• Molecules and Cells
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• 제39권2호
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• pp.136-140
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• 2016

Eph receptors and their ligands, ephrins, mediate cell-to-cell contacts in a specific brain region and their bidirectional signaling is implicated in the regulation of apoptosis during early brain development. In this report, we used the alpha(${\alpha}$)-Cre transgenic line to induce ephrin-A5 over-expression in the distal region of the neural retina. Using this double transgenic embryo, we show that the over-expression of ephrin-A5 was responsible for inducing massive apoptosis in both the nasal and temporal retinas. In addition, the number of differentiated retinal neurons with the exception of the bipolar neuron was significantly reduced, whereas the laminar organization of the mature retina remained intact. Consistent with this finding, an analysis of the mature retina revealed that the size of the whole retina-particularly the nasal and temporal regions-is markedly reduced. These results strongly suggest that the level of ephrin-A5 expression plays a role in the regulation of the size of the retinal progenitor pool in the neural retina.

• Applied Microscopy
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• 제50권
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• pp.11.1-11.3
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• 2020

The human turbinate-derived mesenchymal stem cells (hTMSCs), which were DiI-labeled and transplanted into the subretinal space in degenerating mouse retina, were observed in retinal vertical sections processed for rhodopsin (a marker for rod photoreceptor) by confocal microscope with differential interference contrast (DIC) filters. The images clearly demonstrated that DiI-labeled hTMSCs have rhodopsin-immunoreactive appendages, indicating differentiation of transplanted hTMSC into rod photoreceptor. Conclusively, the finding suggests therapeutic potential of hTMSCs in retinal degeneration.

• BMB Reports
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• 제48권5호
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• pp.289-294
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• 2015

Caesalpinia sappan is a well-distributed plant that is cultivated in Southeast Asia, Africa, and the Americas. C. sappan has been used in Asian folk medicine and its extract has been shown to have pharmacological effects. Two homoisoflavonoids, sappanol and brazilin, were isolated from C. sappan by using centrifugal partition chromatography (CPC), and tested for protective effects against retinal cell death. The isolated homoisoflavonoids produced approximately 20-fold inhibition of N-retinylidene-N-retinyl-ethanolamine (A2E) photooxidation in a dose-dependent manner. Of the 2 compounds, brazilin showed better inhibition (197.93 ± 1.59 μM of IC₅₀). Cell viability tests and PI/Hoechst 33342 double staining method indicated that compared to the negative control, sappanol significantly attenuated H₂O₂-induced retinal death. The compounds significantly blunted the up-regulation of intracellular reactive oxygen species (ROS), and sappanol inhibited lipid peroxidation in a concentration-dependent manner. Thus, both compounds represent potential antioxidant treatments for retinal diseases. [BMB Reports 2015; 48(5): 289-294]

• Applied Microscopy
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• 제27권4호
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• pp.357-372
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• 1997

To study the age-related morphological differences of the retinal pigment cells and Bruch's membrane of mouse, retinae of one week-old, five weeks-old, eight weeks-old, six months-old, twelve months-old, eighteen months-old, twenty-four months-old and thirty months-old ICR mice were dissected out under anesthesia. Pieces of the tissue taken from the posterior region of the retina were fixed in 2.5% glutaraldehyde-1.5% paraformaldehyde (0.1 M Millonig's phosphate buffer, pH 7.3), and 1% osmium tetroxide (0.1 M Millonig's phosphate buffer, pH 7.3), and embedded in araldite mixture. The ultrathin sections were stained with uranyl acetate and lead citrate, and were observed under a JEM 100 CX-II electron microscope. Observed results were as follows: 1. Retinae of one week old mouse exhibit that some parts of the pigment cell provided with basal foldings, whereas other parts of the one contain without basal foldings. After (ive weeks-old, all retinal pigment cells have the basal infoldings. 2. In the one week-old, stage 1 and stage 2 melanosomes were observed in the retinal pigments cells, but after five weeks-old, most of the retinal pigment cells contain some matured stage melanosomes (stage III and stage IV). 3. The phagosomes in the retinal pigment cells were increased during aging. 4. After eighteen months-old, electron dense materials are observed within the basal infoldings. 5. After eighteen months-old, the thickness of the Bruch's membrane is prominently increased. The thickness of the basal laminae of the pigment cell and the choriocapillary endothelium is more prominently increased as compared with that of the other components of the Bruch's membrane. 6. The thickness of the basal lamina of the pigment cell is more prominently increased as compared with that of the choriocapillary endothelium on aging. From the above results, it was suggested that the pigment cell and Bruch's membrane matures structurally In five weeks, and the function of the pigment cell is prominently suppressed around eighteen months-old, and thereafter the functional suppression is continued on aging.

• 한국안광학회지
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• 제1권1호
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• pp.15-22
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• 1996

본 연구는 망막조직의 미세구조를 전자현미경을 이용하여, 생쥐(ICR)에 대한 Laser 조사의 영향을 조사하였다. 그 결과는 다음과 같다. l. 정상군에서 대개의 망막층은 여러 특수한 세포들과 신경섬유로 구성된 복잡한 구조를 가지고 있었다. 2. Laser 조사의 기간이 길어질수록, 망막의 각 세포의 층과 구조는 일정한 형태를 나타내지 못했다. 시세포 visual cell들은 심하게 이형염색질체 heterochromatin이며, 세포질은 종대되며, 핵의 모양은 불규칙적이며,일부의 세포질은 소실되었다. 망막층의 핵과 신경섬유는 매우 불규칙적이며, 소포의 형성, 각 세포간 경계의 불명확함이 있었다. 색소상피세포 pigment epithelail cell들은 정상모양이 아니며, 세포질에는 큰 공포 형성이 있으며, 핵의 응축과 불규칙한 모양 등이 있었다.

• 한국안광학회지
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• 제16권1호
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• pp.91-95
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• 2011

목적: 본 연구는 토끼 망막에서 특정 신경 세포 염색이 가능한 염료를 조사하였다. 방법: Rhodamine B를 토끼의 안구내 유리체강에 주입하였다. 24시간 후, 망막을 분리하여 현미경으로 염색 상태를 관찰하였다. 염색 된 세포는 그 종류를 알아보기 위하여 면역조직화학적방법을 실시하였다. 결과: 망막 내핵층 중간 위치에서 선명하게 염색된 핵들이 관찰되었다. 염색된 세포의 분포도와 수가 뮬러세포와 비슷한 양상을 보였다. 뮬러세포인지 확인하기 위하여 vimentin 항체를 사용하였다. Rhodamine B에 의해 염색된 핵들은 vimentin 항체로 감싸져 있어 뮬러세포임을 확인하였다. 결론: Rhodamine B를 살아있는 망막에 넣을 경우 토끼 망막에 신경교세포의 특이적 염색이 나타났다.

• Applied Microscopy
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• 제28권3호
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• pp.391-398
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• 1998

The morphological phenotype on ocellus of Drosophila rdgC mutant was observed with electron microscope. The result showed the particular phenotype that was not found in other retinal degenarative mutants. The most distinct difference was the orientation of photoreceptor cells. The photoreceptor cells did not attached to corneagenous cells but dropped under corneagenous cells and assembled around newly formed space. Enormous multivesicle bodies caused by the degeneration of photoreceptor cells were frequently found. Rhabdomeres were also severely degenerated in consequence of the mutant. Another degeneration was found in a part of photoreceptor cell, but the degeneration of subrhabdomeric cisternae (SRC) was not found. It was a ovious difference of rdgC comparing with other two retinal degenerative mutants, rdgA and rdgB. As a result, rdgC mutant was affected on the attachment between photoreceptor cells and corneageneous cells, and it suggested the defect of cell-cell attachment. In addition, rdgC mutant was accompanied by the defect not only in retina but nerve system. The results were agreed to the reference discussion that the rdgC molecule is exist in the nerve.

• The Korean Journal of Physiology and Pharmacology
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• 제21권5호
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• pp.555-563
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• 2017

Electrical stimulation through retinal prosthesis elicits both short and long-latency retinal ganglion cell (RGC) spikes. Because the short-latency RGC spike is usually obscured by electrical stimulus artifact, it is very important to isolate spike from stimulus artifact. Previously, we showed that topographic prominence (TP) discriminator based algorithm is valid and useful for artifact subtraction. In this study, we compared the performance of forward backward (FB) filter only vs. TP-adopted FB filter for artifact subtraction. From the extracted retinae of rd1 mice, we recorded RGC spikes with $8{\times}8$ multielectrode array (MEA). The recorded signals were classified into four groups by distances between the stimulation and recording electrodes on MEA (200-400, 400-600, 600-800, $800-1000{\mu}m$). Fifty cathodic phase-$1^{st}$ biphasic current pulses (duration $500{\mu}s$, intensity 5, 10, 20, 30, 40, 50, $60{\mu}A$) were applied at every 1 sec. We compared false positive error and false negative error in FB filter and TP-adopted FB filter. By implementing TP-adopted FB filter, short-latency spike can be detected better regarding sensitivity and specificity for detecting spikes regardless of the strength of stimulus and the distance between stimulus and recording electrodes.

• The Korean Journal of Physiology and Pharmacology
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• 제15권6호
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• pp.415-422
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• 2011

Previously, we reported that besides retinal ganglion cell (RGC) spike, there is ~10 Hz oscillatory rhythmic activity in local field potential (LFP) in retinal degeneration model, rd1 mice. The more recently identified rd10 mice have a later onset and slower rate of photoreceptor degeneration than the rd1 mice, providing more therapeutic potential. In this study, before adapting rd10 mice as a new animal model for our electrical stimulation study, we investigated electrical characteristics of rd10 mice. From the raw waveform of recording using $8{\times}8$ microelectrode array (MEA) from in vitro-whole mount retina, RGC spikes and LFP were isolated by using different filter setting. Fourier transform was performed for detection of frequency of bursting RGC spikes and oscillatory field potential (OFP). In rd1 mice, ~10 Hz rhythmic burst of spontaneous RGC spikes is always phase-locked with the OFP and this phase-locking property is preserved regardless of postnatal ages. However, in rd10 mice, there is a strong phase-locking tendency between the spectral peak of bursting RGC spikes (~5 Hz) and the first peak of OFP (~5 Hz) across different age groups. But this phase-locking property is not robust as in rd1 retina, but maintains for a few seconds. Since rd1 and rd10 retina show phase-locking property at different frequency (~10 Hz vs. ~5 Hz), we expect different response patterns to electrical stimulus between rd1 and rd10 retina. Therefore, to extract optimal stimulation parameters in rd10 retina, first we might define selection criteria for responding rd10 ganglion cells to electrical stimulus.

• The Korean Journal of Physiology and Pharmacology
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• 제27권6호
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• pp.541-553
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• 2023

Retinal prostheses have shown some clinical success in restoring vision in patients with retinitis pigmentosa. However, the post-implantation visual acuity does not exceed that of legal blindness. The reason for the poor visual acuity might be that (1) degenerate retinal ganglion cells (RGCs) are less responsive to electrical stimulation than normal RGCs, and (2) electrically-evoked RGC spikes show a more widespread not focal response. The single-biphasic pulse electrical stimulation, commonly used in artificial vision, has limitations in addressing these issues. In this study, we propose the benefit of multiple consecutive-biphasic pulse stimulation. We used C57BL/6J mice and C3H/HeJ (rd1) mice for the normal retina and retinal degeneration model. An 8 × 8 multi-electrode array was used to record electrically-evoked RGC spikes. We compared RGC responses when increasing the amplitude of a single biphasic pulse versus increasing the number of consecutive biphasic pulses at the same stimulus charge. Increasing the amplitude of a single biphasic pulse induced more RGC spike firing while the spatial resolution of RGC populations decreased. For multiple consecutive-biphasic pulse stimulation, RGC firing increased as the number of pulses increased, and the spatial resolution of RGC populations was well preserved even up to 5 pulses. Multiple consecutive-biphasic pulse stimulation using two or three pulses in degenerate retinas induced as much RGC spike firing as in normal retinas. These findings suggest that the newly proposed multiple consecutive-biphasic pulse stimulation can improve the visual acuity in prosthesis-implanted patients.