Rapid Antidepressant Effect Of Combined Magnetic Stimulation System On Visual Cortex And Mechanism

Part I Establishment and effectiveness evaluation of combined magnetic stimulation system antidepressant therapyBackground: Repeated transcranial magnetic stimulation(r TMS)has been considered as an effective means of combating depression in humans and depressed model animals.However,due to its low focusing performance and weak penetrating ability,r TMS is difficult to be carried out in small animal experiments and its exact molecular and neural circuitry mechanisms cannot be explored.In order to solve this technical difficulty,this study for the first time proposed a new strategy combining superparamagnetic iron oxide(SPIO)nanoparticles and magnetic field(MF)to target magnetic stimulation in the brain area,that is the combined magnetic stimulation system(c-MSS).The c-MSS treatment(c-MSST)was used to preliminarily assess the efficacy of prelimbic cortex(Pr L)of mice,a classical antidepressant brain region.Methods: Based on the magnetic effect of SPIO nanoparticles and pulsed MF,precise c-MSS treatment(c-MSST)was implemented in small animal brain area.Magnetic resonance imaging(MRI)continuously observes the state of SPIO nanoparticles under somatic conditions.In vitro model and computer simulation were used to preliminarily explore the physical mechanism.The safety of magnetic nanoparticles was detected by cell counting kit-8(CCK-8)and lactate dehydrogenase(LDH)release assay in primary cultured mouse cortex neurons.The safety of neurocyte wasdetermined in vivo by Td T-mediated d UTP nick-end labeling(TUNEL).Chronic unpredictable mild stress(CUMS)depression model mice were successfully constructed,and accurate magnetic stimulation of the left Pr Lrapid antidepressant activity in the brain region.The activation of magnetic stimulation was detected by immunohistochemical staining for immediate reaction protein c-fos.Results:(1)After 11 days of MRI observation,the nanoparticles remained stable in the target brain region.(2)In vitro model and computer simulation results showed that the local induced electric field of SPIO nanoparticles could be increased under the action of external MF,and the effects of magnetic heating and mechanical vibration were excluded.(3)The concentration gradient and time gradient of SPIO nanoparticles were designed to culture the primary cortical neurons of fetal mice.After 24 hours of SPIO nanoparticles were given to detect the CCK8 and LDH,only 625 μg/ m L of CCK8 and LDH showed cytotoxicity.No cytotoxicity was found at the lowest effective concentration(5 μg/ m L)for 48 hours.TUNEL staining of brain slices suggested the safety of local injection of SPIO nanoparticles.(4)CUMS mice were treated with c-MSS at 10 Hz for 5 days(twice daily,5 min/time)in the left Pr L,and the anti-depression effect was the best,and the abnormal molecular markers were reversed.(5)The expression of c-fos was significantly increased by immunohistochemical staining in the brain slices of healthy mice,suggesting that 10 Hz c-MSST could significantly activate theleft Pr L.Conclusion: The self-developed c-MSST strategy used in this study is safe and effective for magnetic stimulation of the left Pr L in CUMS mice.The mechanism may be that SPIO nanoparticles can increase the local induced electric field under the action of external MF,thus activating the mouse left Pr L.Part II Selective Activation of ABCA1/Apoa1 Signalling in the Primary Visual Cortex by Magnetoelectric Stimulation Rapidly Ameliorates Depression-Like Behaviours via Regulation of Synaptic PlasticityBackground: Recent studies have found that visual cortex dysfunction is involved in the pathophysiological process of MDD.Whether the self-developed c-MSS accurately targeting theprimary visual cortex(V1)can quickly improve the depressive mice and its mechanism has not been fully clarified.Methods: SPIO nanoparticles were microinjected into V1,and c-MSST magnetic intervention was realized under self-developed magnetic pulse sequence.CUMS or intritoneal injection of lipopolysaccharide(LPS)induced depression mice.The depression and anxiety related behavioral paradigm to evaluate the anti-depression efficacy of c-MSST.The isobaric tagging for relative and absolute quantification(i TRAQ)-based relative quantitative proteomics analysis was used to detect the differently expressed proteins in V1 region of each group of model mice,and bioinformatics analysis was used to screen the target proteins.Tissue specific knockdown adeno-associated virus(AAV)was constructed to target proteins,and the mechanism of effect was determined by behavioral,western blotting,golgi staining and electrophysiology.Enzyme-linked immunosorbent assay(ELISA)was used to determine the levels of candidate molecules in clinical patient and mouse plasma samples.The correlation between candidate molecules and neuropsychological data and receiver operating characteristic(ROC)curve were further analyzed.Results:This study found that(1)after 5-day intervention with 5Hz c-MSST(twice daily,5 min/time),the depression like behavior of the two models of mice was quickly corrected,and the anxiety like behavior was improved in LPS mice.(2)The results of proteomics,bioinformatics analysis and sample validation showed that c-MSST could reverse the abnormal decrease of the expression of apolipoprotein A1(Apo A1)and ATP binding cassette transporter A1(ABCA1)in V1 of CUMS mice.(3)Further construction of AAV specific knockdown neuron ABCA1 expression can increase the susceptibility to depression and synaptic plasticity in mice.C-MSST can be reversed,including reversing abnormal synaptic structure,synaptic associated protein expression and increasing long-term potentiation(LTP),and the basic synaptic transmission is significantly related to the data of scurose preference test and forced swim test.(4)ELISA showed that the plasma Apo A1 level of CUMS mice decreased significantly and could be corrected by the intervention of c-MSST in V1.The level of Apo A1 in peripheral plasma of MDD patients decreased significantly,which was negatively correlated with 24 item Hamilton Depression Scale(HAMD-24)and cognitive factor score,and had the diagnostic value of MDD.The targeted intervention of neuronavigation r TMS in visual cortex for 5 days could significantly improve the level of Apo A1 in plasma.Conclusion: The precise targeted intervention of c-MSST in V1 can quickly reverse the depression like behavior of mice,and its mechanism may be to improve the synaptic plasticity by regulating ABCA1 / Apo A1 signal in neurons.