大鼠前庭内侧核与前庭传出神经元间的直接投射通路及其电生理特性

Direct projection pathway between medial vestibular nucleus and vestibular efferent neurons in rats and its electrophysiological characteristics

目的证实新生大鼠前庭内侧核(MVN)与前庭传出(VE)神经元之间的直接投射通路并观察该通路的电生理特性。方法选用新生(9±1)d的Wistar大鼠,雌雄不限。通过全细胞膜片钳记录技术,刺激MVN,记录VE的突触后电流;逆行刺激脑干面神经膝部(g7)内侧VE的分布区,记录MVN区域传入神经元的动作电位,并使用生物胞素染色方法明确被记录的神经元的位置和形态。结果在电流钳记录中,位于g7内侧的VE神经元静息膜电位范围为-70--55 mV。单脉冲电流(0.08 mA,0.1 Hz,100μs)刺激MVN前庭传入神经元,在同侧g7内侧的VE神经元可记录到兴奋性突触后电流,其幅度和持续时间分别为(195.6±23.7)pA和(23.9±5.9)ms。电刺激g7内侧VE神经元分布区后,MVN神经元可记录到逆行动作电位,幅度为(62.0±4.3)mV,持续时间为(94.9±4.7)ms。生物胞素染色标记也显示投射到g7内侧VE分布区的神经元胞体位于MVN内。结论MVN的前庭传入神经元存在直接投射到g7内侧VE神经元的兴奋性通路,其生理功能可能与前庭中枢对外周前庭传入的反馈调节有关。

Objective To confirm the direct projection pathway between the medial vestibular nucleus(MVN)and vestibular efferent(VE)neurons and explore its electrophysiological characteristics.Methods Newborn[(9±1)day-old]male and female Wistar rats were used in the study.The postsynaptic currents of VE were recorded after stimulating neurons in MVN by the whole-cell patch clamp recording technique.The action potentials(APs)of the afferent neurons in MVN were recorded retrogradely after stimulating the area of VE neurons distribution medial to genu of facial nerve(g7),and the position and shape of the recorded neurons were determined by biocytin staining.Results The resting membrane potentials of VE neurons located medial to g7 ranged between-70 mV and-55 mV in current clamp recordings.Excitatory postsynaptic currents(EPSCs)were recorded in the VE neurons medial to the g7 evoked by single-pulse(0.08 mA,0.1 Hz,100μs)electrical stimulation of MVN.The mean values of amplitude and duration were(195.6±23.7)pA and(23.9±5.9)ms,respectively.APs were recorded in MVN after stimulating the distribution area of VE neurons.The mean amplitude of the action potentials was(62.0±4.3)mV,and the mean duration was(94.9±4.7)ms.Biocytin staining indicated that the recorded neurons located in MVN and the axons′terminals went into the area medial to g7 in which VE neurons located.Conclusions There is a direct excitatory pathway projecting from MVN to VE neurons medial to g7.Its physiological function may be related to the feedback regulation of vestibular center to peripheral vestibular afferent signals.