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Evaluation of the recovery of injured optic nerves using the F-VEP wave pattern. (A) Locations of silver needle electrodes. ▲ , the reference electrode; , the recording electrode; , the ground electrode. The red color indicated the testing eye of the rat. (B) Representative F-VEP tracings 4 weeks following ONC in the sham surgery, NC-shRNA and lingo-1-shRNA groups. Y-axis scale, 25 µV; x-axis scale, 10 ms. (C) N1 amplitude 2 and 4 weeks following ONC. (D) N1 latency 2 and 4 weeks following ONC. Error bars represent standard error of the mean, n=10. * P<0.05, ** P<0.01 and *** P<0.001. Lingo-1, leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein 1; NC-shRNA, negative control shRNA; shRNA, short hairpin RNA; F-VEP, flash visual evoked potential; NS, not significant.
Source publication
Leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein 1 (lingo-1) is selectively expressed on neurons and oligodendrocytes in the central nervous system and acts as a negative regulator in neural repair, implying a potential role in optic neuropathy. The aim of the present study was to determine whether ade...
Contexts in source publication
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... inhibition of lingo-1 preserves F-VEP after ONC. F-VEPs were measured to test the functional recovery after ONC. The N1 waves were detected before, and 2 and 4 weeks post-injury (Fig. 6A). The ONC procedure lead to a delay in peak latencies of N1 waves. Both in lingo-1-shRNA and NC-shRNA group, longer N1 wave latencies were observed at 2 weeks (P<0.05) and 4 weeks post-injury compared with the respective control groups (P<0.01; Fig. 6C and D). The P1-N2 amplitudes 4 weeks post-injury in the sham, NC-shRNA and ...
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... recovery after ONC. The N1 waves were detected before, and 2 and 4 weeks post-injury (Fig. 6A). The ONC procedure lead to a delay in peak latencies of N1 waves. Both in lingo-1-shRNA and NC-shRNA group, longer N1 wave latencies were observed at 2 weeks (P<0.05) and 4 weeks post-injury compared with the respective control groups (P<0.01; Fig. 6C and D). The P1-N2 amplitudes 4 weeks post-injury in the sham, NC-shRNA and lingo-1-shRNA groups were 36.27±7.81, 5.27±3.56, 17.06±2.89 µV, respectively ( Fig. 6C; Table I). Compared with the NC-shRNA group, the lingo-1-shRNA-treated group exhibited a decreased latency of N1 waves at 2 weeks (P<0.01) and 4 weeks post-injury (P<0.001; Fig. 6D). ...
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... waves. Both in lingo-1-shRNA and NC-shRNA group, longer N1 wave latencies were observed at 2 weeks (P<0.05) and 4 weeks post-injury compared with the respective control groups (P<0.01; Fig. 6C and D). The P1-N2 amplitudes 4 weeks post-injury in the sham, NC-shRNA and lingo-1-shRNA groups were 36.27±7.81, 5.27±3.56, 17.06±2.89 µV, respectively ( Fig. 6C; Table I). Compared with the NC-shRNA group, the lingo-1-shRNA-treated group exhibited a decreased latency of N1 waves at 2 weeks (P<0.01) and 4 weeks post-injury (P<0.001; Fig. 6D). No complete restoration of N1 waves was observed in the current study. The results suggest that lingo-1-shRNA treatment can partially preserve the visual ...
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... Fig. 6C and D). The P1-N2 amplitudes 4 weeks post-injury in the sham, NC-shRNA and lingo-1-shRNA groups were 36.27±7.81, 5.27±3.56, 17.06±2.89 µV, respectively ( Fig. 6C; Table I). Compared with the NC-shRNA group, the lingo-1-shRNA-treated group exhibited a decreased latency of N1 waves at 2 weeks (P<0.01) and 4 weeks post-injury (P<0.001; Fig. 6D). No complete restoration of N1 waves was observed in the current study. The results suggest that lingo-1-shRNA treatment can partially preserve the visual function in the ONC model. Detailed data of F-VEP recording are listed in Table ...
Citations
... Lingo-1 and the Rock2 signaling pathway are involved in many degenerative CNS diseases, such as Alzheimer's disease, multiple sclerosis, and optic nerve injury. The primary pathological changes associated with Rock2 activation include neuronal death, axonal degeneration, glial hyperplasia, and demyelination (Wu et al., 2018;Hanf et al., 2020;Quan et al., 2020). However, at present, no research exists regarding the mechanism through which Lingo-1 expression is upregulated by CO-induced brain damage. ...
Many hypotheses exist regarding the mechanism underlying delayed encephalopathy after acute carbon monoxide poisoning (DEACMP), including the inflammation and immune-mediated damage hypothesis and the cellular apoptosis and direct neuronal toxicity hypothesis; however, no existing hypothesis provides a satisfactory explanation for the complex clinical processes observed in DEACMP. Leucine-rich repeat and immunoglobulin-like domain-containing protein-1 (LINGO-1) activates the Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil containing protein kinase 2 (ROCK2) signaling pathway, which negatively regulates oligodendrocyte myelination, axonal growth, and neuronal survival, causing myelin damage and participating in the pathophysiological processes associated with many central nervous system diseases. However, whether LINGO-1 is involved in DEACMP remains unclear. A DEACMP model was established in rats by allowing them to inhale 1000 ppm carbon monoxide gas for 40 minutes, followed by 3000 ppm carbon monoxide gas for an additional 20 minutes. The results showed that compared with control rats, DEACMP rats showed significantly increased water maze latency and increased protein and mRNA expression levels of LINGO-1, RhoA, and ROCK2 in the brain. Compared with normal rats, significant increases in injured neurons in the hippocampus and myelin sheath damage in the lateral geniculate body were observed in DEACMP rats. From days 1 to 21 after DEACMP, the intraperitoneal injection of retinoic acid (10 mg/kg), which can inhibit LINGO-1 expression, was able to improve the above changes observed in the DEACMP model. Therefore, the overexpression of LINGO-1 appeared to increase following carbon monoxide poisoning, activating the RhoA/ROCK2 signaling pathway, which may be an important pathophysiological mechanism underlying DEACMP. This study was reviewed and approved by the Medical Ethics Committee of Xiangya Hospital of Central South Hospital (approval No. 201612684) on December 26, 2016.
... 12,17,18 We previously reported that in an optic nerve crush (ONC) model, inhibition of LINGO-1 by RNA interference promoted regeneration of the optic nerve and the survival of RGCs. 19 Although inhibition of LINGO-1 promotes the survival of neurons and RGCs, the underlying mechanism is unclear. ...
... Optic nerve crush injury was performed as described previously. 19,24 In brief, after general anesthesia, a lateral canthotomy was performed on the temporal conjunctiva of the right eye of the rat using conjunctival scissors, the lateral rectus muscle was detached, and the optic nerve was exposed under a binocular surgical microscope. ...
... To examine the neuroprotective effects of inhibition of SP1, we As we reported previously, 19 there was considerable loss of RGCs in F I G U R E 2 Regulation of LINGO-1 by SP1 and inhibition of SP1 attenuated LINGO-1-mediated RGC death in vitro. A, RT-qPCR analysis showed that overexpression of SP1 increased LINGO-1 expression in HEK293 cells (n = 4, means ± SD compared to vector by Student's t test, ***P < .001). ...
Backgrounds
Insults to the axons in the optic nerve head are the primary cause of loss of retinal ganglion cells (RGCs) in traumatic, ischemic nerve injury or degenerative ocular diseases. The central nervous system–specific leucine‐rich repeat protein, LINGO‐1, negatively regulates axon regeneration and neuronal survival after injury. However, the upstream molecular mechanisms that regulate LINGO‐1 signaling and contribute to LINGO‐1–mediated death of RGCs are unclear.
Methods
The expression of SP1 was profiled in optic nerve crush (ONC)–injured RGCs. LINGO‐1 level was examined after SP1 overexpression by qRT‐PCR. Luciferase assay was used to examine the binding of SP1 to the promoter regions of LINGO‐1. Primary RGCs from rat retina were isolated by immunopanning and RGCs apoptosis were determined by Tunnel. SP1 and LINGO‐1 expression was investigated using immunohistochemistry and Western bolting. Neuroprotection was assessed by RGC counts, RNFL thickness, and VEP tests after inhibition of SP1 shRNA.
Results
We demonstrate that SP1 was upregulated in ONC‐injured RGCs. SP1 was bound to the LINGO‐1 promoter, which led to increased expression of LINGO‐1. Treatment with recombinant Nogo‐66 or LINGO‐1 promoted apoptosis of RGCs cultured under serum‐deprivation conditions, while silencing of SP1 promoted the survival of RGCs. SP1 and LINGO‐1 colocalized and were upregulated in ONC‐injured retinas. Silencing of SP1 in vivo reduced LINGO‐1 expression and protected the structure of RGCs from ONC‐induced injury, but there was no sign of recovery in VEP.
Conclusions
Our findings imply that SP1 regulates LINGO‐1 expression in RGCs in the injured retina and provide insight into mechanisms underlying LINGO‐1–mediated RGC death in optic nerve injury.
Progressive multiple sclerosis (PMS) is an immune-initiated neurodegenerative condition that lacks effective therapies. Although peripheral immune infiltration is a hallmark of relapsing-remitting MS (RRMS), PMS is associated with chronic, tissue-restricted inflammation and disease-associated reactive glial states. The effector functions of disease-associated microglia, astrocytes, and oligodendrocyte lineage cells are beginning to be defined, and recent studies have made significant progress in uncovering their pathologic implications. In this review, we discuss the immune-glia interactions that underlie demyelination, failed remyelination, and neurodegeneration with a focus on PMS. We highlight the common and divergent immune mechanisms by which glial cells acquire disease-associated phenotypes. Finally, we discuss recent advances that have revealed promising novel therapeutic targets for the treatment of PMS and other neurodegenerative diseases.
Successful establishment of reconnection between retinal ganglion cells and retinorecipient regions in the brain is critical to optic nerve regeneration. However, morphological assessments of retinorecipient regions are limited by the opacity of brain tissue. In this study, we used an innovative tissue cleaning technique combined with retrograde trans-synaptic viral tracing to observe changes in retinorecipient regions connected to retinal ganglion cells in mice after optic nerve injury. Specifically, we performed light-sheet imaging of whole brain tissue after a clearing process. We found that pseudorabies virus 724 (PRV724) mostly infected retinal ganglion cells, and that we could use it to retrogradely trace the retinorecipient regions in whole tissue-cleared brains. Unexpectedly, PRV724-traced neurons were more widely distributed compared with data from previous studies. We found that optic nerve injury could selectively modify projections from retinal ganglion cells in the hypothalamic paraventricular nucleus, intergeniculate leaflet, ventral lateral geniculate nucleus, central amygdala, basolateral amygdala, Edinger-Westphal nucleus, and oculomotor nucleus, but not the superior vestibular nucleus, red nucleus, locus coeruleus, gigantocellular reticular nucleus, or facial nerve nucleus. Our findings demonstrate that the tissue clearing technique, combined with retrograde trans-synaptic viral tracing, can be used to objectively and comprehensively evaluate changes in mouse retinorecipient regions that receive projections from retinal ganglion cells after optic nerve injury. Thus, our approach may be useful for future estimations of optic nerve injury and regeneration.
As the residual vision following a traumatic optic nerve injury can spontaneously recover over time, we explored the spontaneous plasticity of cortical networks during the early post-optic nerve crush (ONC) phase. Using in vivo wide-field calcium imaging on awake Thy1-GCaMP6s mice, we characterized resting state and evoked cortical activity before, during, and 31 days after ONC. The recovery of monocular visual acuity and depth perception was evaluated in parallel. Cortical responses to an LED flash decreased in the contralateral hemisphere in the primary visual cortex and in the secondary visual areas following the ONC, but was partially rescued between 3 and 5 days post-ONC, remaining stable thereafter. The connectivity between visual and non-visual regions was disorganized after the crush, as shown by a decorrelation, but correlated activity was restored 31 days after the injury. The number of surviving retinal ganglion cells dramatically dropped and remained low. At the behavioral level, the ONC resulted in visual acuity loss on the injured side and an increase in visual acuity with the non-injured eye. In conclusion, our results show a reorganization of connectivity between visual and associative cortical areas after an ONC, which is indicative of spontaneous cortical plasticity.
Purpose:
To determine alteration of dendritic spines and associated changes in the primary visual cortex (V1 region) related to unilateral optic nerve crush (ONC) in adult mice.
Methods:
Adult unilateral ONC mice were established. Retinal nerve fiber layer (RNFL) thickness was measured by spectral-domain optical coherence tomography. Visual function was estimated by flash visual evoked potentials (FVEPs). Dendritic spines were observed in the V1 region contralateral to the ONC eye by two-photon imaging in vivo. The neurons, reactive astrocytes, oligodendrocytes, and activated microglia were assessed by NeuN, glial fibrillary acidic protein, CNPase, and CD68 in immunohistochemistry, respectively. Tropomyosin receptor kinase B (TrkB) and the markers in TrkB trafficking were estimated using western blotting and co-immunoprecipitation. Transmission electron microscopy and western blotting were used to evaluate autophagy.
Results:
The amplitude and latency of FVEPs were decreased and delayed at 3 days, 1 week, 2 weeks, and 4 weeks after ONC, and RNFL thickness was decreased at 2 and 4 weeks after ONC. Dendritic spines were reduced in the V1 region contralateral to the ONC eye at 2, 3, and 4 weeks after ONC, with an unchanged number of neurons. Reactive astrocyte staining was increased at 2 and 4 weeks after ONC, but oligodendrocyte and activated microglia staining remained unchanged. TrkB was reduced with changes in the major trafficking proteins, and enhanced autophagy was observed in the V1 region contralateral to the ONC eye.
Conclusions:
Dendritic spines were reduced in the V1 region contralateral to the ONC eye in adult mice. Reactive astrocytes and decreased TrkB may be associated with the reduced dendritic spines.
As the residual vision following a traumatic optic nerve injury can spontaneously recover over time, we explored the plasticity of cortical networks during the early post-optic nerve crush (ONC) phase. Using in vivo wide-field calcium imaging on awake Thy1-GCaMP6s mice, we characterized resting state and evoked cortical activity before, during, and 30 days after ONC. The recovery of monocular visual acuity and depth perception was evaluated at the same time points. Cortical responses to an LED flash decreased in the contralateral hemisphere in the primary visual cortex and in the secondary visual areas following the ONC, but was partially rescued between 3 and 5 days post-ONC, remaining stable thereafter. The connectivity between visual and non-visual regions was disorganized after the crush, as shown by a decorrelation, but correlated activity was restored 30 days after the injury. The number of surviving retinal ganglion cells dramatically dropped and remained low. At the behavioral level, the ONC resulted in visual acuity loss on the injured side and an increase in visual acuity with the non-injured eye. In conclusion, our results show a reorganization of connectivity between visual and associative cortical areas after an ONC, which is indicative of spontaneous cortical plasticity.
