Effect Of Electrical Stimulation Of The Substantia Nigra Pars Reticulata On The Neuronal Activities Of Pedunculopontine Nucleus In PD Rats

ObjectivesTo observe the changes in neuronal activities of the pedunculopontine nucleus (PPN) after unilateral 6-hydroxydopamin (6-OHDA) lesioning of the substantia nigra pars compacta (SNc), and the effect of different frequency stimulation of the substantia nigra pars reticulata (SNr) on the firing rate of the PPN neurons in rats in order to investigate the mechanism of high frequency electrical stimulation of SNr for the treatment of parkinson's disease.MethodsTo record extracellular single unitary neuronal activities of the PPN, and to observe the changes of the firing rate of the PPN caused by different frequency stimulation of SNr (5-200Hz), microiontophoresis of Glu and GABA of their antagonists respectively and the high frequency stimulation of SNr in control and PD rats.ResultsThe firing rate of the PPN neurons in regular pattern significantly increased in 6-OHDA lesioned rats and the firing pattern of the PPN neurons changed towards more irregular and bursty compared with the control rats. SNr stimulations at low frequency(5-10Hz)could not affect the spontaneous firing activities of PPN neurons ( P>0.05). With the increase of stimulation frequency(20-200Hz), the majority of neurons recorded in the PPN were inhibited. Glu had a tonic excitatory effect whereas GABA had a tonic inhibitory effect on the PPN neurons. The microiontophoresis of BIC could suppress the inhibitory effect of high frequency stimulation of SNr on the PPN neurons. ConclusionsThe firing rate of the PPN neurons in regular pattern in the PD rat was significantly higher than that of the control rat and the firing pattern of the PPN neurons changed towards more irregular and bursty compared with the control rats. The majority of neurons recorded in the PPN were inhibited by SNr high frequency stimulation. Glu had a tonic excitatory effect whereas GABA had a tonic inhibitory effect on the PPN neurons. The microiontophoresis of BIC could suppress the inhibitory effect of high frequency stimulation of SNr on the PPN neurons. These results suggest that the effect of SNr high frequency stimulation on PD is realized partly by inhibiting the neuronal activity of PPN.