| Deep brain stimulation（DBS）represents an effective technique for the treatment of Parkinson’sdisease（PD）by electrical stimulating specific nucleuses. Subthalamic nucleus（STN）is the preferredtarget of DBS, high-frequency stimulation of this nucleus improves all cardinal features of PD,including resting tremor. However, the underlying therapeutic mechanisms remain undefined.PD rat model was induced by 6-hydroxydopamine（6-OHDA）in this study. The microelectrodeswere implanted to record local field potentials（LFPs）in STN and primary motor cortex（M1）of PD andnormal rats in different states. Then LFPswas imported into Matlab and SPSS to be analysisprocessed.By revealing the changing regularities of discharge pattern in STN and M1 and their relevance in PDrats, this study is to provide theories for clarifying therapeutic mechanism of STN DBS.PD rat model was constructed by stereotaxic injecting 6-OHDA into substantia nigra parscompacta（SNc）and ventral tegmental area in this study. The success rate of this method could reach upto 65% induced by Apomorphine. Coronal sections of midbrain in PD rats showed that there were agreat quantity of apoptotic dopaminergic neurons in SN_c, just like the histologic characteristics ofprimary PD.High amplitude and a number of areatus discharges were the main wave characteristics of LFPsinSTN of anaesthetic PD rats. Spectral decomposition showed the whole frequency of LFPsin STN of PDrats was higher than that of normal rats. Power spectral density analysis showed the power of highfrequency（especially at 15 Hz to 30 Hz）LFPsin STN of PD rats was increased. More energy could beobserved in spectrogram of LFPsin STN of PD rats. All the results above suggest that the electricalactivity of STN is erethism in PD rats in anaesthetic state.The wave pattern of LFPsin M1 of two groups changed regularly in motorial state. LFPsin M1 could be divided into four periods called grabbing prophase, planning period, grabbing period andcomplete period in the whole process of grabbing food. Different wave patterns could be observed indifferent periods. Spectral decomposition showed the whole frequency of LFPs in M1 of PD ratsbecame higher in grabbing period. Power spectral density analysis showed the power of high frequency（30~100Hz）LFPs in M1 of PD rats was increased when rats were grabbing food. More energy couldbe observed in spectrogram of LFPs in M1 of PD rats in grabbing period. These results suggest that thechange in electrical activity of M1 closely associates with behaviour of animals, the electrical activity ofM1 is erethism in PD.The cross-correlation and phase of LFPs in STN and M1 synchronous recorded were analysised.Both of them showed the relevance of LFPs in these two brain areas of PD rats was less than that ofnormal rats in different state. This suggests the neural passway between STN and M1 is damaged insome degree in PD. The relevance of PD rats decreased significantly in anaesthetic state, which may becaused by the overactive STN and resting M1. The emergence of LFPs in M1 was delayed after LFPs inSTN, the electrical activity of M1 was induced by STN. It suggests STN feedback regulates M1 in somedegree.Conclusion：Injecting 6-OHDA into two brain areas is an ideal method to construct PD rat model.The electrical activity of STN is erethism in anaesthetic PD rats. The change of wave pattern of LFPs inM1 closely associates with behaviour of animals, the electrical activity of M1 is erethism in PD. Theelectrical activity of M1 is induced by STN, and this function is weaken in PD. |
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