in rats. Methods Forty-three healthy SPF grade Sprague Dawley （SD） rats, weighing 200-250 g, were chosen in our study and established wakeful animal models by ventilating with animal respirator after infusing vecuronium. A microelectrode was penetrated in the inferior colliculus （ICC）, and then, MT of the inferior colliculus neuron discharge was noted using a Tucker-Davis Technologies System 3 before intraperitoneal injection of propofol 100 mg/kg and after administration. Results Characterizing frequency of the neurons （12.06±8.77 kHz） was positively correlated to depth of the recording electrode （3435.65±651.00 μm; r=0.581, P=0.000）; discharge threshold can be determined in 30 of 43 neurons, and the threshold values under awake and anesthetized states were 36.8±20.4 dB SPL and 40.4±20.5 dB SPL, respectively, with significant differences （P〈0.08）. The intercept of the linear regression line is significantly more than 0 corresponding to the diagonal one （P〈0.05）. Conclusion Propofol affect auditory information transmission by increasing neuronal response MT and reducing excitability in ICC, which is possibly an important factor leading to hearing disappear.