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https://www.readbyqxmd.com/read/29102785/melanopsin-expressing-retinal-ganglion-cells-are-relatively-resistant-to-excitotoxicity-induced-by-n-methyl-d-aspartate
#1
Songtao Wang, Dandan Gu, Peng Zhang, Jing Chen, Yan Li, Honglei Xiao, Guomin Zhou
Excitotoxicity plays an important role in neuronal loss in glaucoma. Previous studies indicate melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) are more injury-resistant. However, whether melanopsin-expressing ipRGCs are resistant to N-methyl-d-aspartate (NMDA) induced excitotoxicity is not well understood. In the present study, we investigated the effects of NMDA-induced excitotoxicity in conventional retinal ganglion cells (RGCs) and melanopsin-expressing ipRGCs in adult mice...
November 2, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/29070825/melanopsin-a-canonical-light-receptor-mediates-thermal-activation-of-clock-genes
#2
Maria Nathália Moraes, Leonardo Vinícius Monteiro de Assis, Keila Karoline Magalhães-Marques, Maristela Oliveira Poletini, Leonardo Henrique Ribeiro Graciani de Lima, Ana Maria de Lauro Castrucci
Melanopsin (OPN4) is a photo-pigment found in a small subset of intrinsically photosensitive ganglion cells (ipRGCs) of the mammalian retina. These cells play a role in synchronizing the central circadian pacemaker to the astronomical day by conveying information about ambient light to the hypothalamic suprachiasmatic nucleus, the site of the master clock. We evaluated the effect of a heat stimulus (39.5 °C) on clock gene (Per1 and Bmal1) expression in cultured murine Melan-a melanocytes synchronized by medium changes, and in B16-F10 melanoma cells, in the presence of the selective OPN4 antagonist AA92593, or after OPN4 knockdown by small interfering RNA (siRNA)...
October 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29049724/patients-with-normal-tension-glaucoma-have-relative-sparing-of-the-relative-afferent-pupillary-defect-compared-to-those-with-open-angle-glaucoma-and-elevated-intraocular-pressure
#3
COMPARATIVE STUDY
Mitchell Lawlor, Ana Quartilho, Catey Bunce, Neil Nathwani, Emily Dowse, Debbie Kamal, Gus Gazzard
Purpose: We determined whether there is relative sparing of pupil function in glaucoma patients with normal pressures compared to those with high pressures. Methods: A cross-sectional study was done of 68 patients with primary open angle glaucoma (POAG): 38 had normal IOPs on all-day phasing before treatment (never >21 mm Hg), with confirmed progression of glaucomatous optic neuropathy (NTG) and 30 had glaucomatous optic neuropathy associated with elevated intraocular pressures (>25 mm Hg; HP-POAG)...
October 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29041976/human-pupillary-light-reflex-during-successive-irradiation-with-1-ms-blue-and-green-pulsed-light
#4
Soomin Lee, Naoko Muto, Yoshihiro Shimomura, Tetsuo Katsuura
BACKGROUND: In the human retina, the contribution of intrinsically photosensitive retinal ganglion cells (ipRGCs) to the regulation of the pupillary response remains poorly understood. The objective of the current study was to determine the response dynamics of the pupillary light reflex to short, successive pulses of light. In order to better assess the roles of ipRGCs and cones, we used pulses of blue and green light. METHODS: Each participant was exposed to 1-ms blue (466 nm) and/or green (527 nm) light pulses simultaneously or separately, with inter-stimulus intervals (ISIs) of 0, 250, 500, 750, or 1000 ms...
October 17, 2017: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/28994267/pupillary-light-reflex-and-circadian-synchronization-in-the-elderly
#5
Philipp Novotny, Herbert Plischke
Most elderly lack a synchronized circadian rhythm and often cannot benefit from light therapy. Non-visual effects of light are mediated through intrinsic photosensitive retinal ganglion cells (ipRGCs). With chromatic pupillometry, the functionality of ipRGCs and their functional circuit in the brain can be tested.
October 10, 2017: PsyCh Journal
https://www.readbyqxmd.com/read/28965762/a-population-representation-of-absolute-light-intensity-in-the-mammalian-retina
#6
Elliott Scott Milner, Michael Tri Hoang Do
Environmental illumination spans many log units of intensity and is tracked for essential functions that include regulation of the circadian clock, arousal state, and hormone levels. Little is known about the neural representation of light intensity and how it covers the necessary range. This question became accessible with the discovery of mammalian photoreceptors that are required for intensity-driven functions, the M1 ipRGCs. The spike outputs of M1s are thought to uniformly track intensity over a wide range...
November 2, 2017: Cell
https://www.readbyqxmd.com/read/28910447/orexin-a-suppresses-signal-transmission-to-dopaminergic-amacrine-cells-from-outer-and-inner-retinal-photoreceptors
#7
Sheng-Nan Qiao, Wei Zhou, Lei-Lei Liu, Dao-Qi Zhang, Yong-Mei Zhong
Purpose: The neuropeptides orexin-A and orexin-B are widely expressed in the vertebrate retina; however, their role in visual function is unclear. This study investigates whether and how orexins modulate signal transmission to dopaminergic amacrine cells (DACs) from both outer retinal photoreceptors (rods and cones) and inner retinal photoreceptors (melanopsin-expressing intrinsically photosensitive retinal ganglion cells [ipRGCs]). Methods: A whole-cell voltage-clamp technique was used to record light-induced responses from genetically labeled DACs in flat-mount mouse retinas...
September 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28871236/non-visual-photopigments-effects-of-constant-light-emitting-diode-light-exposure-on-the-inner-retina-of-wistar-rats
#8
María M Benedetto, Mario E Guido, María A Contin
The retina is part of the central nervous system specially adapted to capture light photons and transmit this information to the brain through photosensitive retinal cells involved in visual and non-visual activities. However, excessive light exposure may accelerate genetic retinal diseases or induce photoreceptor cell (PRC) death, finally leading to retinal degeneration (RD). Light pollution (LP) caused by the characteristic use of artificial light in modern day life may accelerate degenerative diseases or promote RD and circadian desynchrony...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28860528/pupillary-responses-to-light-are-not-affected-by-narrow-irido-corneal-angles
#9
A V Rukmini, Raymond P Najjar, Eray Atalay, Sourabh Sharma, Jing Zhan Lock, Mani Baskaran, Monisha Nongpiur, Joshua J Gooley, Tin Aung, Dan Milea
Chromatic pupillometry is an emerging method for evaluating ocular health that relies upon the differential stimulation of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). Although it has been investigated in conditions affecting the outer or inner retina, there is a paucity of studies in conditions where the anterior chamber of the eye is affected. Primary angle closure suspects (PACS) are defined as eyes with narrow anterior chamber angles and intact retina. PACS patients are at risk of developing primary angle closure glaucoma and are prophylactically treated by performing laser peripheral iridotomy (LPI)...
August 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28730123/iprgcs-possible-causation-accounts-for-the-higher-prevalence-of-sleep-disorders-in-glaucoma-patients
#10
Zhen-Zhen Guo, Shan-Ming Jiang, Li-Ping Zeng, Li Tang, Ni Li, Zhu-Ping Xu, Xin Wei
Sleep accounts for a third of one's lifetime, partial or complete deprivation of sleep could elicit sever disorders of body function. Previous studies have reported the higher prevalence of sleep disorders in glaucoma patients, but the definite mechanism for this phenomenon is unknown. On the other hand, it is well known by us that the intrinsically photosensitive retinal ganglion cells (ipRGCs) serve additional ocular functions, called non-image-forming (NIF) functions, in the regulation of circadian rhythm, melatonin secretion, sleep, mood and others...
2017: International Journal of Ophthalmology
https://www.readbyqxmd.com/read/28716667/pupillometric-evaluation-of-the-melanopsin-containing-retinal-ganglion-cells-in-mitochondrial-and-non-mitochondrial-optic-neuropathies
#11
Shakoor Ba-Ali, Henrik Lund-Andersen
In recent years, chromatic pupillometry is used in humans to evaluate the activity of melanopsin expressing intrinsic photosensitive retinal ganglion cells (ipRGCs). Blue light is used to stimulate the ipRGCs and red light activates the rod/cone photoreceptors. The late re-dilation phase of pupillary light reflex is primarily driven by the ipRGCs. Optic neuropathies i.e. Leber hereditary optic neuropathy (LHON), autosomal dominant optic atrophy (ADOA), nonarteritic anterior ischemic optic neuropathy (NAION), glaucoma, optic neuritis and idiopathic intracranial hypertension (IIH) are among the diseases, which have been subject to pupillometric studies...
July 14, 2017: Mitochondrion
https://www.readbyqxmd.com/read/28708670/color-pupillography-in-dorsal-midbrain-syndrome
#12
Carina B Kelbsch, Fumiatsu Maeda, Torsten Strasser, Tobias M Peters, Barbara J C Wilhelm, Helmut M Wilhelm
OBJECTIVE: The purpose of this study was to evaluate the pupil response to chromatic stimuli in patients with lesions in the dorsal midbrain and possibly gain new insights into the afferent pupillary pathways. METHODS: Color pupillography was performed in 5 patients with dorsal midbrain syndrome (DMS), and their results were compared with those of 20 healthy control subjects. We used full-field red stimuli (605 nm) that primarily address the rod/cone system and blue stimuli (420 nm) that preferentially activate intrinsically photosensitive retinal ganglion cells (ipRGCs) directly, with a duration of 4 seconds and a stimulus intensity of 28 lx corneal illumination under mesopic conditions...
September 2017: Journal of Neuro-ophthalmology: the Official Journal of the North American Neuro-Ophthalmology Society
https://www.readbyqxmd.com/read/28688906/effects-of-photopic-and-cirtopic-illumination-on-steady-state-pupil-sizes
#13
Feng Rao, A H S Chan, Xi-Fang Zhu
The conventional view was that cones are responsible for pupil constriction in photopic lighting conditions. With the discovery of intrinsically photosensitive retinal ganglion cells (ipRGC), it was found that signals from ipRGCs along with cones mediated the pupil light reflex in photopic lighting conditions. Although both signals contributed, it was unclear how these signals were summed. In the work reported here, steady-state pupil size was measured with an infrared camera under LED lighting conditions with different color temperatures and luminance...
July 11, 2017: Vision Research
https://www.readbyqxmd.com/read/28687871/chromatic-pupillography-in-hemianopia-patients-with-homonymous-visual-field-defects
#14
Fumiatsu Maeda, Carina Kelbsch, Torsten Straßer, Karolína Skorkovská, Tobias Peters, Barbara Wilhelm, Helmut Wilhelm
PURPOSE: The pupil light reflex is considered to be a simple subcortical reflex. However, many studies have proven that patients with isolated occipital lesions with homonymous hemianopia show pupillary hemihypokinesia. Our hypothesis is that the afferent pupillary system consists of two pathways: one via intrinsically photosensitive retinal ganglion cells (ipRGCs), the other running through the normal RGCs via the visual cortex. The purpose of this study was to test the hypothesis of these two separate pupillomotor pathways...
June 30, 2017: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/28656675/attenuation-of-short-wavelengths-alters-sleep-and-the-iprgc-pupil-response
#15
Lisa A Ostrin, Kaleb S Abbott, Hope M Queener
PURPOSE: Exposure to increasing amounts of artificial light during the night may contribute to the high prevalence of reported sleep dysfunction. Release of the sleep hormone melatonin is mediated by the intrinsically photosensitive retinal ganglion cells (ipRGCs). This study sought to investigate whether melatonin level and sleep quality can be modulated by decreasing night-time input to the ipRGCs. METHODS: Subjects (ages 17-42, n = 21) wore short wavelength-blocking glasses prior to bedtime for 2 weeks...
July 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28649427/global-rise-of-potential-health-hazards-caused-by-blue-light-induced-circadian-disruption-in-modern-aging-societies
#16
REVIEW
Megumi Hatori, Claude Gronfier, Russell N Van Gelder, Paul S Bernstein, Josep Carreras, Satchidananda Panda, Frederick Marks, David Sliney, Charles E Hunt, Tsuyoshi Hirota, Toshiharu Furukawa, Kazuo Tsubota
Mammals receive light information through the eyes, which perform two major functions: image forming vision to see objects and non-image forming adaptation of physiology and behavior to light. Cone and rod photoreceptors form images and send the information via retinal ganglion cells to the brain for image reconstruction. In contrast, nonimage-forming photoresponses vary widely from adjustment of pupil diameter to adaptation of the circadian clock. nonimage-forming responses are mediated by retinal ganglion cells expressing the photopigment melanopsin...
2017: NPJ Aging and Mechanisms of Disease
https://www.readbyqxmd.com/read/28629848/a-novel-intrinsic-electroretinogram-response-in-isolated-mouse-retina
#17
Motoharu Takao, Yumi Fukuda, Takeshi Morita
Since the discovery of intrinsic photosensitive retinal ganglion cell (ipRGC) was reported in 2002, many features specific to this cell type have been described. However, scare information is available on the retinographic components directly reflecting ipRGC activity. In this study, we identified the electroretinogram (microERG) that reflects the photoresponses by ipRGCs in ex vivo preparations of the mouse retina, in which classical photoreceptors (cones and rods) were ablated mechanically and photochemically...
June 17, 2017: Neuroscience
https://www.readbyqxmd.com/read/28617242/a-subset-of-iprgcs-regulates-both-maturation-of-the-circadian-clock-and-segregation-of-retinogeniculate-projections-in-mice
#18
Kylie S Chew, Jordan M Renna, David S McNeill, Diego C Fernandez, William T Keenan, Michael B Thomsen, Jennifer L Ecker, Gideon S Loevinsohn, Cassandra VanDunk, Daniel C Vicarel, Adele Tufford, Shijun Weng, Paul A Gray, Michel Cayouette, Erik D Herzog, Haiqing Zhao, David M Berson, Samer Hattar
The visual system consists of two major subsystems, image-forming circuits that drive conscious vision and non-image-forming circuits for behaviors such as circadian photoentrainment. While historically considered non-overlapping, recent evidence has uncovered crosstalk between these subsystems. Here, we investigated shared developmental mechanisms. We revealed an unprecedented role for light in the maturation of the circadian clock and discovered that intrinsically photosensitive retinal ganglion cells (ipRGCs) are critical for this refinement process...
June 15, 2017: ELife
https://www.readbyqxmd.com/read/28578927/synergistic-signaling-by-light-and-acetylcholine-in-mouse-iris-sphincter-muscle
#19
Qian Wang, Wendy Wing Sze Yue, Zheng Jiang, Tian Xue, Shin H Kang, Dwight E Bergles, Katsuhiko Mikoshiba, Stefan Offermanns, King-Wai Yau
The mammalian pupillary light reflex (PLR) involves a bilateral brain circuit whereby afferent light signals in the optic nerve ultimately drive iris-sphincter-muscle contraction via excitatory cholinergic parasympathetic innervation [1, 2]. Additionally, the PLR in nocturnal and crepuscular sub-primate mammals has a "local" component in the isolated sphincter muscle [3-5], as in amphibians, fish, and bird [6-10]. In mouse, this local PLR requires the pigment melanopsin [5], originally found in intrinsically photosensitive retinal ganglion cells (ipRGCs) [11-19]...
June 19, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28535270/intrinsically-photosensitive-retinal-ganglion-cell-function-sleep-efficiency-and-depression-in-advanced-age-related-macular-degeneration
#20
Michelle L Maynard, Andrew Zele, Anthony Kwan, Beatrix Feigl
Purpose: Melanopsin expressing intrinsically photosensitive retinal ganglion cells (ipRGC) input to multiple brain regions including those for pupil control, circadian rhythms, sleep and mood regulation. Here we measured ipRGC function and its relationship to sleep quality and depression in patients with advanced AMD. Methods: The melanopsin-mediated post-illumination pupil response (PIPR) was measured in 53 patients with advanced AMD (age 78.8 ± 8.8 years) and in 20 healthy controls (age 72...
February 1, 2017: Investigative Ophthalmology & Visual Science
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