Effect of scorpion venom analgesic active peptide extracted from Buthus martensii Karsch on evoked potential in the thalamic posterior nucleus group in rats

BACKGROUND： Buthus martensii Karsch is a rare medicinal animal, and dried integral Buthus rnartensii Karsch is an important drug in traditional Chinese medicine. OBJECTIVE： To investigate the effects of scorpion venom analgesic active peptide （SAP） extracted from Buthus martensii Karsch on evoked unit discharge of the common peroneal nerve in the posterior nucleus group of the thalamus using a stereotaxic electrophysiological extracellular microelectrode recording. DESIGN, TIME AND SETTING： One-way designed study, performed in the Physiological Laboratory of Shenyang Medical College on September 15, 2006. MATERIALS： Fifty 3-4 months old Wistar rats （25 males and 25 females） were used. SAP was provided by Shenyang Pharmaceutical University. Morphine solution was made by the First Drug Manufactory, Northeastern Drug Manufacture Group （batch number： H20013351）. Naloxone solution was made by Hunan Pharmaceutical Co., Ltd. （batch number： H43021669）. Type ATAC-350 medical data processing equipment was made by the Photoelectricity Company, Japan. METHODS： Fifty rats were randomly divided into the SAP group （n=20）, saline group （n=10）, morphine group （n=10）, or naloxone group （n=10）. In the SAP group, the common peroneal nerve was separated and stimulated with a single square wave （17-19 V intensity; 0.2 ms width; 20 ms retardation time）. Subsequently, SAP （0.01%, 2 μL） was injected into the posterior nucleus group of the thalamus. Rats in the naloxone group were injected with naloxone （1.0 mg/kg i.v.） before SAP injection. Rats in the saline group and the morphine group were injected with saline （2 μL） or morphine （0.01%, 2μL）, respectively, before SAP injection. Other procedures were the same as those in the SAP group. MAIN OUTCOME MEASURES： Evoked discharge in the posterior nucleus group of the thalamus and effects of SAP alone and SAP in combination with saline, morphine, or naloxone on discharges in the posterior nucleus group of the thalamus as measured by TQ-19 medical data processing equipment. RESULTS： SAP group： At 1-3 minutes after SAP injection, evoked discharges in the posterior nucleus group of the thalamus were inhibited, and the inhibitory time lasted for （45.0±0.7） minutes. Saline group： Evoked discharges in the posterior nucleus group of the thalamus did not change after saline injection. Morphine group： At 1-3 minutes after morphine injection, evoked discharges in the posterior nucleus group of the thalamus were inhibited, and the inhibitory time lasted for （35.0±7.8） minutes. Naloxone group： SAP had no effects on evoked potentials in the posterior nucleus group of the thalamus. CONCLUSION： The inhibitory effect of SAP on evoked potentials was superior to that of morphine at the same concentration （2 μL of 0.01% solution）. Naloxone resupination demonstrated that the inhibitory effects of SAP on evoked discharges were influenced by the opioid receptor.

Properties of oscillatory neuronal activity in the basal ganglia and thalamus in patients with Parkinson’s disease

Background:The cardinal features of Parkinson’s disease(PD)are bradykinesia,rigidity and rest tremor.Abnormal activity in the basal ganglia is predicted to underlie the mechanism of motor symptoms.This study aims to characterize properties of oscillatory activity in the basal ganglia and motor thalamus in patients with PD.Methods:Twenty-nine patients with PD who underwent bilateral or unilateral electrode implantation for subthalamic nucleus(STN)DBS(n=11),unilateral pallidotomy(n=9)and unilateral thalamotomy(n=9)were studied.Microelectrode recordings in the STN,globus pallidus internus(GPi)and ventral oral posterior/ventral intermediate of thalamus(Vop/Vim)were performed.Electromyography of the contralateral limbs was recorded.Single unit characteristics including interspike intervals were analyzed.Spectral and coherence analyses were assessed.Mean spontaneous firing rate(MSFR)of neurons was calculated.Analysis of variance and χ^(2) test were performed.Results:Of 76 STN neurons,39.5% were 4–6 Hz band oscillatory neurons and 28.9% were β frequency band(βFB)oscillatory neurons.The MSFR was 44.2±7.6 Hz.Of 62 GPi neurons,37.1% were 4–6 Hz band oscillatory neurons and 27.4% were βFB neurons.The MSFR was 80.9±9.6 Hz.Of 44 Vop neurons,65.9% were 4–6 Hz band oscillatory neurons and 9%were βFB neurons.The MSFR was 24.4±4.2 Hz.Of 30 Vim oscillatory neurons,70% were 4–6 Hz band oscillatory neurons and 13.3% were β FB neurons.The MSFR was 30.3±3.6 Hz.Further analysis indicated that proportion of βFB oscillatory neurons in STN and GPi was higher than that of similar neurons in the Vop and Vim(P<0.05).Conversely,the proportion of 4–6 Hz band oscillatory neurons and tremor related neurons in the Vim and Vop was higher than that of STN and GPi(P<0.05).The highest MSFR was for GPi oscillatory neurons whereas the lowest MSFR was for Vop oscillatory neurons(P<0.005).Conclusion:The alterations in neuronal activity in basal ganglia play a critical role in generation of parkinsonism.β oscillatory activity is more prominent in basal ganglia than in thalamus suggesting that the activity likely results from dopaminergic depletion.While both basal ganglia and thalamus have tremor activity,the thalamus appears to play a more important role in tremor production,and basal ganglia β oscillatory activity might be the trigger.