White matter injury (WMI) is a major form of brain injury in preterm infants. Its characteristic pathological features primarily involve impaired development of oligodendrocyte precursor cells and structural damage to axons, which can lead to the neurological sequelae such as motor, behavioral, and cognitive dysfunctions. Chondroitin sulfate proteoglycans (CSPGs), as the important components of extracellular matrix, can participate in neuroinflammatory response mediated by microglial cells and dynamically balance glial scar reconstruction and axon growth by regulating specific receptors and signaling pathways. This article reviews the relationship between CSPGs and WMI, as well as the mechanisms by which CSPGs inhibit axon growth, focusing on the role of multi-target regulation of CSPGs in promoting axon plasticity and functional brain recovery, thereby providing a theoretical basis for improving the prognosis of preterm infants with WMI.
Humans ; Chondroitin Sulfate Proteoglycans/physiology* ; White Matter/pathology* ; Axons/physiology* ; Infant, Premature ; Infant, Newborn ; Animals

Acute mitochondrial damage and the energy crisis following axonal injury highlight mitochondrial transport as an important target for axonal regeneration. Syntaphilin (Snph), known for its potent mitochondrial anchoring action, has emerged as a significant inhibitor of both mitochondrial transport and axonal regeneration. Therefore, investigating the molecular mechanisms that influence the expression levels of the snph gene can provide a viable strategy to regulate mitochondrial trafficking and enhance axonal regeneration. Here, we reveal the inhibitory effect of microRNA-146b (miR-146b) on the expression of the homologous zebrafish gene syntaphilin b (snphb). Through CRISPR/Cas9 and single-cell electroporation, we elucidated the positive regulatory effect of the miR-146b-snphb axis on Mauthner cell (M-cell) axon regeneration at the global and single-cell levels. Through escape response tests, we show that miR-146b-snphb signaling positively regulates functional recovery after M-cell axon injury. In addition, continuous dynamic imaging in vivo showed that reprogramming miR-146b significantly promotes axonal mitochondrial trafficking in the pre-injury and early stages of regeneration. Our study reveals an intrinsic axonal regeneration regulatory axis that promotes axonal regeneration by reprogramming mitochondrial transport and anchoring. This regulation involves noncoding RNA, and mitochondria-associated genes may provide a potential opportunity for the repair of central nervous system injury.
Animals ; Zebrafish ; MicroRNAs/genetics* ; Nerve Regeneration/physiology* ; Mitochondria/metabolism* ; Zebrafish Proteins/genetics* ; Axons/metabolism* ; Signal Transduction/physiology* ; Axonal Transport/physiology* ; Nerve Tissue Proteins/genetics*

Demyelination and remyelination play key roles in spinal cord injury (SCI), affecting the recovery of motor and sensory functions. Research in rodent models is extensive, but the study of these processes in non-human primates is limited. Therefore, our goal was to thoroughly study the histological features of demyelination and remyelination after contusion injury of the cervical spinal cord in Macaca fascicularis. In a previous study, we created an SCI model in M. fascicularis by controlling the contusion displacement. We used Eriochrome Cyanine staining, immunohistochemical analysis, and toluidine blue staining to evaluate demyelination and remyelination. The results showed demyelination ipsilateral to the injury epicenter both rostrally and caudally, the former mainly impacting sensory pathways, while the latter primarily affected motor pathways. Toluidine blue staining showed myelin loss and axonal distension at the injury site. Schwann cell-derived myelin sheaths were only found at the center, while thinner myelin sheaths from oligodendrocytes were seen at the center and surrounding areas. Our study showed that long-lasting demyelination occurs in the spinal cord of M. fascicularis after SCI, with oligodendrocytes and Schwann cells playing a significant role in myelin sheath formation at the injury site.
Animals ; Spinal Cord Injuries/physiopathology* ; Demyelinating Diseases/etiology* ; Remyelination/physiology* ; Macaca fascicularis ; Disease Models, Animal ; Myelin Sheath/pathology* ; Oligodendroglia/pathology* ; Schwann Cells/pathology* ; Female ; Spinal Cord/pathology* ; Axons/pathology*

Effective axon regeneration is essential for the successful restoration of nerve functions in patients suffering from axon injury-associated neurological diseases. Certain self-regeneration occurs in injured peripheral axonal branches of dorsal root ganglion (DRG) neurons but does not occur in their central axonal branches. By performing rat sciatic nerve or dorsal root axotomy, we determined the expression of the dysbindin domain containing 2 (DBNDD2) in the DRGs after the regenerative peripheral axon injury or the non-regenerative central axon injury, respectively, and found that DBNDD2 is down-regulated in the DRGs after peripheral axon injury but up-regulated after central axon injury. Furthermore, we found that DBNDD2 expression differs in neonatal and adult rat DRGs and is gradually increased during development. Functional analysis through DBNDD2 knockdown revealed that silencing DBNDD2 promotes the outgrowth of neurites in both neonatal and adult rat DRG neurons and stimulates robust axon regeneration in adult rats after sciatic nerve crush injury. Bioinformatic analysis data showed that transcription factor estrogen receptor 1 (ESR1) interacts with DBNDD2, exhibits a similar expression trend as DBNDD2 after axon injury, and may targets DBDNN2. These studies indicate that reduced level of DBNDD2 after peripheral axon injury and low abundance of DBNDD2 in neonates contribute to axon regeneration and thus suggest the manipulation of DBNDD2 expression as a promising therapeutic approach for improving recovery after axon damage.
Animals ; Ganglia, Spinal/metabolism* ; Nerve Regeneration/genetics* ; Rats ; Axons/metabolism* ; Sciatic Nerve/injuries* ; Rats, Sprague-Dawley ; Male

OBJECTIVE: Treating peripheral nerve injury (PNI) presents a clinical challenge due to limited axon regeneration. Strychni Semen, a traditional Chinese medicine, is clinically used for numbness and hemiplegia. However, its role in promoting functional recovery after PNI and the related mechanisms have not yet been systematically studied. METHODS: A mouse model of sciatic nerve crush (SNC) injury was established and the mice received drug treatment via intragastric gavage, followed by behavioral assessments (adhesive removal test, hot-plate test and Von Frey test). Transcriptomic analyses were performed to examine gene expression in the dorsal root ganglia (DRGs) from the third to the sixth lumbar vertebrae, so as to identify the significantly differentially expressed genes. Immunofluorescence staining was used to assess the expression levels of superior cervical ganglia neural-specific 10 protein (SCG10). The ultra-trace protein detection technique was used to evaluate changes in gene expression levels. RESULTS: Strychni Semen and its active compounds (brucine and strychnine) improved functional recovery in mice following SNC injury. Transcriptomic data indicated that Strychni Semen and its active compounds initiated transcriptional reprogramming that impacted cellular morphology and extracellular matrix remodeling in DRGs after SNC, suggesting potential roles in promoting axon regeneration. Imaging data further confirmed that Strychni Semen and its active compounds facilitated axon regrowth in SNC-injured mice. By integrating protein-protein interaction predictions, ultra-trace protein detection, and molecular docking analysis, we identified myeloperoxidase as a potentially critical factor in the axon regenerative effects conferred by Strychni Semen and its active compounds. CONCLUSION Strychni Semen and its active compounds enhance sensory function by promoting axonal regeneration after PNI. These findings establish a foundation for the future applications of Strychni Semen and highlight novel therapeutic strategies and drug targets for axon regeneration. Please cite this article as: Zhang Y, Zhao XY, Liu MT, Zhou ZC, Cheng HB, Jiang XH, Zheng YR, Chen Z. Strychni Semen and its active compounds promote axon regeneration following peripheral nerve injury by suppressing myeloperoxidase in the dorsal root ganglia. J Integr Med. 2025; 23(2): 169-181.
Animals ; Nerve Regeneration/drug effects* ; Mice ; Peripheral Nerve Injuries/physiopathology* ; Male ; Ganglia, Spinal/enzymology* ; Axons/physiology* ; Peroxidase/antagonists & inhibitors* ; Mice, Inbred C57BL ; Drugs, Chinese Herbal/pharmacology* ; Disease Models, Animal ; Strychnine/pharmacology*

Retrograde adeno-associated viruses (AAVs) are capable of infecting the axons of projection neurons and serve as a powerful tool for the anatomical and functional characterization of neural networks. However, few retrograde AAV capsids have been shown to offer access to cortical projection neurons across different species and enable the manipulation of neural function in non-human primates (NHPs). Here, we report the development of a novel retrograde AAV capsid, AAV-DJ8R, which efficiently labeled cortical projection neurons after local administration into the striatum of mice and macaques. In addition, intrastriatally injected AAV-DJ8R mediated opsin expression in the mouse motor cortex and induced robust behavioral alterations. Moreover, AAV-DJ8R markedly increased motor cortical neuron firing upon optogenetic light stimulation after viral delivery into the macaque putamen. These data demonstrate the usefulness of AAV-DJ8R as an efficient retrograde tracer for cortical projection neurons in rodents and NHPs and indicate its suitability for use in conducting functional interrogations.
Animals ; Haplorhini ; Axons ; Motor Neurons ; Interneurons ; Macaca ; Dependovirus/genetics* ; Genetic Vectors

Axon initial segment (AIS) is the most excitable subcellular domain of a neuron for action potential initiation. AISs of cortical projection neurons (PNs) receive GABAergic synaptic inputs primarily from chandelier cells (ChCs), which are believed to regulate action potential generation and modulate neuronal excitability. As individual ChCs often innervate hundreds of PNs, they may alter the activity of PN ensembles and even impact the entire neural network. During postnatal development or in response to changes in network activity, the AISs and axo-axonic synapses undergo dynamic structural and functional changes that underlie the wiring, refinement, and adaptation of cortical microcircuits. Here we briefly introduce the history of ChCs and review recent research advances employing modern genetic and molecular tools. Special attention will be attributed to the plasticity of the AIS and the ChC-PN connections, which play a pivotal role in shaping the dynamic network under both physiological and pathological conditions.
Animals ; Neuronal Plasticity/physiology* ; Cerebral Cortex/cytology* ; Axons/physiology* ; Nerve Net/physiology* ; Humans ; Synapses/physiology* ; GABAergic Neurons/physiology*

Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disorder characterized by progressive axonopathy, jointly leading to the dying back of the motor neuron, disrupting both nerve signaling and motor control. In this review, we highlight the roles of axonopathy in ALS progression, driven by the interplay of multiple factors including defective trafficking machinery, protein aggregation, and mitochondrial dysfunction. Dysfunctional intracellular transport, caused by disruptions in microtubules, molecular motors, and adaptors, has been identified as a key contributor to disease progression. Aberrant protein aggregation involving TDP-43, FUS, SOD1, and dipeptide repeat proteins further amplifies neuronal toxicity. Mitochondrial defects lead to ATP depletion, oxidative stress, and Ca²⁺ imbalance, which are regarded as key factors underlying the loss of neuromuscular junctions and axonopathy. Mitigating these defects through interventions including neurotrophic treatments offers therapeutic potential. Collaborative research efforts aim to unravel ALS complexities, opening avenues for holistic interventions that target diverse pathological mechanisms.
Humans ; Amyotrophic Lateral Sclerosis/therapy* ; Animals ; Axons/metabolism* ; Mitochondria/metabolism* ; Motor Neurons/pathology*

Differing from other subtypes of inhibitory interneuron, chandelier or axo-axonic cells form depolarizing GABAergic synapses exclusively onto the axon initial segment (AIS) of targeted pyramidal cells (PCs). However, the debate whether these AIS-GABAergic inputs produce excitation or inhibition in neuronal processing is not resolved. Using realistic NEURON modeling and electrophysiological recording of cortical layer-5 PCs, we quantitatively demonstrate that the onset-timing of AIS-GABAergic input, relative to dendritic excitatory glutamatergic inputs, determines its bi-directional regulation of the efficacy of synaptic integration and spike generation in a PC. More specifically, AIS-GABAergic inputs promote the boosting effect of voltage-activated Na⁺ channels on summed synaptic excitation when they precede glutamatergic inputs by >15 ms, while for nearly concurrent excitatory inputs, they primarily produce a shunting inhibition at the AIS. Thus, our findings offer an integrative mechanism by which AIS-targeting interneurons exert sophisticated regulation of the input-output function in targeted PCs.
Axon Initial Segment ; Axons/physiology* ; Neurons ; Synapses/physiology* ; Pyramidal Cells/physiology* ; Interneurons/physiology* ; Action Potentials/physiology*

Spinal cord injury (SCI) disrupts the structural and functional connectivity between the higher center and the spinal cord, resulting in severe motor, sensory, and autonomic dysfunction with a variety of complications. The pathophysiology of SCI is complicated and multifaceted, and thus individual treatments acting on a specific aspect or process are inadequate to elicit neuronal regeneration and functional recovery after SCI. Combinatory strategies targeting multiple aspects of SCI pathology have achieved greater beneficial effects than individual therapy alone. Although many problems and challenges remain, the encouraging outcomes that have been achieved in preclinical models offer a promising foothold for the development of novel clinical strategies to treat SCI. In this review, we characterize the mechanisms underlying axon regeneration of adult neurons and summarize recent advances in facilitating functional recovery following SCI at both the acute and chronic stages. In addition, we analyze the current status, remaining problems, and realistic challenges towards clinical translation. Finally, we consider the future of SCI treatment and provide insights into how to narrow the translational gap that currently exists between preclinical studies and clinical practice. Going forward, clinical trials should emphasize multidisciplinary conversation and cooperation to identify optimal combinatorial approaches to maximize therapeutic benefit in humans with SCI.
Humans ; Axons/pathology* ; Nerve Regeneration/physiology* ; Spinal Cord Injuries/therapy* ; Neurons/pathology* ; Recovery of Function