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*

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*

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*

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

Diabetic neuropathic pain (DNP) is the most common disabling complication of diabetes. Emerging evidence has linked the pathogenesis of DNP to the aberrant sprouting of sensory axons into the epidermal area; however, the underlying molecular events remain poorly understood. Here we found that an axon guidance molecule, Netrin-3 (Ntn-3), was expressed in the sensory neurons of mouse dorsal root ganglia (DRGs), and downregulation of Ntn-3 expression was highly correlated with the severity of DNP in a diabetic mouse model. Genetic ablation of Ntn-3 increased the intra-epidermal sprouting of sensory axons and worsened the DNP in diabetic mice. In contrast, the elevation of Ntn-3 levels in DRGs significantly inhibited the intra-epidermal axon sprouting and alleviated DNP in diabetic mice. In conclusion, our studies identified Ntn-3 as an important regulator of DNP pathogenesis by gating the aberrant sprouting of sensory axons, indicating that Ntn-3 is a potential druggable target for DNP treatment.
Mice ; Animals ; Diabetes Mellitus, Experimental/metabolism* ; Axons/physiology* ; Diabetic Neuropathies ; Sensory Receptor Cells/metabolism* ; Neuralgia/metabolism*

The axon initial segment (AIS) is a highly specialized axonal compartment where the action potential is initiated. The heterogeneity of AISs has been suggested to occur between interneurons and pyramidal neurons (PyNs), which likely contributes to their unique spiking properties. However, whether the various characteristics of AISs can be linked to specific PyN subtypes remains unknown. Here, we report that in the prelimbic cortex (PL) of the mouse, two types of PyNs with axon projections either to the contralateral PL or to the ipsilateral basal lateral amygdala, possess distinct AIS properties reflected by morphology, ion channel expression, action potential initiation, and axo-axonic synaptic inputs from chandelier cells. Furthermore, projection-specific AIS diversity is more prominent in the superficial layer than in the deep layer. Thus, our study reveals the cortical layer- and axon projection-specific heterogeneity of PyN AISs, which may endow the spiking of various PyN types with exquisite modulation.
Mice ; Animals ; Axon Initial Segment ; Synapses/physiology* ; Pyramidal Cells/physiology* ; Cerebral Cortex ; Axons/physiology*

Enhancing remyelination after injury is of utmost importance for optimizing the recovery of nerve function. While the formation of myelin by Schwann cells (SCs) is critical for the function of the peripheral nervous system, the temporal dynamics and regulatory mechanisms that control the progress of the SC lineage through myelination require further elucidation. Here, using in vitro co-culture models, gene expression profiling of laser capture-microdissected SCs at various stages of myelination, and multilevel bioinformatic analysis, we demonstrated that SCs exhibit three distinct transcriptional characteristics during myelination: the immature, promyelinating, and myelinating states. We showed that suppressor interacting 3a (Sin3A) and 16 other transcription factors and chromatin regulators play important roles in the progress of myelination. Sin3A knockdown in the sciatic nerve or specifically in SCs reduced or delayed the myelination of regenerating axons in a rat crushed sciatic nerve model, while overexpression of Sin3A greatly promoted the remyelination of axons. Further, in vitro experiments revealed that Sin3A silencing inhibited SC migration and differentiation at the promyelination stage and promoted SC proliferation at the immature stage. In addition, SC differentiation and maturation may be regulated by the Sin3A/histone deacetylase2 (HDAC2) complex functionally cooperating with Sox10, as demonstrated by rescue assays. Together, these results complement the recent genome and proteome analyses of SCs during peripheral nerve myelin formation. The results also reveal a key role of Sin3A-dependent chromatin organization in promoting myelinogenic programs and SC differentiation to control peripheral myelination and repair. These findings may inform new treatments for enhancing remyelination and nerve regeneration.
Animals ; Axons ; Chromatin/metabolism* ; Gene Expression Profiling ; Myelin Sheath/metabolism* ; Nerve Regeneration/physiology* ; Rats ; Schwann Cells/metabolism* ; Sciatic Nerve/injuries*