Effect Of Electrical Stimulation Of Pedunculopontine Nucleus On Neuronal Activity In Subthalamic Nucleus And Globus Pallidus Internus Of PD Rats

ObjectivesTo investigate the effect of deep brain stimulation （DBS） ofpedunculopontine nucleus（PPN）on the neuronal activities of Subthalamicnucleus（STN） and globus pallidus internus （Gpi） in rats of parkinson’sdisease as well as the underlying the mechanism involved. To provide scientificevidence in electrophysiology for therapy of parkinson’s disease.MethodsParkinson’s disease（PD）model rats were established by the injection of6-OHDA into SNc with stereotactic technique on the right side of the brain. Torecord extracellular single unitary neuronal activities of STN and GPi, and toobserve the changes of the firing rate of STN and GPi. Electrophysiologicalrecordings were made in anaesthetized rats to investigate the effects of highfrequency stimulation （HFS） of PPN and low frequency stimulation （LFS）of PPN on the firing rate of the GPi neurons.Results1．The firing pattern of the STN and GPi neurons changed towards moreirregular and bursty compared with the control rats （P＜0.05）. There are threekinds of response of STN and GPi neurons to STN-DBS （excitation, inhibitionand no response）.2．PPN-LFS for5seconds increases the firing rate of30%（6/20） STNneurons in control rats and12.5%（3/24）STN neurons in PD rats, and decreases the firing rate of55%（11/20） STN neurons in control rats and66.67%（16/24） STN neurons in PD rats （P＜0.05）; PPN-HFS for5secondsincreases the firing rate of50%（10/20） STN neurons in control rats and54.17%（13/24）STN neurons in PD rats, and decreases the firing rate of20%（4/20）STN neurons in control rats and20.83%（5/24） STN neurons in PDrats （P＜0.05）.3．PPN-LFS could not affect the spontaneous firing activities of GPineurons （P>0.05）. PPN-LFS for5seconds could not affect the firing rate of52.63%（10/19）GPi neurons in control rats and57.69%（15/26）GPi neuronsin PD rats; PPN-HFS for5seconds increases the firing rate of94.74%（18/19）GPi neurons in control rats and69.23%（18/26）GPi neurons in PD rats, anddecreases the firing rate of0.00%（0/19）GPi neurons in control rats and11.54%（3/26）GPi neurons in PD rats（P＜0.01）.Conclusions1．The firing pattern of the STN and GPi neurons changed towards moreirregular and bursty compared with the control rats.2．The majority of neurons recorded in the STN were inhibited by PPN-LFS.The majority of neurons recorded in the STN were excited by PPN-HFS.3．PPN-LFS could not affect the spontaneous firing activities of GPineurons. The majority of neurons recorded in the GPi were excited byPPN-HFS.These results suggest that low frequency stimulation of the PPN has a rolein the therapy for Parkinsonism, and the effect of PPN high frequencystimulation on PD is realized partly by inhibiting the neuronal activity of STN.