Objective:To investigate the neural regulatory mechanism of parvalbumin-positive interneurons(PV-INs)in the dentate gyrus(DG)involved in the impairment of spatial recognition memory by exercise-induced chronic fatigue.Methods:Male Sprague-Dawley(SD)rats were divided into control group and fatigue group by random num-ber method.A three-level incremental load treadmill training program was selected to establish a chronic exhaustion exercise fatigue model.The spatial recognition memory ability of rats was tested by novel object recognition test.The ac-tivation levels and quantitative changes of astrocytes(AS)and PV-INs in the DG region was observed and quantified through immunofluorescence staining and immunohistochemical staining.The phosphorylation level of calcium/calmodu-lin-dependent protein kinase Ⅱ(CaMK Ⅱ)in the hippocampus was detected by Western blot.Results:In the test of novel object recognition,the exploration time of novel object was reduced in the fatigue group,and the discrimination index was significantly lower than that in the control group(P＜0.01).Immunohistochemical staining showed that PV-INs in the DG region of fatigue rats were lighter and fewer than those in the control group,the fibers were short and sparse,and the positive cell density and average optical density of cells were significantly lower than those in the control group(P＜0.01).Immunofluorescence staining showed that AS was significantly activated,glial fibrillary acidic pro-tein(GFAP)was stained deeply,and the cell processes were dense and elongated in the DG region of fatigue rats.The positive cell density and mean fluorescence intensity were significantly higher than those of the control group(P＜0.01).The results of Western blot showed that the phosphorylation level of CaMK Ⅱ protein in the hippocampus of the fatigue group was significantly reduced than that of the control group(P＜0.01).Conclusion:Exercise-induced chro-nic fatigue inhibited PV-INs in the rat hippocampal DG region.The excessive activation of AS following exercise fatigue may be a major contributor to this PV-INs suppression.Concurrently,reduced phosphorylation levels of CaMK Ⅱ protein were observed in hippocampal tissue.These alterations ultimately impaired spatial recognition memory in the rats.

Objective:To investigate the protective effect of PSD95 on neurobehavioral abnormalities and synaptic damage in cortex induced by hypoxia exposure in mice.Methods:The 3-week-old C57BL/6 male mice were injected with neuron-specific adeno-associated virus through stereotaxic brain after 7 days of normal environment adaptation.The mice were divided into normoxia group(AAV-NC-Nor),control hypoxia group(AAV-NC-Hyp),normal oxygen group with over-expression of postsynaptic density-95(PSD95)(AAV-PSD95-Nor),and hypoxia group with over-expression of PSD95(AAV-PSD95-Hyp).Using a hypobaric hypoxia chamber,PSD95-overexpressing mice were continuously ex-posed to hypoxic conditions for 14 days to establish a hypoxia exposure model.The open field,elevated cross maze and conditioned fear tests were used to detect the neurobehavioral activities of mice,and Golgi staining was used to observe the density of neuronal dendritic spines in cortex.The expression of PSD95,SYN1 and N-methyl-D-aspartate receptor subtype 2A(NMDAR2A)were detected by Western blot.Result:Compared with the normal oxygen group,the total distance and average speed of exercise in the open field experiment of mice in hypoxia group increased(P＜0.01),the rigidity time of mice in the conditioned fear box decreased(P＜0.01),and the density of dendritic spines in cortical region decreased(P＜0.05).The expressions of PSD95,SYN1 and NMDAR2A were decreased(P＜0.05).After the over-expression of PSD95,the autonomic activity of mice was reduced,the fear memory was relieved(P＜0.05),the dendrite density was reversed(P＜0.05),and the expression of synaptic related protein was increased(P＜0.05).Conclusion:Over-expression of PSD95 can alleviate neurobehavioral abnormalities and decline of fear memory induced under hypoxia exposure,protect neuronal dendritic spine injury in cortical region,and up-regulate the expression of syn-aptic protein.

Objective:This study aims to investigate the effects on the behavior of mice by optogenetic activation the neural projections from the central amygdala(CeA)to the dorsal raphe nucleus(DRN).Methods:AAV-hSyn-eYFP virus was injected into CeA of C57BL/6J mice,and the projections from CeA to DRN were observed by immunofluores-cent staining.The AAV-hSyn-ChR2-mCherry virus was injected into CeA,and AAV-DIO-eYFP was injected into DRN in Ser-Cre mouse to specifically label the serotonergic neurons.Patch-clamp recording combined with optogenetic tech-nology were employed to record the light-evoked inward currents of DRN serotonergic neurons.AAV-hSyn-ChR2-mCher-ry virus was injected into CeA and optical fiber was implanted into DRN,and the effects of optogenetic activation of the CeA-DRN neural circuit on the locomotor ability of mice was studied by open field test.Results:Four weeks after injec-tion of AAV-hSyn-eYFP virus into CeA of C57BL/6J mice,axon terminals from CeA eYFP-cells were observed in the DRN.Activation of the neural projections from the CeA to the DRN induced inhibitory inward currents in DRN seroton-ergic neurons.Activation of the projections from CeA to DRN circuit decreased the total distance and the time of the center of the open field in mice,and increased the immobility time of mice.Conclusion:The CeA neurons directly pro-ject to the DRN.Activation of CeA-DRN circuit exerts an inhibitory regulatory effect on DRN serotonergic neurons and reduces the locomotor ability of mice.

Objective:Vascular cell adhesion molecule 1(VCAM1)is involved in a series of physiological and pathological processes,such as immune and inflammatory response,tumor cell metastasis and invasion.But under trau-matic brain injury(TBI),specific types of cells with VC AM1 expression and the related functions are not clear.In order to further explore the specific functions of VCAM1 involved in TBI,this study constructed reporter mice of VCAM1 to explore the response of VCAM1 to TBI in detail.Methods:VCAM1-Cre/ERT2::Ai14 reporter mice were constructed by gene targeting technology and Cre/loxP system,the labeled cell types and labeling efficiency were validated by im-munofluorescence staining and reporter mice hybridization.The stab wound model was used to simulate TBI to induce the changes of VCAM1 expression in cells,and the characteristics of VCAM1 positive astrocytes were detected by immu-nofluorescence staining and fluorescent probe labeling.Results:The labeling efficiency of VCAM1-Cre/ERT2::Ai14 re-porter mice was higher than that of VCAM1 antibody as was seen by labeling of more endothelial cells of blood vessels and unique astrocytes.The distribution of these astrocytes was specific,for example in the nucleus accumbens,amygda-la,hypothalamus,and paraventricular fiber systems.TBI could significantly induce the expression of VCAM1 in astro-cytes(P＜0.0001).These induced astrocytes developed reactive qualities,including somal hypertrophy,GFAP ex-pression and proliferative ability.Conclusion:VCAM1-Cre/ERT2::Ai14 reporter mice could label cells with VCAM1 expression more sensitively,so they were more effective tools for observing expression and function of VCAM1.The up-regulation of VCAM1 expression in astrocytes after TBI surgery suggested that VCAM1 was an inflammatory response molecule in astrocytes,we recommended it as a new molecular indicator of reactive astrocytes.

Objective:To investigate the electrophysiological characteristics of medium spiny neurons(MSNs)expressing D1 or D2 dopamine receptors in the striatum of mice,providing a theoretical basis for exploring their roles in motor disorders,reward,and anxiety-depression.Methods:Six male adult D1-tdTomato and D2-tdTomato mice were used.After anesthesia and decapitation,the brains were quickly removed,and coronal slices were prepared.Whole-cell patch recording were employed to record spontaneous firing,resting membrane potential,and action potential parameters of D1 and D2 MSNs in the striatum.Comparative analyses were conducted to identify differences between the two types of neurons.Results:The frequency of spontaneous excitatory postsynaptic currents(sEPSCs)in D1-MSNs was signifi-cantly lower than that in D2-MSNs(P＜0.001),but there was no difference in amplitude;whereas no significant differences were observed in the frequency or amplitude of spontaneous inhibitory postsynaptic currents(sIPSCs)between D1-MSNs and D2-MSNs.Compared with D1-MSNs,D2-MSNs had a lower resting membrane potential(P＜0.01),a significantly lower rheobase for action potential generation(P＜0.01),and the frequency of action potentials induced by depolarizing current injection was significantly higher in D2-MSNs(P＜0.001).Following perfusion with dopamine(60 μmol/L),the frequency of action potentials in D1-MSNs significantly increased(P＜0.001),while the frequency of action potentials in D2-MSNs significantly decreased(P＜0.001).Conclusion:There are significant differences in the electrophysiological properties between D1-MSNs and D2-MSNs in the striatum of mice.

Objective:To evaluate the effect of deep brain stimulation(DBS)of the lateral cerebellar nucleus(LCN)on synaptic plasticity in a traumatic brain injury(TBI)rat model of the medial prefrontal cortex(mPFC).Methods:A controllable mPFC injury rat model was prepared using a hydraulic impact method.Two weeks after inju-ry,stimulation electrodes were implanted into the left LCN.Electrical stimulation was initiated at the 4th week after injury and continued for 30 days.The learning and memory function of the rats was evaluated using the Morris water maze.RT-qPCR and Western blot were used to detect the mRNA and protein expressions of brain-derived neurotrophic factor(BDNF),postsynaptic density protein 95(PSD95),and growth-associated protein 43(GAP43)in the mPFC region.Results:The learning and memory function of the mPFC-injured rats significantly decreased.The expressions of BDNF,PSD95,and GAP43 in mPFC decreased.DBS treatment significantly enhanced the learning and memory ability of mPFC-injured rats,and simultaneously upregulated the expressions of BDNF,PSD95,and GAP43 in mPFC.Conclusion:LCN DBS is an effective method for treating cognitive impairment caused by TBI,and it may achieve this through activating the neural plasticity mechanism of the mPFC.

Objective:To investigate the role and underlying mechanism of parthanatos death in neonatal SD rats with bilirubin encephalopathy(BE).Methods:Eighty 3-day-old neonatal SD rats were selected and randomly divided into control group and BE group.The BE model was established by intraperitoneal injection of bilirubin solution,and the pathological changes in the hippocampus were observed by hematoxylin-eosin(HE)staining and Nissl staining.The protein expressions of the phosphorylation of the core histone protein H2AX(termed gamma H2AX),poly ADP-ribose polymerasw-1(PARP-1)and apoptosis-inducing factor(AIF)in hippocampus were detected by Western blot.Immuno-fluorescence staining was used to detect the expression and distribution of AIF in hippocampus.Results:Compared with the control group,neonatal SD rats developed jaundice 12 hours after bilirubin injection,accompanied by slow weight gain.HE staining and Nissl staining showed that the hippocampus in BE group were damaged and the content of Nissl bodies was decreased.Western blot results showed that the expression of γ-H2AX protein in hippocampus began to increase at 72 h after modeling(P＜0.05),and the levels of PARP-1 and AIF protein in hippocampus increased signif-icantly at 72 h after modeling(P＜0.05).Immunofluorescence staining showed increased AIF expression and nuclear translocation.Conclusion:Intraperitoneal injection of bilirubin can induce DNA damage in hippocampal neurons of neonatal SD rats and activate the PARP-1/AIF pathway to cause parthanatos death of hippocampal neurons.

Objective:To investigate the effects and mechanisms of subchronic exposure to pyrethrin on the mice nervous system.Methods:Twenty-four male mice were randomly divided into a control group,low-,medium-,and high-dose groups,and were exposed continuously for 28 days.The control group received corn oil.The general condi-tion of the mice was observed,and the body weight and brain organ coefficient were measured.Neurobehavioral tests were conducted after the exposure period.The histopathological changes of the hippocampus in mice were observed by HE and nissl staining.The activities of lactate dehydrogenase(LDH),superoxide dismutase(SOD),catalase(CAT)and the contents of malondialdehyde(MDA),glutathione(GSH),acetylcholine(ACh)and glutamate(Glu)in brain tissue of mice were detected by biochemical kit.The Western blot was employed to measure the expression levels of kelch-like ech-associated protein 1(Keap1),nuclearfactorerythroid2-relatedfactor2(Nrf2),and heme oxygenase 1(HO-1)in brain tissue of mice.Results:Compared with the control group,the body weight of the mice in the high-dose group decreased,the brain organ coefficient increased,and the neurological function test showed that the mice had reduced autonomic activity,delayed nerve reflex,and impaired sensory and motor function.Histopathology showed that the hippocampal neurons in the middle-and high-dose groups presented with pyknosis,vacuolization,and disordered arrangement of the CA3 area.Biochemical analysis indicated that in the brain tissue of mice,the activity of LDH and the content of MDA were increased in the medium-and high-dose groups,while the activity of CAT and the content of GSH were decreased.The content of Glu was increased and the content of ACh was decreased.The activity of SOD was reduced in the low-,medium-,and high-dose groups.Western blot analysis showed that the expression of HO-1 and Nrf2 protein in the brain tissue of mice in the middle-and high-dose groups was down-regulated,while the expression of Keap1 protein in the high-dose group was up-regulated.Conclusion:Pyrethrin may cause damage to the nervous system by affecting the Keap1/Nrf2/HO-1 signaling pathway and neurotransmitter levels.

Objective:To evaluate the role and molecular mechanism of laminin β1(LAMB1)in cortical neurons in regulation of glutamate receptors.Methods:Recombinant lentivirus(LV-shLamb1)-mediated knockdown of LAMB1 expression in mouse primary cortical neurons was performed,followed by immunofluorescence staining and Western blot to detect changes in F-actin,glutamate receptor subtypes(AMPA receptors GluR1/GluR2,NMDA receptors NR1/NR2A),and ERK-related protein expression in cortical neurons.Results:LV-shLamb1 significantly inhibited LAMB1 expression in mouse cortical neurons.Concurrently,LV-shLamb1 markedly increased F-actin polymerization,as well as the expression of AMPA receptor subunits GluR1 and GluR2,and NMDA receptor subunits NR1 and NR2A.Further,Western blot detection showed that the phosphorylation level of ERK was significantly increased after LV-shLamb1 infec-tion.Conclusion:LAMB1 is expressed in cortical neurons.Suppression of LAMB1 expression in mouse cortical neu-rons activates the ERK pathway,which in turn promotes the polymerization of the cytoskeletal protein F-actin and the expression of glutamate receptors.This suggests that LAMB1 may regulate F-actin homeostasis and glutamate receptor levels through the ERK pathway,thereby playing a potentially important role in neuronal function.

Objective:To analyze the differentially expressed genes and related functional pathways of mouse sciatic nerves of Schwann cells(SCs)in early in vitro Wallerian degeneration(WD).Methods:The sciatic nerves of adult male C57BL/6J mice were Wallerian degeneration in vitro,and total RNA was extracted and transcriptome sequencing was performed at 3 h and 6 h after degeneration,respectively.The differentially expressed genes(DEGs),gene ontology(GO)and Kyoto encyclopedia of genes and genomes(KEGG)pathway enrichment were analyzed by bioinformatics.Results:Compared with the Control group,3961 and 5538 DEGs were screened in the WD 3 h group(WD3h)and the 6 h group(WD6h)of in vitro,respectively.The most significantly up-regulated genes mainly included molecules related to inflammation and immunity and neurotrophic factors.GO analysis showed that DEGs in both groups were enriched in positive transcriptional regulation and metabolic processes.KEGG pathway enrichment analysis revealed that DEGs were mainly concentrated in TNF signaling pathway,MAPK signaling pathway and ribosome production.Conclusion:At the early stage of WD,SCs up-regulates the genes related to inflammation and immunity to promote the progression of WD and secrete neurotrophic factors to support the survival of neurons,accompanied by the activation of TNF signaling path-way and MAPK signaling pathway.