Wireless Telemetry Electrical Activity On Medial Prefrontal Cortex Of Heroin-induced CPP Rats:Characterisitic Of Theta Oscillation On Prelimbic Cortex

As a rhythmic neural activity,neural oscillation,theta oscillationespecially existed in medial prefrontal cortex(m PFC).Preceding studies suggests a close link between working memory(WM)processes and low theta rhythms(4~8 Hz)of rat m PFC.However,The theta oscillation whether or not exists in prelimbic(PrL)area of m PFC,and the relationshipbetween The theta oscillation of PrL area and the drug-seeking behavior of heroin-induced conditioned place preference(CPP)rats has not been investigated yet.the present study detected the neural oscillation activity of rat’s PrL area during drug-seeking procedure.The recording electrode was stereotactically implanted into the PrL cortex of rats.The animals were then divided randomly into operation-only control and heroin-induced CPP groups,respectively.A CPP video system in combination with an wireless telemetry device was used for recording LFPs of PrL area when the rats shuttled between black-whitechamber for drug-seeking.The LFPs were analyzed by fast Fourier transform and wavelet packet extraction.Compared with operation-only control group,the LFPs recorded in PrL area of heroin-induced CPP group of rat during black-white chamber shuttling showed that the percentage of θ rhythmwere increased in right and left PrL(P<0.05),the percentage of γ3 rhythm was increased in left PrL(P<0.05),which were accompanied by the percentage of α,γ1 rhythm decline in left PrL(P<0.01,P<0.05)and β rhythm decline in right PrL(P<0.05).After MK-801 Maleate micro injection to PrL area,drug-seeking behaviour of rat was markedly reduced and the percentage of θ oscillation was reversal depression,while else rhythms were no observably difference compared with operation-only control group.Further wavelet analysis of θ rhythm constituents found that the percentage and amplitude of 4 ~ 5Hz were increased in right and left PrL,meanwhile amount of the large amplitude(intensity:+1 ~-1db)waves were also increased compared with operation-only control group(P<0.05,P<0.01).These results suggest that increase of θ oscillations of PrL area,particular large amplitude waves of 4~5Hzconstituents may be related to rat’s drug-seeking motivation and behavior launchingin heroin-induced CPP groups of rat.The result of immunohistochemistry show that Compared with operation-only control group PSD-95 fromheroin-induced CPP group was increased in PrL,which after MK-801 Maleate micro injection to PrL area the change was reversed(P<0.05,P<0.01).The changes of θ oscillations also implicated have close relationship with glutamatergic neuron and the receptor of it on PrL area.