The Role Of Glutamatergic Neurons In Piriform Cortex In The Change Of Consciousness Induced By General Anesthesia

Objective:The piriform cortex(PC)is an important nucleus in the olfactory circuit.It is involved in the analysis and transmission of odors,and can regulate panic,learning and memory,control epileptic seizures,and regulate sleep functions.PC is structurally divided into anterior piriform cortex(APC)and posterior piriform cortex(PPC).PC neurons consist of a large number of glutamatergic neurons and a small amount of GABA(gamma-aminobutyric acid)neurons.In the previous study of our laboratory,it was found a dramatic increase of c-Fos expression in PC under the action of inhalation anesthetic isoflurane,indicating that PC neurons were greatly activated after isoflurane anesthesia.Whether PC is involved in the process of general anesthesia and its mechanism are still unclear.In order to determine whether PC is involved in the process of general anesthesia,this study adopted: 1.For c-Fos staining,the brains were perfused after isoflurane and propofol anesthesia,respectively,and c-Fos and Neu N staining were performed.2.To observe the behavioral changes of mice anesthetized with isoflurane and propofol by destroying APC and PPC neurons with chemical drugs;3.Using chemical genetics to regulate APC neurons,recording behavioral and cortical EEG(Electroencephalography)changes in mice under propofol and isoflurane anesthesia;4.Specifically activate APCGlu neurons,and record the behavioral,EEG and EMG(Electromyogram)changes of mice under isoflurane、sevoflurane and propofol anesthesia;5.Optogenetically activate APCGlu neurons,and observe the changes of LORR,RORR,EEG and EMG in mice during isoflurane、sevoflurane and propofol anesthesia;6.Explore the upstream and downstream nuclei of APC.Objective to explore the the mechanism of PC in general anesthesia.Methods:1.c-Fos staining: c-Fos staining: C57BL/6J mice were selected and divided into wake group,isoflurane/propofol group and recovery group randomly.Isoflurane group:continuous inhalation of isoflurane(1.4 %),brain perfusion after 120 minutes,propofol group: propofol(6 mg/kg/min)was injected via tail vein in mice,brain perfusion was120 minutes after injection;By counting c-Fos,the effects of isoflurane/propofol-induced anesthesia on the activity of the Glutamatergic neurons.2.Use chemical drugs to damage PC neurons,observe and record the behavior of mice under isoflurane and propofol anesthesia.3.Using chemogenetics to activate APC neurons,observe the behavioral and EEG changes of mice under isoflurane and propofol anesthesia.4.Using specific chemogenetics to activate APCGlu neurons,observe the behavioral and EEG changes of mice under isoflurane、sevoflurane and propofol anesthesia.5.Optogenetically activate APCGlu neurons,and observe the changes of LORR,RORR,EEG and EMG in mice during isoflurane、sevoflurane and propofol anesthesia6.Inject CTB and AAV-h Syn-Ch R2-EYFP viruses into APC to explore the upstream and downstream nuclei of PC.Results:1.2 h after isoflurane and propofol anesthesia,c-Fos in PC was greatly increased and 2 h after anesthesia,c-Fos was decreased again;the expression of c-Fos and Neu N is co-localized.It is suggested that PC is involved in the process of isoflurane and propofol anesthesia.2.After the APC of the mice was damaged,the LORR of isoflurane anesthesia was significantly shortened(p<0.01),the RORR of isoflurane anesthesia had no significant change,and the RORR of propofol anesthesia had no significant change;after PPC damage,there was no obvious change in the behavior of mice after isoflurane and propofol anesthesia.3.Activated of APC neurons,isoflurane anesthesia significantly shortened the LORR(p<0.01),the corresponding cortical delta wave(1-4 Hz)was weakened(p<0.05),and the beta wave(12-25 Hz)was enhanced(p<0.05),isoflurane anesthesia has no significant change in RORR,and the corresponding EEG has no significant change;propofol anesthesia has no significant change in RORR,and there is no significant difference in the corresponding EEG.4.Prolonged activated APCGlu neurons,isoflurane anesthesia significantly prolonged LORR(p<0.05),while RORR did not change,corresponding to an increase in EEG delta wave power(p<0.05);Sevoflurane anesthesia significantly prolonged LORR(p<0.001),corresponding to an increase in EEG delta wave power and a decrease in gamma wave power(p<0.05);Propofol anesthesia had no significant changes in LORR and RORR,corresponding to no significant changes in EEG.5.Immediate activation of APCGlu neurons,isoflurane anesthesia significantly prolonged LORR(p<0.05),while RORR did not change,and the corresponding EEG had no significant difference;The LORR of sevoflurane anesthesia was significantly prolonged(p<0.05),while the RORR did not change,corresponding to no significant difference in EEG;Propofol anesthesia had no significant change in LORR and RORR,and the corresponding EEG had no significant change.6.Tracer results: After the PC was injected with retrograde tracer virus(CTB),the red color carried by the virus was observed in the anterodorsal thalamic nucleus(AD)and the bed nucleus of the commissure(BAC).After the PC was injected with anterograde tracer virus(AAV-h Syn-Ch R2-EYFP)was injected into the PC,and green fluorescence was observed IL.Conclusion:1.Isoflurane and propofol activate PC neurons,and isoflurane activates PCGlu neurons,suggesting that PC is involved in isoflurane and propofol anesthesia;2.APC neurons are involved in the regulation of isoflurane anesthesia induction,and activation of APCGlu neurons prolongs isoflurane and sevoflurane anesthesia induction time,suggesting that APCGlu neurons regulate isoflurane and sevoflurane anesthesia induction;3.Preliminarily found that the upstream nuclei of PC,AD and BAC,and the downstream nuclei IL.