Study On The Subthalamic Neuronal Activities In A Rat Model Of Parkinson's Disease

Objective: To establish the rat model of Parkinson's disease(PD)induced with 6-hydroxydopamine(6-OHDA) and study the change of theelectrophysiology of the subthalamic nucleus(STN) to make thepathophysiological mechanism of PD clear.Methods: Seventeen male SD rats were divided into control group(n=7)and experimental group(n=10).Stereotaxic injection of 6-OHDA into theleft substantia nigra pars compacta(SNc) of rats in the experimentalgroup to develop rat model of PD. Four weeks after the injection, therats were intraperitoneally given apomorphine(APO)O. Smg/kg forbehavioral analysis. A successful rat model was considered when the levelof continuous right turning induced by APO above 7 turns/min in 30 minutes.Extracellular single-unit recordings of STN neurons were performed incontrol and PD rats using glass micropipettes. Then the rats' brains wereremoved and stained With hematoxylin and eosin(HZ). The location in theSTN of all these neurons and the lesion of SNc neurons were supportedby the histological verifications. And the discharge rates and patternswere analyzed by the Spike 2 analysis software.Results:Among the 10 rats of experimental group, 6 rats showed successfulAPO-induced rotation and one dead. The success ratio of PD model was60%.A total of 20 neurons were analysed in control group and 37 in PDrats. Histological sections showed all the recording sites were locatedin the STN. In the PD rats, sections showed disorder of structure, lossof neuronal bodies and hyperplasia of gliocytes in the lesion side of SNc, while the SNc neurons of the other, side showed integrated structure.The discharge rates of the STN neurons in control and PD rats were16.18±10.67 Hz and 17.74±11.20 Hz,respectively. They had no obviousdifference(P＞0.05). In control group, STN neurons displayed three:typesof discharge patterns—3 neurons(15%) discharged regularly,10irregularly(50%)and 7 (35%) in bursts. In PD rats, however, 5neurons(13.5%) discharged regularly, 6 irregularly(16.2%) and 26(70.3%)in bursts. The percentage of the neurons discharging in burstswas higher than that of the control rats, While the percentage of theneurons discharging irregularly was lower than that of the controlrats (P＜0.05).Conclusions:1. The rat model of PD induced by 6-OHDA which was injected in twosites of the SNc is a good animal model which can simulate thecharacteristics of human PD. And in this research the success ratio ofPD model was higher than that of the traditionary methods.2. This research showed in the PD conditions the discharge rate ofSTN neurons had no obvious difference with that of the control group,while the percentage of the neurons discharging in bursts was higher thanthat of the control group. The results indicated STN neurons showedoveractivity in the PD conditions.3. This research suggested suppressing STN pathological activity andreestablishing the normal patterns of activity within the basal gangliashould be pathophysiological bases of PD treatment.4. The research provided both STN lesions and high frequencystimulation for PD therapy with theoreticalbases. The metheods have been proposed to suppress STN pathological activity and reestablish the normalpatterns of activity within the basal ganglia.