Effects of various frequency electrical stimulation of the dorsal raphe nucleus on spontaneous firing activities in the rat subthalamic nucleus★

BACKGROUND： Some investigations have demonstrated that exogenous 5-hydroxytryptamine increases the spontaneous firing rate of subthalamic nucleus （STN） neurons in the rat brain. OBJECTIVE： To validate the effect of electrical stimulation to the dorsal raphe nucleus （DRN） on the neuronal activities of the STN in rats, as well as analyze the differences in the effects of electrical stimulation at various frequencies. DESIGN, TIME AND SETTING： Experiments were performed from March 2007 to June 2007 in the Electrophysiology Laboratory of Liaoning Medical University with a randomized controlled animal study design. MATERIALS： Twenty-four healthy male Sprague-Dawley （SD） rats, weighing 250-350 g, were selected for this study. An A320R constant electrical stimulator was purchased from World Precision Instruments Company （USA）; a Spike 2 biological signal acquisition system was purchased from British CED Company. METHODS： Twenty-four SD rats were randomly assigned into a model group and a normal group, with 12 rats in each group. To mimic Parkinson＇s disease, rats in the model group were injected with 4μL of 6-hydroxydopamine into the right striatum, then received deep brain stimulation. Rats in the normal group received deep brain stimulation in same brain region without modeling. Electrical stimulation （width, 0.06 ms; intensity, 0.2-0.6 mA; frequency, 20-130 Hz; train duration, 5 seconds） was delivered to the DRN. MAIN OUTCOME MEASURES： The firing rates of STN neurons were observed by extracellular recording using a biological signal acquisition system. RESULTS： DRN-high-frequency stimulation （DRN-HFS） induced excitation in 59% of the STN neurons in the normal group and 50% of the STN neurons in the model group; mean firing rates increased significantly from （7.14±0.75） and （7.94 ± 0.61） Hz to （11.17 ±1.49） and （12.11 ± 1.05） Hz, respectively （P 〈 0.01）. Spontaneous firing rate increased significantly in 53% of neurons in normal rats in a frequency-dep

Effects of various frequency electrical stimulation of the dorsal raphe nucleus on spontaneous firing activities in the rat subthalamic nucleus

BACKGROUND: Some investigations have demonstrated that exogenous 5-hydroxytryptamine increases the spontaneous firing rate of subthalamic nucleus (STN) neurons in the rat brain.OBJECTIVE: To validate the effect of electrical stimulation to the dorsal raphe nucleus (DRN) on the neu-ronal activities of the STN in rats, as well as analyze the differences in the effects of electrical stimulation at various frequencies.DESIGN, TIME AND SETTING: Experiments were performed from March 2007 to June 2007 in the Electrophysiology Laboratory of Liaoning Medical University with a randomized controlled animal study design.MATERIALS: Twenty-four healthy male Sprague-Dawley (SD) rats, weighing 250-350 g, were selected for this study. An A320R constant electrical stimulator was purchased from World Precision Instruments Com-pany (USA); a Spike 2 biological signal acquisition system was purchased from British CED Company. METHODS: Twenty-four SD rats were randomly assigned into a model group and a normal group, with 12 rats in each group. To mimic Parkinson's disease, rats in the model group were injected with 4 μL of 6-hydroxydopamine into the right striatum, then received deep brain stimulation. Rats in the normal group re-ceived deep brain stimulation in same brain region without modeling. Electrical stimulation (width, 0.06 ms; intensity, 0.2-0.6 mA; frequency, 20-130 Hz; train duration, 5 seconds) was delivered to the DRN. MAIN OUTCOME MEASURES: The firing rates of STN neurons were observed by extracellular record-ing using a biological signal acquisition system. RESULTS: DRN-high-frequency stimulation (DRN-HFS) induced excitation in 59% of the STN neurons in the normal group and 50% of the STN neurons in the model group; mean firing rates increased significantly from (7.14± 0.75) and (7.94 ± 0.61) Hz to (11.17 ± 1.49) and (12.11 ± 1.05) Hz, respectively (P < 0.01). Spontaneous firing rate increased significantly in 53% of neurons in normal rats in a frequency-dependent manner when stimulation frequency was in the range 80-130 Hz.CONCLUSION: DRN-HFS induced an excitatory effect on the spontaneous activity of STN neurons in both normal and PD rats. There was a frequency-dependent effect of electrical stimulation of the DRN on sponta-neous firing activities in STN neurons.