BACKGROUND： Subthalamic nucleus-high frequency stimulation （STN-HFS） plays an important role in the treatment of Parkinson＇s disease, but the mechanisms underlying STN-HFS remain unclear. Some studies have demonst...BACKGROUND： Subthalamic nucleus-high frequency stimulation （STN-HFS） plays an important role in the treatment of Parkinson＇s disease, but the mechanisms underlying STN-HFS remain unclear. Some studies have demonstrated that STN stimulation inhibits the firing activity of substantia nigra pars reticulata neurons. OBJECTIVE： To investigate the effects of different-frequency STN stimulation and microiontophoresis of gamma-aminobutyric acid （GABA） and its antagonist, bicuculline, on spontaneous firing activity in a rat model of Parkinson＇s disease, and to analyze the action pathway of high frequency stimulation in firing activity inhibition of substantia nigra pars reticulata neurons. DESIGN, TIME AND SETTING： This neuroelectrophysiological, animal experiment was performed at the Electrophysiology Laboratory of Liaoning Medical University, China from March to August 2008. MATERIALS： 6-hydroxydopamine （6-OHDA） （Sigma, USA）, A320R isolated stimulus and DAM80 preamplifier （World Precision Instruments, USA）, 6400A microiontophoresis apparatus （Dagan, USA）, and Spike 2 biological signal acquisition system （CED, UK） were used in this study. METHODS： A total of 20 Sprague Dawley rats were used to establish a Parkinson＇s disease model via injection of 6-OHDA into the right striatum. Electrical stimulation （0.06-ms width, 0.4-mA intensity 20-200-Hz frequency, 5-second train duration） was delivered to the subthalamic nucleus. Peripheral channels were separately filled with GABA （pH 3.5, 0.2 mol/L）, bicuculline （pH 4.0, 0.01 mol/L）, and NaCI （pH 7.0, 3 mol/L）. The electrode was positioned with a WK-2 microelectrode propulsion device, and was slowly inserted into the substantia nigra pars reticulata to record spontaneous firing activity of substantia nigra pars reticulata neurons. MAIN OUTCOME MEASURES： The number and firing rate of substantia nigra pars reticulata neurons which were either inhibited or excited were measured. RESULTS： Substantia nigra pars reticulata neurons were inhibited by STN stimulation. The proportion of inhibited substantia nigra pars reticulata neurons increased with increasing stimulation frequency. GABA had a tonic inhibitory effect on substantia nigra pars reticulata neurons. Microiontophoresis of bicuculline suppressed the inhibitory effect of STN-HFS on 67% （4/6） of substantia nigra pars reticulata neurons. CONCLUSION： STN-HFS ameliorated abnormal activity in substantia nigra pars reticulata neurons via the inhibitory effect of GABA treatment in a rat model of Parkinson＇s disease.展开更多
文摘BACKGROUND： Subthalamic nucleus-high frequency stimulation （STN-HFS） plays an important role in the treatment of Parkinson＇s disease, but the mechanisms underlying STN-HFS remain unclear. Some studies have demonstrated that STN stimulation inhibits the firing activity of substantia nigra pars reticulata neurons. OBJECTIVE： To investigate the effects of different-frequency STN stimulation and microiontophoresis of gamma-aminobutyric acid （GABA） and its antagonist, bicuculline, on spontaneous firing activity in a rat model of Parkinson＇s disease, and to analyze the action pathway of high frequency stimulation in firing activity inhibition of substantia nigra pars reticulata neurons. DESIGN, TIME AND SETTING： This neuroelectrophysiological, animal experiment was performed at the Electrophysiology Laboratory of Liaoning Medical University, China from March to August 2008. MATERIALS： 6-hydroxydopamine （6-OHDA） （Sigma, USA）, A320R isolated stimulus and DAM80 preamplifier （World Precision Instruments, USA）, 6400A microiontophoresis apparatus （Dagan, USA）, and Spike 2 biological signal acquisition system （CED, UK） were used in this study. METHODS： A total of 20 Sprague Dawley rats were used to establish a Parkinson＇s disease model via injection of 6-OHDA into the right striatum. Electrical stimulation （0.06-ms width, 0.4-mA intensity 20-200-Hz frequency, 5-second train duration） was delivered to the subthalamic nucleus. Peripheral channels were separately filled with GABA （pH 3.5, 0.2 mol/L）, bicuculline （pH 4.0, 0.01 mol/L）, and NaCI （pH 7.0, 3 mol/L）. The electrode was positioned with a WK-2 microelectrode propulsion device, and was slowly inserted into the substantia nigra pars reticulata to record spontaneous firing activity of substantia nigra pars reticulata neurons. MAIN OUTCOME MEASURES： The number and firing rate of substantia nigra pars reticulata neurons which were either inhibited or excited were measured. RESULTS： Substantia nigra pars reticulata neurons were inhibited by STN stimulation. The proportion of inhibited substantia nigra pars reticulata neurons increased with increasing stimulation frequency. GABA had a tonic inhibitory effect on substantia nigra pars reticulata neurons. Microiontophoresis of bicuculline suppressed the inhibitory effect of STN-HFS on 67% （4/6） of substantia nigra pars reticulata neurons. CONCLUSION： STN-HFS ameliorated abnormal activity in substantia nigra pars reticulata neurons via the inhibitory effect of GABA treatment in a rat model of Parkinson＇s disease.
