Retinal Ganglion Cell Density Research Articles

NLRX1 limits inflammatory neurodegeneration in the anterior visual pathway

Chronic innate immune activation in the central nervous system (CNS) significantly contributes to neurodegeneration in progressive multiple sclerosis (MS). Using multiple experimental autoimmune encephalomyelitis (EAE) models, we discovered that NLRX1 protects neurons in the anterior visual pathway from inflammatory neurodegeneration. We quantified retinal ganglion cell (RGC) density and optic nerve axonal degeneration, gliosis, and T-cell infiltration in Nlrx1−/− and wild-type (WT) EAE mice and found increased RGC loss and axonal injury in Nlrx1−/− mice compared to WT mice in both active immunization EAE and spontaneous opticospinal encephalomyelitis (OSE) models. To minimize the effects of Nlrx1−/− on peripheral lymphocyte priming during EAE, we performed adoptive transfer experiments, in which activated myelin-specific T cells were transferred into lymphocyte-deficient Rag−/− or Nlrx1−/−Rag−/− mice. In this model, we found more severe microgliosis and astrogliosis in the optic nerve of Nlrx1−/−Rag−/− mice compared to Rag−/− mice, suggesting a regulatory role of NLRX1 in innate immune cells. Transcriptome analysis in primary astrocytes activated with LPS and IFNγ demonstrated that NLRX1 suppresses NF-κB activation and regulates mitochondrial oxidative phosphorylation in inflammatory reactive astrocytes. The novel pharmacologic NLRX1 activators NX-13 and LABP-66 decreased LPS-mediated gene expression of inflammatory cytokines and chemokines in mixed glial cultures. Moreover, treating EAE mice with oral LABP-66, compared to vehicle, after the onset of paralysis resulted in less anterior visual pathway neurodegeneration. These data suggest that pharmacologic NLRX1 activators have the potential to limit inflammatory neurodegeneration. This study highlights that NLRX1 could serve as a promising target for neuroprotection in progressive MS and other neurodegenerative diseases. Further studies are needed to better understand the cell-specific mechanisms underlying the neuroprotective role of NLRX1 in response to inflammation in the CNS.

Curcumin nanoparticles: Neuroprotection in Alzheimer's disease assessed through the eye

Aims/Purpose: Alzheimer's disease (AD) is the most prevalent form of dementia and remains a pressing concern in our society with an ageing population. Increasing evidences suggest a link between brain damage and retinal ganglion cell (RGC) loss opening new paradigm to diagnose this condition using the eye as a window to the brain. Curcumin is a natural polyphenol with neuroprotective properties but a low bioavailability preventing its use as a potential treatment in AD. The goal of this research was to assess a novel formulation of curcumin in a triple transgenic Alzheimer's disease (3xTg‐AD) mouse model and to demonstrate a correlation between Aβ/pTau brain deposition and RGC loss.Methods: 10‐month‐old 3xTg‐AD mice were treated for 3 months with either 0.38 mg/kg intranasal curcumin nanoparticles (CNs) (n = 7) or the equivalent vehicle (n = 6). After 3 months of treatment, animals were imaged using Detection of Apoptosing Retinal Cells (DARC). DARC count was defined as the number of fluorescent spots counted by a masked investigator. After sacrifice, their brains were harvested and immunostained for amyloid‐beta (Aβ) and phosphorylated tau (pTau). Retinas were immunostained with Brn3a, a retinal ganglion cell (RGC) marker. Then, RGC regularity index (RI) was calculated because it is more sensitive than RGC density and declining values of RI are observed during RGC loss and correlate with disease severity.Results: In the brain, CNs were able to reduce Aβ deposition (2.9 ± 0.3 vs 4.4 ± 0.4 Aβ score, p < 0.05) and pTau deposition (1.9 ± 0.7 vs 6.3 ± 1.5 pTau deposition, p < 0.05) compared to the equivalent vehicle. DARC count was reduced with CN treatment compared to vehicle (17.4 ± 3.3 vs 49.1 ± 13.3 DARC spots, p < 0.05). More importantly, CN treatment increased significantly RGC RI compared to vehicle (1.73 ± 0.04 vs 1.58 ± 0.04, p < 0.05) suggesting a neuroprotective effect by reducing RGC loss. Interestingly, DARC count correlated with RGC RI (correlation coefficient ‐0.452, p < 0.05) and Aβ deposition in the brain (correlation coefficient 0.509, p < 0.05).Conclusions: CNs are neuroprotective by reducing Aβ and pTau deposition in the brain and RGC loss. More importantly, DARC can be used to monitor disease activity as it correlates with RGC loss and Aβ deposition in the brain. Further studies are needed to confirm these results.

PTau pathology in the retina of TAU58 mice: association with ganglion cell degeneration and implications on seeding and propagation of pTau from human brain lysates

The accumulation of abnormal phosphorylated Tau protein (pTau) in neurons of the brain is a pathological hallmark of Alzheimer’s disease (AD). PTau pathology also occurs in the retina of AD cases. Accordingly, questions arise whether retinal pTau can act as a potential seed for inducing cerebral pTau pathology and whether retinal pTau pathology causes degeneration of retinal neurons. To address these questions, we (1) characterized pTau pathology in the retina of TAU58 mice, (2) determined the impact of pTau pathology on retinal ganglion cell density, and (3) used this mouse model to test whether brain lysates from AD and/or non-AD control cases induce seeding in the retina and/or propagation into the brain. TAU58 mice developed retinal pTau pathology at 6 months of age, increasing in severity and extent with age. TAU58 mice showed reduced retinal ganglion cell density compared to wild-type mice, which declined with age and pTau pathology progression. Brain lysates from non-AD Braak neurofibrillary tangle (NFT) stage I controls increased retinal pTau pathology after subretinal injection compared to phosphate-buffered saline (PBS) but did not accelerate pTau pathology in the brain. In contrast, subretinally injected AD brain lysates accelerated pTau pathology in the retina and the contralateral superior colliculus. Subretinal injection of AD brain lysates, but not of non-AD brain, induced in this context a neuroinflammatory response in the retina and in the contralateral primary visual cortex. These results lead to the following conclusions: (1) Brain lysates from AD and non-AD sources can accelerate tauopathy within the retina. (2) The anterograde propagation of pTau pathology from the retina to the brain can be triggered by subretinal injections of AD brain lysates. (3) Such subretinal injections also provoke a neuroinflammatory response in both the retina and the visual cortex. (4) The accumulation of retinal pTau is associated with the degeneration of the involved ganglion cells, indicating that retinal tauopathy might contribute to vision impairment in the elderly and underscore the retina’s potential role in spreading tau pathology to the brain.

Morphological and functional observations of a novel model of retinal ischemia injury induced by bilateral carotid artery stenosis in mice.

To investigate the features of retinal ischemic injuries in a novel mouse model with bilateral carotid artery stenosis (BCAS). BCAS was induced with microcoil implantation in 6-8-week-old C57BL6 mice. Cerebral blood flow was monitored at 2, 7, and 28d postoperatively. Retinal morphological changes were evaluated by fundus photography and hematoxylin-eosin staining. Fluorescein fundus angiography (FFA) was performed to detect retinal vascular changes and circulation. The levels of apoptosis, activation of neurogliosis, and expression of hypoxia-inducible factor (HIF)-1α in the retina were assessed by Western blotting and immunofluorescence staining, followed by retinal ganglion cell (RGC) density detection. Additionally, electrophysiological examinations including photopic negative response (PhNR) was also performed. The mice demonstrated an initial rapid decrease in cerebral blood flow, followed by a 4-week recovery period after BCAS. The ratio of retinal artery and vein was decreased under fundus photography and FFA. Compared with the sham mice, BCAS mice showed thinner retinal thickness on day 28. Additionally, apoptosis was increased and RGC density was decreased mainly in peripheral retinal region. Neurogliosis was mainly located in the inner retinal layers, with a stable increase in HIF-1α expression. The dark-adapted electroretinogram showed a notable reduction in the a-, b-, and oscillatory potential (OP) wave amplitudes between days 2 and 7; this gradually recovered over the following 4wk. However, the b- and OP-wave amplitudes were still significantly decreased on PhNR examination on day 28. BCAS can result in relatively mild retinal ischemia injuries in mice, mainly in the inner layer and peripheral region. Our study provides a novel animal model for investigating retinal ischemic diseases.

Systemic Hypothermia in the Acute Management of Traumatic Optic Neuropathy in a Murine Animal Model.

To examine the effects of systemic hypothermia on retinal ganglion cell survival and visual outcomes after optic nerve trauma in a sonication-inducted traumatic optic neuropathy murine animal model. Twenty mice underwent sonication-inducted traumatic optic neuropathy. Afterward, 10 mice were placed on a warming pad set to 36°C, and 10 mice were placed on a table. General anesthesia was maintained for 3 hours with subcutaneous injections of ketamine. The rectal temperature was measured every 15 minutes. Pattern electroretinograms were obtained at 2, 4, and 6 weeks. Mice were sacrificed at 6 weeks, and retinal ganglion cell counts were performed. The hypothermia group had an average rectal temperature of 23.1°C; the control group was 33.3°C. At 6 weeks, the hypothermia group had larger a-wave amplitudes (18.19 µV) than the control group (12.75 µV) (p < 0.05). At 6 weeks, retinal ganglion cell density over the entire retina was significantly higher in the hypothermia group versus the control (p < 0.0001). The hypothermia treatment group had significantly higher retinal ganglion cell density and pattern electroretinogram a-wave amplitudes 6 weeks after injury than the control group. Systemic hypothermia may have a neuroprotective effect when initiated immediately after sonication-inducted traumatic optic neuropathy.

Neuroprotective effect of Sigma-2 modulator CT2074 in a mouse model of ocular hypertension

Ocular neurodegenerative diseases, particularly glaucoma, represent a significant global cause of blindness, with current therapies inadequately addressing the degeneration of the retina and optic nerve. Recent research has identified the sigma-2 receptors as a potential druggable target to offer neuroprotection in managing ocular neurodegenerative disorders. This study investigates the neuroprotective potential of CT2074, a sigma-2 receptor modulator, in a mouse model of primary open-angle glaucoma. Male mice were subjected to unilateral magnetic bead-induced elevation of intraocular pressure (IOP) and received daily oral administration of CT2074, commencing three days prior to ocular hypertension (OHT) induction, and continuing for three weeks. Mice received bilateral intraocular injections of cholera toxin B-488 (CTB) to assess retinal ganglion cell (RGC) anterograde transport. Retina, optic nerve, and brain tissues were collected three weeks post OHT induction for quantification of RGC and axon number, with contralateral retinas and cerebelli preserved for assessment of drug exposure. CT2074 was observed in the retina at levels exceeding the 95% receptor occupancy concentration. RGC quantification showed a significant reduction in the Vehicle group compared to Naïve and CT2074 groups. Notably, the CT2074 treatment group exhibited significantly higher RGC density than the Vehicle (p<0.0001) and was no different than Naïve. Analysis of RGC axons in optic nerve cross-sections revealed significant axonal loss in both the Vehicle and CT2074 groups compared to Naïve, though the CT2074-treated group had significantly higher axon number compared to the Vehicle. Anterograde transport in the Vehicle and CT2074 groups did not differ. This study underscores the potential of CT2074 administered orally to protect RGCs exposed to elevated IOP, as evidenced by substantial preservation of RGCs and their axons compared to Vehicle-treated mice. These findings signify a promising avenue for the development of sigma-2 receptor-targeted therapeutics in glaucoma and related neurodegenerative diseases, addressing a critical unmet need in the field of ocular neuroprotection.

The influence of polyacrylamide gel substrate elasticity on primary cultures of rat retinal ganglion cells

In vitro primary cell culture models of retinal ganglion cells (RGC) are widely used to study pathomechanisms of diseases such as glaucoma. The biomechanic interaction with the culture substrate is known to influence core cellular functions. RGC cultures, however, are usually grown on rigid plastic or glass substrates. We hypothesized that soft polyacrylamide gel substrates may alter survival and neurite outgrowth of primary cultured RGC. Primary retinal cultures from postnatal (day 1-6) Wistar rats were grown on glass coverslips or polyacrylamide (PA) gel substrate with different Young's elastic moduli (0.75, 10 or 30kPa). Substrates were coated with Poly-l-lysine and/or laminin. RGC were immunostained with anti-beta-III-tubulin. Total neurite length, growth cone morphology, RGC density, mitochondrial morphology and transport as well as pro-survival pathways (Erk1/2, Akt, CREB) were assessed. PA gel substrates of E=10kPa significantly increased the total neurite length by factor 1.5 compared to glass (p=0.02). The growth cone area was significantly larger by factor 5.3 on 30kPa gels (p=0.01). The presence of a substrate coating was more important for neurite outgrowth and RGC survival on PA gels (poly-l-lysine>laminin) than on glass. Neither mitochondrial morphology and motility nor the activation of pro-survival pathways significantly differed between the four substrates. PA gel substrates significantly enhanced RGC neurite outgrowth. The signaling cascades mediating this effect remain to be determined.

Lycium barbarum glycopeptide promotes neuroprotection in ET-1 mediated retinal ganglion cell degeneration

BackgroundVascular dysregulation is one of the major risk factors of glaucoma, and endothelin-1 (ET-1) may have a role in the pathogenesis of vascular-related glaucoma. Fruit extract from Lycium Barbarum (LB) exhibits anti-ageing and multitarget mechanisms in protecting retinal ganglion cells (RGC) in various animal models. To investigate the therapeutic efficacy of LB glycoproteins (LbGP) in ET-1 induced RGC degeneration, LbGP was applied under pre- and posttreatment conditions to an ET-1 mouse model. Retina structural and functional outcomes were characterised using clinical-based techniques.MethodsAdult C57BL/6 mice were randomly allocated into four experimental groups, namely vehicle control (n = 9), LbGP-Pretreatment (n = 8), LbGP-Posttreatment (day 1) (n = 8) and LbGP-Posttreatment (day 5) (n = 7). Oral administration of LbGP 1 mg/Kg or PBS for vehicle control was given once daily. Pre- and posttreatment (day 1 or 5) were commenced at 1 week before and 1 or 5 days after intravitreal injections, respectively, and were continued until postinjection day 28. Effects of treatment on retinal structure and functions were evaluated using optical coherence tomography (OCT), doppler OCT and electroretinogram measurements at baseline, post-injection days 10 and 28. RGC survival was evaluated by using RBPMS immunostaining on retinal wholemounts.ResultsET-1 injection in vehicle control induced transient reductions in arterial flow and retinal functions, leading to significant RNFL thinning and RGC loss at day 28. Although ET-1 induced a transient loss in blood flow or retinal functions in all LbGP groups, LbGP treatments facilitated better restoration of retinal flow and retinal functions as compared with the vehicle control. Also, all three LbGP treatment groups (i.e. pre- and posttreatments from days 1 or 5) significantly preserved thRNFL thickness and RGC densities. No significant difference in protective effects was observed among the three LbGP treatment groups.ConclusionLbGP demonstrated neuroprotective effects in a mouse model of ET-1 induced RGC degeneration, with treatment applied either as a pretreatment, immediate or delayed posttreatment. LbGP treatment promoted a better restoration of retinal blood flow, and protected the RNFL, RGC density and retinal functions. This study showed the translational potential of LB as complementary treatment for glaucoma management.

Construction of glaucoma model and comparing eyeball enlargement with myopia in Guinea pig

This study aimed to develop and evaluate a guinea pig model for glaucoma, comparing resultant eyeball enlargement with an existing myopia model. Thirty guinea pigs underwent intracameral injection of magnetic microspheres to induce chronic ocular hypertension (COH). Intraocular pressure (IOP) was systematically monitored, revealing a successful induction of COH in 73.33% of the guinea pigs. The mean IOP increased from a baseline of 18.04±1.33mmHg, reaching a peak at week 3 (36.31±6.13mmHg) and remaining elevated for at least 7 weeks. All data are presented as mean±standard deviation of the mean. Subsequently, detailed assessments were conducted to validate the established glaucoma model. Immunofluorescent staining demonstrated a significant decrease in the density of retinal ganglion cells (RGC) in the glaucoma group. Optic disc excavation and notable thinning of the lamina cribrosa (LC) were observed. The quantity of optic nerve ax·ons in glaucoma group gradually decreased from baseline (44553±3608/mm2) to week 4 (28687±2071/mm2) and week 8 (17977±3697/mm2). Moreover, regarding the global enlargement of eyeballs, both the transverse and longitudinal axis in glaucomatous eyes were found to be significantly larger than that in myopic eyes, particularly in the anterior chamber depth (1.758±0.113mm vs. 1.151±0.046mm). These findings indicate distinct patterns of structural changes associated with glaucoma and myopia in the guinea pig model. This guinea pig model holds promise for future research aimed at exploring biomechanical mechanisms, therapeutic interventions, and advancing our understanding of the relationship between glaucoma and myopia.

Retinal Ganglion Cell Content Underlying Standard Automated Perimetry Size I to V Visual Sensitivities in the Non-Human Primate Experimental Glaucoma Model.

To determine the relationship between visual sensitivities from white-on-white Goldmann size I to V stimuli and the underlying retinal ganglion cell (RGC) content in the non-human primate (NHP) experimental glaucoma model. Normative data were collected from 13 NHPs. Unilateral experimental glaucoma was induced in seven animals with the least variable fields who were monitored using optical coherence tomography and 30-2 full-threshold standard automated perimetry (SAP). At varying endpoints, animals were euthanized followed by perfusion fixation, and 1-mm retinal punches were obtained from 34 corresponding SAP locations. RGCs were immunolabeled with an antibody against an RNA-binding protein (RBPMS) marker and imaged using confocal microscopy. RGC counts from each location were then related to visual sensitivities for each stimulus size, after accounting for ocular magnification. At the endpoint, the circumpapillary retinal nerve fiber layer thickness for experimental glaucoma eyes ranged from 47 to 113µm. RGC density in control eyes was greatest for the 4.24° sample (18,024 ± 6869 cells/mm2) and decreased with eccentricity. Visual sensitivity at each tested location followed that predicted by spatial summation, with the critical area increasing with eccentricity (slope = 0.0036, R2 = 0.44). The relationship between RGC counts and visual sensitivity was described using a two-line fit, where the intercept of the first segment and hinge points were dependent on eccentricity. In NHPs, SAP visual thresholds are related to the underlying RGCs. The resulting spatial summation based structure-function model can be used to estimate RGC content from any standard white-on-white stimulus size.

The correlation of caspase-3 expression with retinal ganglion and photoreceptor cell densities in diabetic retinopathy

The correlation of caspase-3 expression with retinal ganglion and photoreceptor cell densities in diabetic retinopathy

Convolutional neural networks develop major organizational principles of early visual cortex when enhanced with retinal sampling.

Primate visual cortex exhibits key organizational principles: cortical magnification, eccentricity-dependent receptive field size and spatial frequency tuning as well as radial bias. We provide compelling evidence that these principles arise from the interplay of the non-uniform distribution of retinal ganglion cells, and a quasi-uniform convergence rate from the retina to the cortex. We show that convolutional neural networks outfitted with a retinal sampling layer, which resamples images according to retinal ganglion cell density, develop these organizational principles. Surprisingly, our results indicate that radial bias is spatial-frequency dependent and only manifests for high spatial frequencies. For low spatial frequencies, the bias shifts towards orthogonal orientations. These findings introduce a novel hypothesis about the origin of radial bias. Quasi-uniform convergence limits the range of spatial frequencies (in retinal space) that can be resolved, while retinal sampling determines the spatial frequency content throughout the retina.

TRPV4 antagonist suppresses retinal ganglion cell apoptosis by regulating the activation of CaMKII and TNF-α expression in a chronic ocular hypertension rat model

Glaucoma is characterized by a progressive loss of retinal ganglion cells (RGCs), leading to irreversible visual function impairment. Sustained increase in intraocular pressure represents a major risk factor for glaucoma, yet the underlying mechanisms of RGC apoptosis induced by intraocular pressure remains unclear. This study aims to investigate the role of TRPV4 in RGC apoptosis in a rat model of chronic ocular hypertension (COH) and the underlying molecular mechanism. In the COH rat models, we evaluated the visual function, retinal pathological changes and RGC apoptosis. TRPV4 expression and downstream signaling molecules were also detected. We found that RGC density decreased and RGC apoptosis was induced in COH eyes compared with control eyes. TRPV4 expression increased significantly in response to elevated IOP. TRPV4 inhibition by the TRPV4 antagonist HC-067047 (HC-067) suppressed RGC apoptosis and protected visual function. HC-067 treatment upregulated the phosphorylation of CaMKII in both control and COH eyes. Finally, HC-067 treatment suppressed the production of TNF-α induced by ocular hypertension. The TRPV4 antagonist HC-067 might suppress RGC apoptosis by regulating the activation of CaMKII and inhibiting the production of TNF-α in the COH model. This indicated that TRPV4 antagonists may be a potential and novel therapeutic strategy for glaucoma.

COENZYME Q10 EFFECT ON NMDA RECEPTOR EXPRESSION AND RETINAL GANGLION CELL DENSITY (Experimental Study in Traumatic Optic Neuropathy Model of Wistar Rat)

Abstract&#x0D; Introduction &amp; Objectives : Traumatic optic neuropathy is a visual disturbance condition after acute injury to optic nerve. This injury results in retinal ganglion cells ischemic leading to excitotoxicity and apoptosis. Coenzyme Q10 (CoQ10) is an antioxidant and cofactor in electron transport within mitochondria that inhibits glutamate excitotoxicity and thereby preventing retinal ganglion cell apoptosis. This research aims to prove the effect of coenzyme Q10 on NMDA receptor expression and retinal ganglion cell density in rat model of traumatic optic neuropathy.&#x0D; Methods : This study use post-test only randomized controlled groups design. Traumatic optic neuropathy wistar rats model was made by optic nerve crushed method, then given oral CoQ10 100mg/kgBW after 1 hour for 14 days in treatment group. Retinal histopathological specimen was made with immunohistochemistry and Haematoxyllin-eosin staining and examined under microscope with 400x magnification. Data was verified and statistically analyzed.&#x0D; Results : The NMDA receptor expression in the treatment group was significantly lower than control (p=0.009). The retinal ganglion cell density in the treatment group was significantly higher than control (p=0.009). There was a significant correlation between NMDA receptor expression and retinal ganglion cell density in the treatment group (p = 0.012) with a strong negative correlation direction (r = - 0.652).&#x0D; Conclusion : Administration of CoQ10 in traumatic optic neuropathy model rats affects NMDA receptor expression and retinal ganglion cell density. NMDA receptor expression was lower with higher retinal ganglion cell density in the treatment group. NMDA receptor expression was inversely proportional to retinal ganglion cell density in the treatment group.

EFFECT OF TOPICAL BRIMONIDINE ON NMDA RECEPTOR EXPRESSION AND RETINA GANGLION CELL DENSITY IN TRAUMATIC OPTIC NEUROPATHY RATS MODEL

Abstract&#x0D; Introduction &amp; Objectives : Traumatic optic neuropathy is a visual disturbance caused by acute injury to the optic nerve which results in retinal ganglion cell apoptosis through the glutamate excitotoxicity pathway. Brimonidine is an alpha 2-receptor agonist that acts as a neuroprotector in the glutamate excitotoxicity pathway and causes modulation of NMDA receptors associated with glutamate. Objective of this study is to prove the effect of topical brimonidine on NMDA receptor expression and retinal ganglion cell density in a rat model of traumatic optic neuropathy&#x0D; Methods : Rat models of traumatic optic neuropathy was carried out using the optic nerve crush method. The treatment group was given topical brimonidine 0.15% 1 drop/12 hours for 14 days. NMDA receptor expression was assessed by immunohistochemical staining and retinal ganglion cell density was assessed by Hematoxylin-eosin staining. Statistical analysis was performed to assess the correlation between NMDA receptor expression and retinal ganglion cell density&#x0D; Results : The Allred score of NMDA receptors expression in the treatment group was lower than control group, with significant difference (p=0.002). The mean density of retinal ganglion cells in the treatment and control group was 20,99  7,76 and 12,51  3,10, respectively with a significant difference (p=0.032). There was a significant correlation between NMDA receptor expression and retinal ganglion cell density in the treatment group (p=0.035) with strong negative correlation (r= -0.611)&#x0D; Conclusion : Topical administration of brimonidine to the Wistar rat model of traumatic optic neuropathy can suppress NMDA receptor expression and maintain retinal cell ganglion density

EFFECT OF ORAL CURCUMIN ADMINISTRATION ON NMDA RECEPTOR EXPRESSION AND RETINAL GANGLION CELL DENSITY

Abstract&#x0D; Introduction &amp; Objectives : To prove the effect of oral curcumin on NMDA receptor expression and retinal ganglion cell density.&#x0D; Methods : Wistar rats model of traumatic optic neuropathy were divided into 2 groups. The treatment group was given oral curcumin 150mg/kgBW/24 hours for 14 days 1 hour after trauma. NMDA receptor expression was examined by IHC staining and retinal ganglion cell density was examined by HE staining. Data were collected and analyzed.&#x0D; Results : NMDA expression was found to be significantly lower in the treatment group compared to the control group (p = 0.046). The mean of ganglion density in the control and treatment group was 12.88 ± 2.44 and 17.92 ± 6.95, respectively. The treatment group had a significantly higher ganglion density (p = 0.043). There was a significant relationship between NMDA receptor expression and retinal ganglion density (p = 0.043, r = -0.591).&#x0D; Conclusion : Curcumin can suppress the expression of NMDA receptors to maintain retinal ganglion density in rat models of optic neuropathy

Transsynaptic Degeneration of Retinal Ganglion Cells Following Lesions to Primary Visual Cortex in Marmosets.

A lesion to primary visual cortex (V1) in primates can produce retrograde transneuronal degeneration in the dorsal lateral geniculate nucleus (LGN) and retina. We investigated the effect of age at time of lesion on LGN volume and retinal ganglion cell (RGC) density in marmoset monkeys. Retinas and LGNs were obtained about 2years after a unilateral left-sided V1 lesion as infants (n = 7) or young adult (n = 1). Antibodies against RBPMS were used to label all RGCs, and antibodies against CaMKII or GABAA receptors were used to label nonmidget RGCs. Cell densities were compared in the left and right hemiretina of each eye. The LGNs were stained with the nuclear marker NeuN or for Nissl substance. In three animals lesioned within the first 2 postnatal weeks, the proportion of RGCs lost within 5mm of the fovea was ∼twofold higher than after lesions at 4 or 6 weeks. There was negligible loss in the animal lesioned at 2years of age. A positive correlation between RGC loss and LGN volume reduction was evident. No loss of CaMKII-positive or GABAA receptor-positive RGCs was apparent within 2mm of the fovea in any of the retinas investigated. Susceptibility of marmoset RGCs to transneuronal degeneration is high at birth and declines over the first 6 postnatal weeks. High survival rates of CaMKII and GABAA receptor-positive RGCs implies that widefield and parasol cells are less affected by neonatal cortical lesions than are midget-pathway cells.

Retinal ganglion cell and microvascular density loss in hereditary spastic paraplegia.

Hereditary spastic paraplegia (HSP) is characterized by progressive degeneration of distal axons in the long corticospinal tracts. Loss of retinal cells and microvascular networks has neither been suspected nor investigated. We concurrently examined the retinal microvasculature and retinal layer morphology in patients with HSP to assess whether retinal features may portray disease and its progression. Fifteen patients with HSP and 30 healthy controls were included in this cross-sectional case-control study. Disease severity was assessed with the Spastic Paraplegia Rating Scale (SPRS). Severity of ataxia was determined by the Scale for the Assessment and Rating of Ataxia (SARA). Retinal microvasculature was measured by means of optical coherence tomography angiography (OCT-A) and morphology of retinal layers using structural OCT. Mixed-effects models were applied for data analysis. HSP patients showed significantly reduced vessel density of the superficial vascular plexus (SVP), reduced ganglion cell layer (GCL) volume, reduced inner plexiform layer (IPL) volume and reduced temporal-inferior peripapillary retinal nerve fiber layer (pRNFL) thickness versus healthy controls. GCL volume reduction correlated significantly with the worsening of visual acuity and higher SARA scores. These findings demonstrate that, in HSP both cells and vascular networks of the retina are compromised. Assessment of the retinal GCL, IPL and SVP may aid in diagnosis and monitoring of disease progression as well as provide novel structural outcome measures for clinical trials.

Retinal microglia and ganglion cells in a cuprizone (CPZ) induced mouse model of multiple sclerosis (MS)

Aims/Purpose: Up to 90% of MS patients have ocular manifestations. Activated microglia (mg) are associated with age and diseases like MS. Mg change their activation states (ramified, hyper‐ramified, activated, amoeboid and rod) in response to stimuli, to exert either neuro‐protective or ‐toxic effects, leading to the rescue or loss of neurons. Here, we characterize retinal ganglion cell (RGC) densities and retinal mg morphotype proportions in eyes of a CPZ induced MS model and age‐matched controls.Methods: Male C57 mice were fed CPZ (0.2%w/w) mixed chow for 4 months (m) until sacrificed at 6 m (6mCPZ) or 28 m (28mCPZ) old. Age‐matched controls (6mCtrl; 28mCtrl) were fed normal chow. Enucleated eyes were fixed in 4% PFA. Whole retinas were dissected, stained (RBPMS+RGCs; iba‐1+mg), mounted and imaged. A published retinal mg morphotyping algorithm and an automated RBPMS counting script were used. Two‐way ANOVA with paired analysis (PA) was used (mg n: 6mCtrl = 15; 6mCPZ = 7; 28mCtrl = 7; 28mCPZ = 10; and RGC n: 6mCtrl = 4; 6mCPZ = 3; 28mCtrl = 3; 28mCPZ = 4).Results: There was a main effect of age for activated (p = 0.0282) and rod (p &lt; 0.0001), and disease state for rod (p = 0.04) mg. PA showed higher activated mg in 28mCtrl versus 6mCtrl (p = 0.0485), and lower rod mg in 28mCtrl versus 6mCtrl (p = 0.0374) and in 28mCPZ versus 6mCPZ (p = 0.0007). There was a main effect of age (p = 0.0001) and disease state (p = 0.04) on RBPMS density. PA showed lower RGC density in 28mCtrl versus 6mCtrl (p = 0.0025) and in 28mCPZ versus 6mCPZ (p = 0.025).Conclusions: Our results show that there is age‐related loss of rod mg and RGCs in healthy and CPZ groups, supporting reports that rod mg are involved in protecting less damaged neurons. Age‐related increased activated mg may cause RGC loss as transcription factors like TNFα, bind to RGC receptors, inducing apoptosis. Further transcriptomic analysis may clarify functional interpretations.

Protective effect of baicalin on oxidative stress injury in retinal ganglion cells through the JAK/STAT signaling pathway in vitro and in vivo.

The damage or apoptosis of retinal ganglion cells (RGCs) is one of the leading causes of various blinding eye diseases, such as glaucoma, diabetic retinopathy, optic neuritis, and ischemic optic neuropathy. Oxidative stress is involved in RGCs death. Baicalin, a flavonoid compound extracted from Scutellaria baicalensis, has various beneficial effects, including anti-inflammatory, anti-apoptotic, and antioxidant properties. However, the effects of baicalin on RGCs and the underlying mechanisms require further investigation. In this study, a glutamate-induced oxidative stress damage model of R28 cells and a rat retinal injury model were established to investigate the effects of baicalin on oxidative stress damage to RGCs and try to elucidate the underlying mechanism. In vitro experiments demonstrated that the survival rate of R28 cells after glutamate treatment dropped to 33.4%, while 10μM baicalin significantly inhibited glutamate-induced damage in RGCs (P < 0.001) and enhanced cell viability through decreasing ROS levels, increasing antioxidant enzyme activity, and suppressing the expression of inflammatory factors iNOS, TNF-α, IL-6, and IL-1β (P < 0.001). In vivo, baicalin effectively mitigated structural damage to retinal tissue and RGCs morphology induced by glutamate, increasing the thickness of the retinal ganglion cell layer, improving RGCs density, and reducing overall retinal thinning in rats (P < 0.001) in a time- and dose-dependent effects. Mechanistic studies revealed that glutamate evaluated the phosphorylation levels of JAK/STAT, while baicalin effectively inhibited the activation of the JAK/STAT signaling pathway. This study confirmed that baicalin protects against glutamate-induced oxidative stress damage in RGCs. It effectively alleviates oxidative stress and inflammatory responses, reduces cell apoptosis, and improves the pathological changes in the retina of rat models of RGCs damage, thereby decreasing RGCs death. Further exploration of its mechanism revealed that baicalin effectively inhibits the JAK/STAT signaling pathway, protecting RGCs from oxidative stress damage. This provides an experimental basis for the application of baicalin in the treatment of RGCs damage.