| Objective Myocardial ischemia-reperfusion injury(MIR/I)is a hot issue in the diagnosis and treatment of critical diseases.At present,the central regulatory mechanism of MIR/I is not completely clear.This experiment intends to investigate the neuron transfer of neurotransmitter ?-aminobutyric acid or L-glutamate by PVN or RVLM nucleus through a rat model of continuous microinfusion and a model of myocardial ischemia-reperfusion injury.The effect of excitatory changes on myocardial ischemiareperfusion injury in rats,and the relationship between central PVN and RVLM projection was explored by neural tracing technique,and the regulatory role of PVN-RVLM pathway in myocardial ischemia-reperfusion injury in rats was preliminarily determined.Methods A microinfusion model of rat nuclei and a model of myocardial ischemiareperfusion injury were established.The study was divided into the following three parts.The first part: the role of brain area in myocardial ischemia-reperfusion injury in rats was investigated by microinfusion of GABA or L-Glu in the PVN region.Twenty-four cleangrade healthy male Sprague-Dawley rats with successful PVN brain zone were randomly divided into 4 groups: sham operation group(S group,n=6)and myocardial ischemia reperfusion group(I/R group,n=6),?-aminobutyric acid group(GABA group,n=6)and L-glutamic acid group(L-Glu group,n=6).Rat model of myocardial ischemiareperfusion injury was established by ligating the left anterior descending coronary artery for 30 min and reperfusion for 120 min.The S group was only ligated without ligation,and the other groups were myocardial ischemia for 30 min and reperfusion for 120 min.10 min before myocardial ischemia,PVN was infused into normal saline in S group and I/R group,GABA and L-Glu were infused into PVN group in GABA group and L-Glu group,respectively.Electrocardiogram(ECG),mean arterial pressure(MAP),and heart rate(HR)were recorded before myocardial ischemia 10 min(T0),myocardial ischemia(T1),ischemia 30 min(T2),and reperfusion 120 min(T3).),and calculate the heart rateblood pressure product(rate-pressure-product,RPP).At the time of T3,the rat arterial plasma was taken and the plasma cardiac troponin I(c Tn I)level was measured.Then the rats were sacrificed and the myocardial tissue was taken to determine the area of risk(AAR)myocardial infarct volume(IS).The degree of myocardial damage is expressed by IS/AAR.The expression of c-fos protein was detected by Western blot in PVN tissues of regions.The second part: The excitatory changes of neurons induced by microinfusion of GABA or L-Glu in the region of RVLM explore the role of this region in myocardial ischemiareperfusion injury in rats.The clean-grade healthy male Sprague-Dawley rats were used to perform the RVLM region pre-embedded drug delivery catheter by stereotactic method,and 24 rats with healthy postoperative survival and no post-intubation complications were obtained.Experimental grouping and detection methods and the first part Similarly,to explore the role of RVLM brain neuron excitability in myocardial ischemia-reperfusion injury in rats and its possible mechanism.The third part: through the use of retrograde neurotropic virus(Pseudorabies virus,PRV)and retrograde tracer(cholera toxin B subunit,CTb)and other neural circuit tracer tools stereotactic injection of PVN and RVLM,preliminary exploration of PVN and The nerve fiber projection link between RVLM.Results In the first part of the study,there was no significant difference in LV+RV volume and AAR volume between the groups(P>0.05).No myocardial infarction occurred in the S group,and the other 3 groups had obvious myocardial infarction.Compared with the S group,plasma c Tn I levels were elevated in the I/R group,GABA group,and L-Glu group,and c-fos protein expression was up-regulated in the PVN region(P < 0.05),and in the I/R group and the GABA group T1-3.HR,MAP and RPP were decreased in L-Glu group at T3(P < 0.05).Compared with I/R group,GA volume,IS volume,IS/AAR percentage,plasma c Tn I concentration decreased,PVN c-fos expression was down-regulated,T1,2 HR,MAP,and RPP were decreased(P < 0.05).The volume of IS,the percentage of IS/AAR,and the concentration of plasma c Tn I in L-Glu group were increased.The expression of c-fos protein in PVN regionwas up-regulated.HR,MAP and RPP were observed at T1,2(P < 0.05).In the second part of the study,there was no significant difference in LV+RV volume and AAR volume between the groups(P>0.05).No myocardial infarction occurred in the S group,and the other 3 groups hadobvious myocardial infarction.Compared with the S group,plasma c Tn I levels were elevated in the I/R group,GABA group,and L-Glu group,and c-fos protein expression was up-regulated in the PVN region(P < 0.05),and in the I/R group and the GABA group T1-3.HR,MAP and RPP were decreased in L-Glu group at T3(P < 0.05).Compared with I/R group,GABA volume,IS volume,IS/AAR percentage,plasma c Tn I concentration decreased,PVN c-fos expression was down-regulated,T1,2 HR,MAP,and RPP were decreased(P < 0.05).The volume of IS,the percentage of IS/AAR,and the concentration of plasma c Tn I in L-Glu group were increased.The expression of c-fos protein in PVN region was up-regulated.HR,MAP and RPP were observed at T1,2.Raised(P < 0.05).In the third part of the study,traces of retrograde multi-grade viral PRV and retrograde tracer CTb showed that when retrograde RVLM was injected with PRV or CTb,scattered retrogradely labeled nerves were seen in the ipsilateral PVN region.When the retrograde tracer CTb was injected into the right PVN,no retrogradely labeled neurons were seen in the RVLM region.Conclusion The changes of neuronal excitability induced by microinjection of excitatory or inhibitory neurotransmitters through pvn or rvlm nuclei participate in the central nervous system regulation mechanism of myocardial ischemia-reperfusion injury in rats: decreased excitability can attenuate myocardial I/R injury and increased excitability aggravates myocardial I/R injury. |
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