Ethanol changes Nestin-promoter induced neural stem cells to disturb newborn dendritic spine remodeling in the hippocampus of mice

Adolescent binge drinking leads to long-lasting disorders of the adult central nervous system,particularly aberrant hippocampal neurogenesis.In this study,we applied in vivo fluorescent tracing using NestinCreERT2::Rosa26-tdTomato mice and analyzed the endogenous neurogenesis lineage progression of neural stem cells(NSCs)and dendritic spine formation of newborn neurons in the subgranular zone of the dentate gyrus.We found abnormal orientation of tamoxifen-induced tdTomato+(tdTom^(+))NSCs in adult mice 2 months after treatment with EtOH(5.0 g/kg,i.p.)for 7 consecutive days.EtOH markedly inhibited tdTom^(+)NSCs activation and hippocampal neurogenesis in mouse dentate gyrus from adolescence to adulthood.EtOH(100 mM)also significantly inhibited the proliferation to 39.2%and differentiation of primary NSCs in vitro.Adult mice exposed to EtOH also exhibited marked inhibitions in dendritic spine growth and newborn neuron maturation in the dentate gyrus,which was partially reversed by voluntary running or inhibition of the mammalian target of rapamycinenhancer of zeste homolog 2 pathway.In vivo tracing revealed that EtOH induced abnormal orientation of tdTom+NSCs and spatial misposition defects of newborn neurons,thus causing the disturbance of hippocampal neurogenesis and dendritic spine remodeling in mice.

PCDH17 restricts dendritic spine morphogenesis by regulating ROCK2-dependent control of the actin cytoskeleton,modulating emotional behavior

Proper regulation of synapse formation and elimination is critical for establishing mature neuronal circuits and maintaining brain function.Synaptic abnormalities,such as defects in the density and morphology of postsynaptic dendritic spines,underlie the pathology of various neuropsychiatric disorders.Protocadherin 17(PCDH17)is associated with major mood disorders,including bipolar disorder and depression.However,the molecular mechanisms by which PCDH17 regulates spine number,morphology,and behavior remain elusive.In this study,we found that PCDH17 functions at postsynaptic sites,restricting the number and size of dendritic spines in excitatory neurons.Selective overexpression of PCDH17 in the ventral hippocampal CA1 results in spine loss and anxiety-and depression-like behaviors in mice.Mechanistically,PCDH17 interacts with actin-relevant proteins and regulates actin filament(F-actin)organization.Specifically,PCDH17 binds to ROCK2,increasing its expression and subsequently enhancing the activity of downstream targets such as LIMK1 and the phosphorylation of cofilin serine-3(Ser3).Inhibition of ROCK2 activity with belumosudil(KD025)ameliorates the defective F-actin organization and spine structure induced by PCDH17 overexpression,suggesting that ROCK2 mediates the effects of PCDH17 on F-actin content and spine development.Hence,these findings reveal a novel mechanism by which PCDH17 regulates synapse development and behavior,providing pathological insights into the neurobiological basis of mood disorders.

Dendritic spine density changes and homeostatic synaptic scaling:a meta-analysis of animal studies

Mechanisms of homeostatic plasticity promote compensatory changes of cellular excitability in response to chronic changes in the network activity.This type of plasticity is essential for the maintenance of brain circuits and is involved in the regulation of neural regeneration and the progress of neurodegenerative disorders.One of the most studied homeostatic processes is synaptic scaling,where global synaptic adjustments take place to restore the neuronal firing rate to a physiological range by the modulation of synaptic receptors,neurotransmitters,and morphology.However,despite the comprehensive literature on the electrophysiological properties of homeostatic scaling,less is known about the structural adjustments that occur in the synapses and dendritic tree.In this study,we performed a meta-analysis of articles investigating the effects of chronic network excitation(synaptic downscaling)or inhibition(synaptic upscaling)on the dendritic spine density of neurons.Our results indicate that spine density is consistently reduced after protocols that induce synaptic scaling,independent of the intervention type.Then,we discuss the implication of our findings to the current knowledge on the morphological changes induced by homeostatic plasticity.

Effects of ketamine and midazolam on morphology of dendritic spines in hippocampal CA1 region of neonatal mice

Background It is a common phenomenon that children experience multiple general anesthesias in clinical practice, which raises the question whether repeated exposure to general anesthetics would interfere with the development of the central nervous system of children. The present study was designed to evaluate the effects of repeated treatment with ketamine or midazolam on postnatal dendrite development by examining the morphology of the dendritic spines of the pyramidal neurons in the hippocampal CA1 region in mice. Methods The transgenic green fluorescent protein-M line （GFP-M） mice were used in this study. Ketamine （100 mg/kg） midazolam （50 mg/kg） or saline （10 ml/kg） was administered intraperitoneally once a day on consecutive days from postnatal day 8 （P8） to postnatal day 12 （P12）. At postnatal day 13 （P13） and postnatal day 30 （P30）, the density and length of the apical dendritic spines of the pyramidal neurons in the hippocampal CA1 region were examined under a confocal microscope. Results At P13, for both the ketamine group and the midazolam group, the dendritic spines were found with a comparatively lower density and longer average length than in the control group. At P30, no significant difference in the density or average length of dendritic spines was found between the anesthetic group and control group. Conclusions This study indicated that repeated exposure to ketamine or midazolam in neonatal mice impaired dendritic spine maturation immediately afterwards, but this influence seemed to disappear during further postnatal development.

Multiple Mild Stimulations Reduce Membrane Distribution of CX3CR1 Promoted by Annexin al in Microglia to Attenuate Excessive Dendritic Spine Pruning and Cognitive Deficits Caused by a Transient Ischemic Attack in Mice

A transient ischemic attack(TIA)can cause reversible and delayed impairment of cognition,but the specific mechanisms arestill unclear.Annexin al(ANXA1)is a phospholipid-binding protein.Here,we confirmed that cognition and hippocampal synapses were impaired in TIA-treated mice,and this could be rescued by multiple mild stimulations(MMS).TIA promoted the interaction of ANXAl and CX3CR1,increased the membrane distribution of CX3CR1 in microglila,and thus enhanced the CX3CR1 and CX3CL1 interaction.These phenomena induced by TIA could be reversed by MMS.Meanwhile,the CX3CR1 membrane distribution and CX3CR1-CX3CL1 interaction were upregulated in primary cultured microglia overexpressing ANXAl,and the spine density was significantly reduced in co-cultured microglia overexpressing ANXAl and neurons.Moreover,ANXAl overexpression in microglia abolished the protection of MMS after TIA.Collectively,our study provides a potential strategy for treating the delayed synaptic injury caused by TIA.

MiR-130a regulates and dendritic spine MeCP2 neurite outgrowth density by targeting

MicroRNAs （miRNAs） are critical for both development and function of the central nervous system. Significant evidence suggests that abnormal expression of miRNAs is associated with neurodevelopmental disorders. MeCP2 protein is an epigenetic regulator repressing or activating gene transcription by binding to methylated DNA. Both loss-of-function and gain-of-function muta- tions in the MECP2 gene lead to neurodevelopmental disorders such as Rett syndrome, autism and MECP2 duplication syndrome. In this study, we demonstrate that miR-130a inhibits neurite outgrowth and reduces dendritic spine density as well as dendritic complexity. Bioinformatics analyses, cell cultures and biochemical experiments indicate that miR-130a targets MECP2 and down-regulates MeCP2 protein expression. Further- more, expression of the wild-type MeCP2, but not a loss- of-function mutant, rescues the miR-130a-induced phe- notype. Our study uncovers the MECP2 gene as a pre- vious unknown target for miR-130a, supporting that miR-130a may play a role in neurodevelopment by reg- ulating MeCP2. Together with data from other groups,our work suggests that a feedback regulatory mecha- nism involving both miR-130a and MeCP2 may serve to ensure their appropriate expression and function in neural development.

Effects of reproductive experience on paternal behavior,levels of testosterone,prolactin in serum and dendritic spines in medial prefrontal cortex of mandarin voles

Maternal behaviors and brains change dramatically with pregnancy,parturition and other mothering experiences.However,whether paternal behavior,brain plasticity and levels of relevant hormones also change along with fathering experience and pups’age remains unclear.Using socially monogamous mandarin voles(Micro-tus mandarinus),we found that experienced fathers exhibited more active paternal behaviors,such as licking,retrievals and nest building,but less paternal care,such as huddling,than new fathers.The high levels of licking and nest building appeared in the earlier days of their mate’s lactation.Experienced fathers retrieved 9–13-day-old pups more frequently.However,these paternal behaviors did not show significant changes with age of pups in new fathers.In addition,experienced fathers had dramatically higher prolactin levels than new fathers but had similar concentrations of testosterone to new fathers.New fathers had lower levels of testosterone but higher levels of prolactin than new paired males.The fathers had higher prolactin levels in the earlier days of their mate’s lactation.The new and experienced fathers had similar dendritic length and spine density on pyramidal neurons in the medial prefrontal cortex but displayed higher levels than new paired males.Taken together,these results indicate that reduction of testosterone levels and increase of prolactin levels may be associated with initiation of paternal care.Fathering experience significantly affects levels of parental care and paternal behaviors toward different aged pups,and brain plasticity can also be enhanced by transition to fatherhood.

Epigenetic regulation of neuronal dendrite and dendritic spine development

Dendrites and the dendritic spines of neurons play key roles in the connectivity of the brain and have been recognized as the locus of long-term synaptic plasticity,which is correlated with learning and memory.The development of dendrites and spines in the mammalian central nervous system is a complex process that requires specific molecular events over a period of time.It has been shown that specific molecules are needed not only at the spine’s point of contact,but also at a distance,providing signals that initiate a cascade of events leading to synapse formation.The specific molecules that act to signal neuronal differentiation,dendritic morphology,and synaptogenesis are tightly regulated by genetic and epigenetic programs.It has been shown that the dendritic spine structure and distribution are altered in many diseases,including many forms of mental retardation(MR),and can also be potentiated by neuronal activities and an enriched environment.Because dendritic spine pathologies are found in many types of MR,it has been proposed that an inability to form normal spines leads to the cognitive and motor deficits that are characteristic of MR.Epigenetic mechanisms,including DNA methylation,chromatin remodeling,and the noncoding RNA-mediated process,have profound regulatory roles in mammalian gene expression.The study of epigenetics focuses on cellular effects that result in a heritable pattern of gene expression without changes to genomic encoding.Despite extensive efforts to understand the molecular regulation of dendrite and spine development,epigenetic mechanisms have only recently been considered.In this review,we will focus on epigenetic mechanisms that regulate the development and maturation of dendrites and spines.We will discuss how epigenetic alterations could result in spine abnormalities that lead to MR,such as is seen in fragile X and Rett syndromes.We will also discuss both general methodology and recent technological advances in the study of neuronal dendrites and spines.

c-Abl kinase at the crossroads of healthy synaptic remodeling and synaptic dysfunction in neurodegenerative diseases

Our ability to learn and remember depends on the active formation,remodeling,and elimination of synapses.Thus,the development and growth of synapses as well as their weakening and elimination are essential for neuronal rewiring.The structural reorganization of synaptic complexes,changes in actin cytos keleton and organelle dynamics,as well as modulation of gene expression,determine synaptic plasticity.It has been proposed that dys regulation of these key synaptic homeostatic processes underlies the synaptic dysfunction observed in many neurodegenerative diseases.Much is known about downstream signaling of activated N-methyl-D-aspartate andα-amino-3-hydroxy-5-methyl-4-isoazolepro pionate receptors;howeve r,other signaling pathways can also contribute to synaptic plasticity and long-lasting changes in learning and memory.The non-receptor tyrosine kinase c-Abl(ABL1)is a key signal transducer of intra and extracellular signals,and it shuttles between the cyto plasm and the nucleus.This review focuses on c-Abl and its synaptic and neuronal functions.Here,we discuss the evidence showing that the activation of c-Abl can be detrimental to neurons,promoting the development of neurodegenerative diseases.Nevertheless,c-Abl activity seems to be in a pivotal balance between healthy synaptic plasticity,regulating dendritic spines remodeling and gene expression after cognitive training,and synaptic dysfunction and loss in neurodegenerative diseases.Thus,c-Abl genetic ablation not only improves learning and memory and modulates the brain genetic program of trained mice,but its absence provides dendritic spines resiliency against damage.Therefo re,the present review has been designed to elu cidate the common links between c-Abl regulation of structural changes that involve the actin cytos keleton and organelles dynamics,and the transc riptional program activated during synaptic plasticity.By summarizing the recent discove ries on c-Abl functions,we aim to provide an overview of how its inhibition co uld be a potentially fruitful treatment to improve degenerative outcomes and delay memory loss.

Neurotrophic fragments as therapeutic alternatives to ameliorate brain aging

Aging is a global phenomenon and a complex biological process of all living beings that introduces various changes.During this physiological process,the brain is the most affected organ due to changes in its structural and chemical functions,such as changes in plasticity and decrease in the number,diameter,length,and branching of dendrites and dendritic spines.Likewise,it presents a great reduction in volume resulting from the contraction of the gray matter.Consequently,aging can affect not only cognitive functions,including learning and memory,but also the quality of life of older people.As a result of the phenomena,various molecules with notable neuroprotective capacity have been proposed,which provide a therapeutic alternative for people under conditions of aging or some neurodegenerative diseases.It is important to indicate that in recent years the use of molecules with neurotrophic activity has shown interesting results when evaluated in in vivo models.This review aims to describe the neurotrophic potential of molecules such as resveratrol(3,5,4′-trihydroxystilbene),neurotrophins(brain-derived neurotrophic factor),and neurotrophic-type compounds such as the terminal carboxyl domain of the heavy chain of tetanus toxin,cerebrolysin,neuropeptide-12,and rapamycin.Most of these molecules have been evaluated by our research group.Studies suggest that these molecules exert an important therapeutic potential,restoring brain function in aging conditions or models of neurodegenerative diseases.Hence,our interest is in describing the current scientific evidence that supports the therapeutic potential of these molecules with active neurotrophic.

Blunt dopamine transmission due to decreased GDNF in the PFC evokes cognitive impairment in Parkinson’s disease

Studies have found that the absence of glial cell line-derived neurotrophic factor may be the primary risk factor for Parkinson’s disease. However, there have not been any studies conducted on the potential relationship between glial cell line-derived neurotrophic factor and cognitive performance in Parkinson’s disease. We first performed a retrospective case-control study at the Affiliated Hospital of Xuzhou Medical University between September 2018 and January 2020 and found that a decreased serum level of glial cell line-derived neurotrophic factor was a risk factor for cognitive disorders in patients with Parkinson’s disease. We then established a mouse model of Parkinson’s disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and analyzed the potential relationships among glial cell line-derived neurotrophic factor in the prefrontal cortex, dopamine transmission, and cognitive function. Our results showed that decreased glial cell line-derived neurotrophic factor in the prefrontal cortex weakened dopamine release and transmission by upregulating the presynaptic membrane expression of the dopamine transporter, which led to the loss and primitivization of dendritic spines of pyramidal neurons and cognitive impairment. In addition, magnetic resonance imaging data showed that the long-term lack of glial cell line-derived neurotrophic factor reduced the connectivity between the prefrontal cortex and other brain regions, and exogenous glial cell line-derived neurotrophic factor significantly improved this connectivity. These findings suggested that decreased glial cell line-derived neurotrophic factor in the prefrontal cortex leads to neuroplastic degeneration at the level of synaptic connections and circuits, which results in cognitive impairment in patients with Parkinson’s disease.

Microglia and astrocytes mediate synapse engulfment in a MER tyrosine kinase-dependent manner after traumatic brain injury

Recent studies have shown that microglia/macrophages and astrocytes can mediate synaptic phagocytosis through the MER proto-oncokinase in developmental or stroke models,but it is unclear whether the same mechanism is also active in traumatic brain injury.In this study,we established a mouse model of traumatic brain injury and found that both microglia/macrophages and astrocytes phagocytosed synapses and expression of the MER proto-oncokinase increased 14 days after injury.Specific knockout of MER in microglia/macrophages or astrocytes markedly reduced injury volume and greatly improved neurobehavioral function.In addition,in both microglia/macrophages-specific and astrocytes-specific MER knock-out mice,the number of microglia/macrophage and astrocyte phagocytosing synapses was markedly decreased,and the total number of dendritic spines was increased.Our study suggested that MER proto-oncokinase expression in microglia/macrophages and astrocytes may play an important role in synaptic phagocytosis,and inhibiting this process could be a new strategy for treating traumatic brain injury.

Fasting produces antidepressant-like effects via activating mammalian target of rapamycin complex 1 signaling pathway in ovariectomized mice

Recent studies have shown that a 9-hour fast in mice reduces the amount of time spent immobile in the forced swimming test.Howeve r,whether 9-hour fasting has therapeutic effects in female mice with depressive symptoms has not been established.Therefore,in this study,we simulated perimenopausal depression via an ovariectomy in mice,and subjected them to a single 9-hour fasting 7 days later.We found that the ovariectomy increased the time spent immobile in the forced swimming test,inhibited expression of the mammalian target of rapamycin complex 1 signaling pathway in the hippocampus and prefro ntal cortex,and decreased the density of dendritic spines in the hippocampus.The 9-hour acute fasting alleviated the above-mentioned phenomena.Furthermore,all of the antidepressant-like effects of 9-hour fasting were reve rsed by an inhibitor of the mammalian to rget of rapamycin complex 1.Electrophysiology data showed a remarkable increase in long-term potentiation in the hippocampal CA1 of the ovariectomized mice subjected to fasting compared with the findings in the ovariectomized mice not subjected to fasting.These findings show that the antidepressant-like effects of 9-hour fasting may be related to the activation of the mammalian target of the rapamycin complex 1 signaling pathway and synaptic plasticity in the mammalian hippocampus.Thus,fasting may be a potential treatment for depression.

Initiation of dendritic NMDA spikes co-regulated via distance-dependent and dynamic distribution of the spine number and morphology in neuron dendrites

Dendritic spines are small membranous protrusions that receive synaptic inputs from other neurons,enabling the initiation of dendritic N-methyl-D-aspartic(NMDA)spikes and somatic action potentials.During learning and memory processes,both the number of spines on a dendrite and the morphology of individual spines are constantly changing.The individual influence of spine number and morphology on dendritic NMDA spikes has already been revealed,but the functional significance of the coregulation of spine number and morphology on NMDA spikes remains elusive.Here,we systematically investigated the initiation of local dendritic NMDA spikes by the dynamic distributions of the spine number and morphology on single dendrites in reconstructed neuron models.Different from the traditional cognition,we found the threshold number of spines required to generate local dendrite NMDA spikes on distal dendrites is fewer than that on proximal ones,because the thinner distal dendrites own higher impedance.As for the spine morphology,the presence of moreα-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid(AMPA)receptors on the spine leads to larger NMDA spikes rather than an increase in the spine dimension alone.Furthermore,we first suggested that a single dendrite containing spines with gradually increasing head diameters away from the soma could generate larger NMDA spikes than that irrational distribution of spine morphology containing spines with decreasing head diameters,which can be compensated by the increasing spine number.Complementarily,the distance-dependent distribution of spine number and morphology co-regulate the intension of dendritic NMDA spikes.These findings about the threshold for NMDA spikes provide novel insights into the role of the irrational dynamic distribution of the spine number and morphology in senescence and disease processes such as Alzheimer’s disease,schizophrenia,and Parkinson’s disease,which causes abnormal neuron firing.

Synaptic aging disrupts synaptic morphology and function in cerebellar Purkinje cells

Synapses are key structures in neural networks,and are involved in learning and memory in the central nervous system.Investigating synaptogenesis and synaptic aging is important in understanding neural development and neural degeneration in diseases such as Alzheimer disease and Parkinson’s disease.Our previous study found that synaptogenesis and synaptic maturation were harmonized with brain development and maturation.However,synaptic damage and loss in the aging cerebellum are not well understood.This study was designed to investigate the occurrence of synaptic aging in the cerebellum by observing the ultrastructural changes of dendritic spines and synapses in cerebellar Purkinje cells of aging mice.Immunocytochemistry,Di I diolistic assays,and transmission electron microscopy were used to visualize the morphological characteristics of synaptic buttons,dendritic spines and synapses of Purkinje cells in mice at various ages.With synaptic aging in the cerebellum,dendritic spines and synaptic buttons were lost,and the synaptic ultrastructure was altered,including a reduction in the number of synaptic vesicles and mitochondria in presynaptic termini and smaller thin specialized zones in pre-and post-synaptic membranes.These findings confirm that synaptic morphology and function is disrupted in aging synapses,which may be an important pathological cause of neurodegenerative diseases.

Homer signaling pathways as effective therapeutic targets for ischemic and traumatic brain injuries and retinal lesions

Ischemic and traumatic insults to the central nervous system account for most serious acute and fatal brain injuries and are usually characterized by primary and secondary damage.Secondary damage presents the greatest challenge for medical staff;however,there are currently few effective therapeutic targets for secondary damage.Homer proteins are postsynaptic scaffolding proteins that have been implicated in ischemic and traumatic insults to the central nervous system.Homer signaling can exert either positive or negative effects during such insults,depending on the specific subtype of Homer protein.Homer 1b/c couples with other proteins to form postsynaptic densities,which form the basis of synaptic transmission,while Homer 1a expression can be induced by harmful external factors.Homer 1c is used as a unique biomarker to reveal alterations in synaptic connectivity before and during the early stages of apoptosis in retinal ganglion cells,mediated or affected by extracellular or intracellular signaling or cytoskeletal processes.This review summarizes the structural features,related signaling pathways,and diverse roles of Homer proteins in physiological and pathological processes.Upregulating Homer 1a or downregulating Homer 1b/c may play a neuroprotective role in secondary brain injuries.Homer also plays an important role in the formation of photoreceptor synapses.These findings confirm the neuroprotective effects of Homer,and support the future design of therapeutic drug targets or gene therapies for ischemic and traumatic brain injuries and retinal disorders based on Homer proteins.

(＋)-Borneol is neuroprotective against permanent cerebral ischemia in rats by suppressing production of proinflammatory cytokines

Stroke is one of the leading causes of disability and death globally.It occurs when a major artery is occluded in the brain and leads to death of cells within the injured tissue.（＋）-Borneol,a simple bicyclic monoterpene extracted from traditional Chinese medicine,is widely used in various types of diseases.However,no study has proved the effects of（＋）-borneol on functional recovery from permanent ischemic stroke and the mechanism is still unknown.Here,we report that in the rat model of permanent cerebral ischemia,we found that（＋）-borneol（1.0 mg/kg） significantly ameliorated infarct size and neurological scores via reducing the expression of inducible nitric oxide synthase（iNOS）and tumor necrosis factor-alpha（TNF-α） in a dose dependent manner.Notably,（＋）-borneol showed long-term effects on the improvement of sensorimotor functions in the photothrombotic model of stroke,which decreased the number of foot faults in the grid-walking task and forelimb asymmetry scores in the cylinder task,at least in part through reducing loss of dendritic spines in the length,brunch number and density.These findings suggest that（＋）-borneol could serve as a therapeutic target for ischemic stroke.

Activities of nicotinic acetylcholine receptors modulate neurotransmission and synaptic architecture

The cholinergic system is involved in a broad spectrum of brain function, and its failure has been implicated in Alzheimer＇s disease. Acetylcholine transduces signals through muscarinic and nicotinic acetylcholine receptors, both of which influence synaptic plasticity and cognition. However, the mechanisms that relate the rapid gating of nicotinic acetylcholine receptors to persistent changes in brain function have remained elusive. Recent evidence indicates that nicotinic acetylcholine receptors activities affect synaptic morphology and density, which result in persistent rearrangements of neural connectivity. Further investigations of the relationships between nicotinic acetylcholine receptors and rearrangements of neural circuitry in the central nervous system may help understand the pathogenesis of Alzheimer＇s disease.

Influence of environmental enrichment on hippocampal synapses in adolescent offspring of mothers exposed to prenatal stress

Environmental enrichment attenuates hippocampal synaptic injury induced by prenatal stress in offspring. However, the influence of hippocampal synaptic changes and regional differences in prenatal stress remains poorly understood. The present study induced stress in Sprague Dawley rats, which were at gestational age 13-19 days. Following weaning, the offspring were raised in an enriched environment to establish models of stress ＋ enriched environment. Dendritic spine density and synaptophysin expression were detected in hippocampal neurons using Golgi staining and western blot analysis, respectively. Results showed that enriched environment increased dendritic spine density of apical dendrites in CA1 pyramidal cells and basal dendrites of granular cells in the outer layer of the dentate gyrus. In addition, hippocampal synaptophysin expression increased and the effects of prenatal stress on neuronal dendritic spines were reversed in adolescence.

Time-lapse changes of in vivo injured neuronal substructures in the central nervous system after low energy two-photon nanosurgery

There is currently very little research regarding the dynamics of the subcellular degenerative events that occur in the central nervous system in response to injury. To date, multi-photon excitation has been primarily used for imaging applications; however, it has been recently used to selectively disrupt neural structures in living animals. However, understanding the complicated processes and the essential underlying molecular pathways involved in these dynamic events is necessary for studying the underlying process that promotes neuronal regeneration. In this study, we introduced a novel method allowing in vivo use of low energy（less than 30 m W） two-photon nanosurgery to selectively disrupt individual dendrites, axons, and dendritic spines in the murine brain and spinal cord to accurately monitor the time-lapse changes in the injured neuronal structures. Individual axons, dendrites, and dendritic spines in the brain and spinal cord were successfully ablated and in vivo imaging revealed the time-lapse alterations in these structures in response to the two-photon nanosurgery induced lesion. The energy（less than 30 m W） used in this study was very low and caused no observable additional damage in the neuronal sub-structures that occur frequently, especially in dendritic spines, with current commonly used methods using high energy levels. In addition, our approach includes the option of monitoring the time-varying dynamics to control the degree of lesion. The method presented here may be used to provide new insight into the growth of axons and dendrites in response to acute injury.