摘要
本研究通过制作急性水杨酸(salicylate acid,SA)大鼠耳鸣模型,观察电刺激初级听皮层(primary auditory cortex,AI)对下丘外侧核(external nucleus of inferior colliculus,ICx)放电活动的影响,探讨听觉的下行调控对耳鸣相关放电活动的作用。采用立体定位技术及细胞外记录方法,记录电刺激左侧AI后同侧ICx放电活动变化,用平均自发放电率和放电间隔直方图为观察指标。电刺激AI前、后持续记录急性SA模型大鼠同一ICx神经元自发放电。结果显示,电刺激AI对较高放电率的ICx神经元起抑制作用,对较低放电率的ICx神经元起易化作用。从ICx神经元平均自发放电率和短间隔放电比例来分析,电刺激AI后的4h观察时间内,对正常组与急性SA模型组大鼠ICx神经元放电均起抑制作用,而对急性SA模型组大鼠的抑制作用比对正常大鼠的抑制作用持久。上述结果提示,电刺激AI通过下行通路调控可在一段时间内抑制SA引起的与耳鸣相关的ICx放电活动。
This study aims to investigate corticofugal modulation on spontaneous activities of the external nucleus of the inferior colliculus （ICx） in a salicylate acid （SA） induced tinnitus rat model by the stimulation of the primary auditory cortex （AI）. Extracellular recording techniques and stereotaxic method were used. The spontaneous activities of a single unit were recorded from the left ICx after electrical stimulation was given to the left AI of the rats duplicated as acute SA models. The average rate of spontaneous discharge and the interspike interval histogram of spontaneous activities were used as indices. The single unit spontaneous discharges of the same unit of ICx before and after AI stimulation were observed. There was an inhibitory effect of AI stimulation on the activities of the high discharge unit [（8.75±2.70） Hz vs （5.06±2.01） Hz] and a facilitatory effect on the low discharge unit [（1.41±0.45） Hz vs （2.46±0.79） Hz]. In the normal group, there was a restraining effect on the average rate of spontaneous discharge of the ICx after AI stimulation. The average rate of spontaneous discharge changed from （3.66±0.84） Hz to （2.47±0.43） Hz in the first hour after AI stimulation and then recovered within 2-4 h. And the discharge rate of the spike interval within 0-20 ms decreased （17% vs 7.3%, 11.2%） in the first 2 h and recovered 3-4 h after AI stimulation. The discharge rate of the spike interval within 0-6 ms （short interval） recovered 2 h after AI stimulation. In the acute SA model group, the average rate of spontaneous discharge recorded from the ICx decreased from （7.48±0.85）Hz to （3.38±0.39） Hz in the first hour after AI stimulation and the suppression effect remained 4 h （P〈0.05）. There was no difference in the average rate of spontaneous discharge between the acute SA model group and the normal group at 2-4 h after AI stimulation. The suppression effect after AI stimulation on the 0-20 ms interval spikes in the ICx lasted 4 h, while that on the shorter interval （0-6 ms） spikes recovered in the 3rd hour after AI stimulation in acute SA model group. It is concluded that the high average spontaneous discharge rate of ICx in acute SA model decreases significantly by AI stimulation, and the suppression effects on the shorter interval spikes recovers in the 3rd hour after AI stimulation. It might be inferred that stimulation of AI, through exciting the auditory descending projections, could remit the increased spontaneous discharge of ICx induced by SA that may relate with tinnitus in a period of time.
出处
《生理学报》
CAS
CSCD
北大核心
2009年第2期121-126,共6页
Acta Physiologica Sinica
基金
supported by the "Shuguang" Project (No. O2SG47)
Leading Academic Discipline Project of Shanghai Munici-pal Education Commission
China (No. J50301)
关键词
水杨酸
初级听皮层
下丘外侧核
耳鸣
自发放电
离皮层调制
salicylate
primary auditory cortex
external nucleus of inferior colliculus
tinnitus
spontaneous activity
corticofugalmodulation
