Research progress of Müller cells and retinal nerve regeneration / 国际眼科杂志(Guoji Yanke Zazhi)

@#Retinal degenerative diseases, a type of blinding eye diseases in which retinal neuron apoptosis is the main pathological process. Neuronal cells cannot be regenerated after damage, Müller cells are important glial cells of the retina and involved in retinal development, damage, and regeneration process. In recent years, studies have proved that Müller cells are an endogenous alternative source for stimulating damaged retinal neurons and an excellent target for retinal nerve regeneration. This article reviews the related factors of Müller cells and retinal nerve regeneration, and provides a new direction for nerve regeneration research.

Evolution of optic nerve and retina alterations in a child with indirect traumatic neuropathy as assessed by optical coherence tomography / Evolução das alterações no nervo óptico e na retina em criança com neuropatia traumática indireta avaliadas com tomografia de coerência óptica

ABSTRACT Herein, we describe the case of a 4-year-old child with indirect traumatic optic neuropathy and serial changes of the optic nerve head and retinal nerve fiber layer (RNFL) documented using optical coherence tomography (OCT). Visual acuity improved despite progressive RNFL thinning and optic disc pallor. We concluded that OCT may be useful for monitoring axonal loss but may not predict the final visual outcome.

RESUMO Descrição do caso de uma criança de 4 anos de idade com neuropatia óptica traumática indireta, cujas alterações no nervo óptico e na camada de fibras nervosas da retina foram documentadas com tomografia de coerência óptica seriadas. A acuidade visual apresentou melhora apesar da diminuição progressiva da camada de fibras nervosas e da palidez do disco óptico. Em conclusão, a tomografia de coerência óptica pode ser útil para monitorar a perda axonal na neuropatia óptica traumática indireta, sem no entanto, predizer o desfecho visual.

Relationship between peripheral neuropathy and retinal nerve fiber layer thickness in elderly patients with type 2 diabetes / 中华老年医学杂志

Objective To investigate the relationship between retinal nerve fiber layer thickness and peripheral neuropathy in elderly patients with type 2 diabetes.Methods Clinical data of elderly patients with T2DM in Endocrinology Department in Beijing Hospital were retrospectively collected.Global and sectorial retinal nerve fiber layer(RNFL)thicknesses were measured by using optical coherence tomography(OCT),and never conduction velocity measurements were performed in all patients.Diabetic peripheral neuropathy was diagnosed by the criteria in diabetic neuropathies update(2010,American Diabetes Association).RNFL thickness was compared between diabetic nonperipheral neuropathy group (control group,n =30)and diabetic peripheral neuropathy group (DPN group,n=17)and between different sub-groups.Results The RNFL thicknesses of temporal,nasal,superior and inferior visual fields and the mean RNFL thickness were less in DPN group than in control group,among which there were significant differences in the RNFL thicknesses of superior,inferior visual fields and the mean RNFL thickness [(107.7±27.4)μm vs.(128.1±17.3)μm,(112.9 ±20.8)μm vs.(130.8±21.8)μm,(88.2±15.5)μm vs.(100.5± 11.3)μm,F=7.446,7.468,7.988,respectively,P=0.009,0.009 and 0.007].RNFL thickness was decreased along with the aggravation of DPN from the control group,the subclinical DPN group to the DPN group successively(all P＜ 0.05).Conclusions Retinal nerve fiber layer thickness is associated with diabetic peripheral neuropathy in elderly patients with type 2 diabetes,and the relationship is more significant in patients with serious DPN.

P2X7 receptor and relationship with the death of retinal neurons / 中华眼底病杂志

Retinal neuronal cells are crucial in the formation of vision.Injury or death of these cells may lead to irreversible damage to visual function due to their low regenerative capacity.The P2X7 receptor is a trimeric adenosine triphosphate (ATP)-gated cation channel.Recent studies have shown that P2X7 receptor plays a role in retinal neuronal death.In a series of animal models,when exposed to conditions of hypoxia or ischemia,elevated ocular pressure,trauma and exogenous agonists,P2X7 receptor activated by extracellular ATP can cause death of retinal neuronal cells such as retinal ganglion cells and photoreceptor cells through direct or indirect pathways.Blocking the expression and function of P2X7 receptor by its specific antagonist and gene knocking-out,the loss of retinal neuronal cells is significantly attenuated.P2X7 receptor may become a potential novel neuroprotective target for diseases related to the loss of retinal neurons.

Towards objective assessment of the inner retinal functions / 中华实验眼科杂志

Retinal anatomic structure and physiology function are very complex.Electroretinogram (ERG) is currently the only objective assessment for retinal function.There are groups of devastating diseases characterized by affecting the inner retinal functions.However,compared with its advantages in evaluating the outer retina function,ERG is less sensitive in judging the inner retinal function.The decrease of sensitivity is mainly associated with the crosstalk between the rod and cone systems in the longer visual signal pathways.In the past twenty years,new recording techniques in ERG analysis including oscillatory potentials,ON-OFF responses,photopic negative responses and scotopic threshold response have been developed.These ERG components are generated from the bipolar cells,amacrine cells or retinal ganglion cells and are becoming novel tools to assess the function of the inner retina.Ophthalmologists should fully understand the clinical significance of these ERG components in assessing inner retinal function to better guide the diagnosis and treatment of retinal diseases.

Effect of Recombination Human Erythropoietin on the Apoptosis of Glutamate-induced Retinal Cells / 华中科技大学学报(医学版)

Objective To study the protective effect of recombination human erythropoietin (rhEPO) on the apoptosis of retinal neurons induced by glutamate.Methods The primary retinal neurons of postnatal SD rats were cultured in vitro for 7 days and divided into 3 groups :control group ,glutamate group and rhEPO pretreatment group.The neurons in the rhEPO pre-treatment group were afterwards allocated to three subgroups in terms of different rhEPO treatments (0.15 ,0.30 or 0.50 U/mL rhEPO for 12 h).Those in glutamate group and rhEPO pretreatment group were treated with glutamate at the concentration of 20μmol/L for 30 min for establishment of the apoptosis model.Twenty-four h later ,the apoptosis index (AI) was assayed by TUNEL and the expressions of BCL-xL mRNA and protein was detected by RT-PCR and immunocytochemistry respective-ly.Results The AI was significantly higher in the glutamate group than in the control group (P<0.01).The AI was signifi-cantly reduced ,and the expression level of BCL-xL mRNA and protein was markedly dose-dependently increased in the rhEPO pretreatment groups compared with the glutamate group (P<0.01).Conclusion The rhEPO pretreatment can inhibit the glu-tamate-induced apoptosis of retinal neurons by up-regulating the expression of BCL-xL .

Effects of the Center-Surround Light Stimuli on the Catfish Retianl Neurons

For the investigation of the receptive field of the retinal neurons, the spatial and temporal properties of horizontal cells and the center-surround antagonisms of bipolar cells and the third-order neurons were studied using conventional intracellular recording techniques. Horizontal cells were hyperpolarized by the large annulus light stimuli (id: 3.5mm) and required at least 0.2 seconds of dark periods to respond enough. The amplitudes of the response of the ON-bipolar cell were decreased as the diameter of the spot stimuli was increased to 2.6mm and the responses were inverted at 2.6mm of inner diameter of the spreading annulus stimuli with fixed width. ON-sustained cell with spikes generated ON-sustained light responses by small annulus (1400-2100micrometer), but elicited OFF-sustained responses by large annulus (2100-2800micrometer). ON-sustained cell without spikes also showed surround antagonism. The spikes were generated at the spot of 490micrometer diameter and they were disappeared at the spot of 5600micrometer diameter. And, OFF-transient component of the ON-OFF transient cell was enhanced as annulus stimuli spread. The results suggest that the horizontal cells have large and monotonic receptive fields while the bipolar cells and the ON-sustained cells have large biphasic receptive fields in the catfish retina.

Preferential Suppression of the On Pathway by r-Aminobutyric Acid in the Catfish Retina

The effects of r-aminobutyric acid(GABA) agonsits and antagonists were explored by the intracellular recording method to discern the preferential suppression of the ON component by GABA on the ON-OFF transient cell in the catfish (Ictalurus punctatus) retina. Experiments were performed in the superfused eyecup preparation. The animals were decapitated and pited before the eye, and the surrounding tissue was removed from the skull. The retina was exposed by excising the cornea, iris, and vitreous. This preparation rested on a wad of Ringer`s soaked cotton in contact with an Ag/Agcl reference electrode. Solutions were delivered through a manifold system that was connected to a pipette located near the absorbent wick. Electro-physiological recordings were made using standard intracellular electrodes filled with 2 M potassium acetate. The electrical signal was recorded with an amplifierand a penwriter, viewed on an oscilloscope, and stored on a data recorder. The light sources were red light-emitting-diode (LED) and the stimuli were full field illumination covering the cntire retina. GABA preferentially reduced ON light responses in ON-OFF transient cell. and GABA hyperpolarized bipolar cells, but the effects on ON bipolar cells were more sensitive than OFF bipolar cells. CACA and TACA, GABAc receptor agonist, did not act on bipolar cells. CACA and TACA, GABAc receptor agonists, hyperpolarized bipolar cells but the sensitivity deferences between ON and OFF bipolar cell were not observed. These results suggest that the preferential suppression of the ON component of the ON-OFF transient cell by GABA was resulted from the presynaptic mechanism that reduced bipolar cell input.

Mechanism of Hypoxia-Induced Cytotoxicity in Cultured Rat Retinal Neurons

Retinal neurons are highly vulnerable to hypoxia/ischemia. Excitotoxicity and free radical injury have been proposed as the major mechanisms of ischemic retinal injury have been proposed as the major mechanisms of ischemic retinal neuronal death. In the present study, we examined these possibilities in retinal cultures. Exposure of these cultures to hypoxia for 48 hr induced selective death of neurons. Addition of an antioxidiant trolox markedly attenuated hypoxiainduced retinal neuronal death, whereas addition of glutamate antagonists, MK-801 or CNQX,did not. Morphologically, hypoxic neuronal death in cultures was accompanied by cell body swelling, a feature of necrosis, yet simultaneously exhibited some features of apoptosis such as TUNEL positivity and protection by cycloheximide. However, unlike in classical programmed cell death, adding buthionine sulfoximine, a potent inhibitor of glutathione synthesis, completely reversed the protective effect of cycloheximide. The results have demonstrated that free radical injury is the main mechanism of neuronal death in the present retinal culture, and suggest an intriguing possibility that free redical injury may become a prominent mechanism, when excitotoxic injury is masked.

Effects of Extracellular Chloride Ions on the Catfish Retinal Neurons

The catfish (Ictalurus punctatus) retinal neurons were investigated by using the intracellular recording techniques to analyze the function of the chloride ions in the light responses and the ionic mechanisms of the depolarizing actions by GABA. Experiments were performed in the superfused retina-eyecup preparation. The retina was exposed by exicising the cornea, iris, and vitreous. A piece of absorbent tissue with a hole large enough to expose the retina was centered over the eyecup to serve as a wick to draw off the superfusate. Diffuse light stimuli were generated by light-emitting diode positioned above the eyecup. The recordings were made with the use of borosilicate glass micropipettes fashioned from' omega dot' capillary tubing filled with 2 M potassium acetate. Voltage recordings were obtained using an amplifier and amplified signals were recorded on a storage oscillocope, penwriter, and a data recorder. In the catfish retina, the dark membrane potentials were depolarized and the light evoked responses were enhanced in the chloride"-free medium on the catfish horizontal cells. The amplitude of the light evoked potentials were increased by chloride free Ringer's solution on the ON- and OFF-bipolar cells. But the dark membrane potentials were hyperpolarized on the ON-bipolar cell and depolarized on the OFF-bipolar cells in the chloride free medium. The chloride free Ringer's solution changed the light response from ON-sustained to OFF-sustained without any change in amplitude on the ON-sustained cell. The depolarizing actions by GABA on the horizontal cells were maintained in chloride-free environment. But GABA did not abolished the light evoked potentials of the horizontal cell and the ON-sustained cell under the chloride free environment. The results suggest that chloride ion has important roles on the signal transmission of the dark periods in the catfish retina and the depolarizing actions by GABA on the neurons in the catfish retina might be chloride dependent.

THE GROWTH EFFECT OF TECTAL EXTRACT ON NEONATAL RAT RETINAL NEURONS CULTURED ON VARIOUS SUBSTRATA / 解剖学报

The retinal cells from 3-4 days neonatal rats were isolated and cultured on human amniotic basement membrane (HABM), laminin (LN), and polyornithine (PO) as the substrata. We have studied the morphology of these cultures and quantified the survival and growth of these cells in the absence and presence of tectal extract (Te) by MTT automatic colorimetric microassay. Neurons were identified by using the neuron specific enolase (NSE) immunocytochemical staining. The results showed that after 48 hrs culturing, some retinal cells grew larger and more actively on HABM, LN and PO in the presence of Te as compared to the controls without Te; the number of retinal cells with diameter above 10 ?m grown on HABM and LN with Te had increased 3 times compared to the controls without Te. MTT optical density (OD) results indicated that between the cell density range from 7?10~4 to 1.2?10~5 per well, the retinal cell cultures with Te gave significantly higher OD values than those controls without (P