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https://www.readbyqxmd.com/read/29773814/melanopsin-mediated-pupil-function-is-impaired-in-parkinson-s-disease
#1
Daniel S Joyce, Beatrix Feigl, Graham Kerr, Luisa Roeder, Andrew J Zele
Parkinson's disease (PD) is characterised by non-motor symptoms including sleep and circadian disruption. Melanopsin-expressing intrinsically photosensitive Retinal Ganglion Cells (ipRGC) transmit light signals to brain areas controlling circadian rhythms and the pupil light reflex. To determine if non-motor symptoms observed in PD are linked to ipRGC dysfunction, we evaluated melanopsin and rod/cone contributions to the pupil response in medicated participants with PD (n = 17) and controls (n = 12)...
May 17, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29756029/circadian-behavioral-responses-to-light-and-optic-chiasm-evoked-glutamatergic-epscs-in-the-suprachiasmatic-nucleus-of-iprgc-conditional-vglut2-knock-out-mice
#2
Michael G Moldavan, Patricia J Sollars, Michael R Lasarev, Charles N Allen, Gary E Pickard
Intrinsically photosensitive retinal ganglion cells (ipRGCs) innervate the hypothalamic suprachiasmatic nucleus (SCN), a circadian oscillator that functions as a biological clock. ipRGCs use vesicular glutamate transporter 2 (vGlut2) to package glutamate into synaptic vesicles and light-evoked resetting of the SCN circadian clock is widely attributed to ipRGC glutamatergic neurotransmission. Pituitary adenylate cyclase-activating polypeptide (PACAP) is also packaged into vesicles in ipRGCs and PACAP may be coreleased with glutamate in the SCN...
May 2018: ENeuro
https://www.readbyqxmd.com/read/29718372/defining-the-impact-of-melanopsin-missense-polymorphisms-using-in-vivo-functional-rescue
#3
Jessica Rodgers, Steven Hughes, Carina A Pothecary, Laurence A Brown, Doron G Hickey, Stuart N Peirson, Mark W Hankins
Melanopsin (OPN4) is an opsin photopigment expressed within intrinsically photosensitive retinal ganglion cells (ipRGCs) that mediate non-image forming (NIF) responses to light. Two single nucleotide polymorphisms (SNPs) in human melanopsin (hOPN4), Pro10Leu and Thr394Ile, have recently been associated with abnormal NIF responses to light, including Seasonal Affective Disorder. It has been suggested these behavioural changes are due to altered melanopsin signalling. However, there is currently no direct evidence to support this...
April 30, 2018: Human Molecular Genetics
https://www.readbyqxmd.com/read/29691928/circadian-rhythms-refractive-development-and-myopia
#4
Ranjay Chakraborty, Lisa A Ostrin, Debora L Nickla, P Michael Iuvone, Machelle T Pardue, Richard A Stone
PURPOSE: Despite extensive research, mechanisms regulating postnatal eye growth and those responsible for ametropias are poorly understood. With the marked recent increases in myopia prevalence, robust and biologically-based clinical therapies to normalize refractive development in childhood are needed. Here, we review classic and contemporary literature about how circadian biology might provide clues to develop a framework to improve the understanding of myopia etiology, and possibly lead to rational approaches to ameliorate refractive errors developing in children...
May 2018: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/29625838/suppression-of-melatonin-secretion-in-totally-visually-blind-people-by-ocular-exposure-to-white-light-clinical-characteristics
#5
Joseph T Hull, Charles A Czeisler, Steven W Lockley
PURPOSE: Although most totally visually blind individuals exhibit nonentrained circadian rhythms due to an inability of light to entrain the circadian pacemaker, a small proportion retain photic circadian entrainment, melatonin suppression, and other nonimage-forming responses to light. It is thought that these responses to light persist because of the survival of melanospin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), which project primarily to the circadian pacemaker and are functionally distinct from the rod and cone photoreceptors that mediate vision...
April 3, 2018: Ophthalmology
https://www.readbyqxmd.com/read/29625463/taurine-depletion-causes-iprgc-loss-and-increases-light-induced-photoreceptor-degeneration
#6
Diego García-Ayuso, Johnny Di Pierdomenico, Wahiba Hadj-Said, Mélanie Marie, Marta Agudo-Barriuso, Manuel Vidal-Sanz, Serge Picaud, María P Villegas-Pérez
Purpose: To examine if light exposure exacerbates retinal neuronal loss induced by taurine depletion. Methods: Albino rats received β-alanine in the drinking water to induce taurine depletion. One month later, half of the animals were exposed to white light (3000 lux) continuously for 48 hours and the rest remained in normal environmental conditions. A control group of animals nontreated with β-alanine also was prepared, and half of them were exposed to light using the same protocol...
March 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29603954/evidence-for-an-impact-of-melanopsin-activation-on-unique-white-perception
#7
Dingcai Cao, Adam Chang, Shaoyan Gai
Current models of human color vision only consider cone inputs at photopic light levels, yet it is unclear whether the recently discovered melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) contribute to color perception. Using a lab-made five-primary photostimulator that can independently control the stimulations of rods, cones, and ipRGCs in human retina, we determined the observer's unique white perception, an equilibrium point for signals arising from the opponent mechanisms of color vision, under different levels of melanopsin activation...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29599657/phototransduction-in-retinal-ganglion-cells
#8
REVIEW
Peter B Detwiler
The mammalian retina contains a small number of retinal ganglion cells that express melanopsin, a retinal based visual pigment, and generate a depolarizing response to light in the absence of rod and cone driven synaptic input; hence they are referred to as intrinsically photosensitive retinal ganglion cells (ipRGCs). They have been shown to be comprised of a number of sub-types and to provide luminance information that participates primarily in a variety of non-imaging forming visual functions. Here I review what is currently known about the cascade of events that couple the photoisomerization of melanopsin to the opening of a non-selective cation channel...
March 2018: Yale Journal of Biology and Medicine
https://www.readbyqxmd.com/read/29573814/pupillary-responses-to-full-field-chromatic-stimuli-are-reduced-in-patients-with-early-stage-primary-open-angle-glaucoma
#9
Raymond P Najjar, Sourabh Sharma, Eray Atalay, Annadata V Rukmini, Christopher Sun, Jing Zhan Lock, Mani Baskaran, Shamira A Perera, Rahat Husain, Ecosse Lamoureux, Joshua J Gooley, Tin Aung, Dan Milea
PURPOSE: To evaluate the ability of chromatic pupillometry to reveal abnormal pupillary responses to light in patients with early-stage primary open-angle glaucoma (POAG) and to test whether the degree of pupillometric impairment correlates with structural hallmarks of optic nerve damage in the disease. DESIGN: Cross-sectional study. PARTICIPANTS: Forty-six patients with early-stage POAG (63.4±8.3 years, 63% male, 87% ethnic-Chinese) and 90 age-matched healthy controls (61...
March 21, 2018: Ophthalmology
https://www.readbyqxmd.com/read/29564797/functional-assessment-of-melanopsin-driven-light-responses-in-the-mouse-multielectrode-array-recordings
#10
Shi-Jun Weng, Jordan M Renna, Wei-Yi Chen, Xiong-Li Yang
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are a special subset of retinal output neurons capable of detecting and responding to light via a unique photopigment called melanopsin. Melanopsin activation is essential to a wide array of physiological functions, especially to those related to non-image-forming vision. Since ipRGCs only constitute a very small proportion of retinal ganglion cells, targeted recording of melanopsin-driven responses used to be a big challenge to vision researchers...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29564796/morphological-identification-of-melanopsin-expressing-retinal-ganglion-cell-subtypes-in-mice
#11
Seul Ki Lee, Tiffany M Schmidt
Melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) are a relatively recently discovered class of photoreceptor. ipRGCs can be subdivided into at least five subtypes (M1-M5), each of which has a distinct complement of morphological and physiological properties. ipRGC subtypes can be identified morphologically based on a combination of dendritic morphology and immunostaining for a cell-type specific marker. In this chapter, we describe methods for conclusively identifying each of the five ipRGC subtypes through a combination of patch clamp electrophysiology, Neurobiotin filling, visualization of ipRGC dendrites, and immunostaining for the marker SMI-32...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29564599/morphological-properties-of-medial-amygdala-projecting-retinal-ganglion-cells-in-the-mongolian-gerbil
#12
Liju Luan, Chaoran Ren, Wenyao Wang, Yan Nan, Jie Gao, Mingliang Pu
The amygdala is a limbic structure that is involved in many brain functions, including emotion, learning and memory. It has been reported that melanopsin-expressing retinal ganglion cells (ipRGCs) innervate the medial amygdala (MeA). However, whether conventional RGCs (cRGCs) project to the MeA remains unknown. The goal of this study was to determine if cRGCs project to the MeA and to determine the morphological properties of MeA-projecting RGCs (MeA-RGCs). Retrogradely labeled RGCs in whole-mount retinas were intracellularly injected to reveal their dendritic morphologies...
March 19, 2018: Science China. Life Sciences
https://www.readbyqxmd.com/read/29561501/the-iprgc-driven-pupil-response-with-light-exposure-refractive-error-and-sleep
#13
Kaleb S Abbott, Hope M Queener, Lisa A Ostrin
SIGNIFICANCE: We investigated links between the intrinsically photosensitive retinal ganglion cells, light exposure, refractive error, and sleep. Results showed that morning melatonin was associated with light exposure, with modest differences in sleep quality between myopes and emmetropes. Findings suggest a complex relationship between light exposure and these physiological processes. PURPOSE: Intrinsically photosensitive retinal ganglion cells (ipRGCs) signal environmental light, with pathways to the midbrain to control pupil size and circadian rhythm...
March 21, 2018: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/29472844/f-spondin-is-essential-for-maintaining-circadian-rhythms
#14
Gabriela L Carrillo, Jianmin Su, Aboozar Monavarfeshani, Michael A Fox
The suprachiasmatic nucleus (SCN) is the master pacemaker that drives circadian behaviors. SCN neurons have intrinsic, self-sustained rhythmicity that is governed by transcription-translation feedback loops. Intrinsic rhythms within the SCN do not match the day-night cycle and are therefore entrained by light-derived cues. Such cues are transmitted to the SCN by a class of intrinsically photosensitive retinal ganglion cells (ipRGCs). In the present study, we sought to identify how axons from ipRGCs target the SCN...
2018: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/29346496/melanopsin-system-dysfunction-in-smith-magenis-syndrome-patients
#15
Mirella Telles Salgueiro Barboni, Clarissa Bueno, Balázs Vince Nagy, Patrícia Lobo Maia, Kallene Summer Moreira Vidal, Rosana Cardoso Alves, Russel J Reiter, Fernanda Gaspar do Amaral, José Cipolla-Neto, Dora Fix Ventura
Purpose: Smith-Magenis syndrome (SMS) causes sleep disturbance that is related to an abnormal melatonin profile. It is not clear how the genomic disorder leads to a disturbed synchronization of the sleep/wake rhythm in SMS patients. To evaluate the integrity of the intrinsically photosensitive retinal ganglion cell (ipRGC)/melanopsin system, the transducers of the light-inhibitory effect on pineal melatonin synthesis, we recorded pupillary light responses (PLR) in SMS patients. Methods: Subjects were SMS patients (n = 5), with molecular diagnosis and melatonin levels measured for 24 hours and healthy controls (n = 4)...
January 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29304147/the-organization-of-melanopsin-immunoreactive-cells-in-microbat-retina
#16
Mi-Jin Jeong, Hang-Gu Kim, Chang-Jin Jeon
Intrinsically photosensitive retinal ganglion cells (ipRGCs) respond to light and play roles in non-image forming vision, such as circadian rhythms, pupil responses, and sleep regulation, or image forming vision, such as processing visual information and directing eye movements in response to visual clues. The purpose of the present study was to identify the distribution, types, and proportion of melanopsin-immunoreactive (IR) cells in the retina of a nocturnal animal, i.e., the microbat (Rhinolophus ferrumequinum)...
2018: PloS One
https://www.readbyqxmd.com/read/29249284/the-m5-cell-a-color-opponent-intrinsically-photosensitive-retinal-ganglion-cell
#17
Maureen E Stabio, Shai Sabbah, Lauren E Quattrochi, Marissa C Ilardi, P Michelle Fogerson, Megan L Leyrer, Min Tae Kim, Inkyu Kim, Matthew Schiel, Jordan M Renna, Kevin L Briggman, David M Berson
Intrinsically photosensitive retinal ganglion cells (ipRGCs) combine direct photosensitivity through melanopsin with synaptically mediated drive from classical photoreceptors through bipolar-cell input. Here, we sought to provide a fuller description of the least understood ipRGC type, the M5 cell, and discovered a distinctive functional characteristic-chromatic opponency (ultraviolet excitatory, green inhibitory). Serial electron microscopic reconstructions revealed that M5 cells receive selective UV-opsin drive from Type 9 cone bipolar cells but also mixed cone signals from bipolar Types 6, 7, and 8...
January 3, 2018: Neuron
https://www.readbyqxmd.com/read/29238991/distribution-and-diversity-of-intrinsically-photosensitive-retinal-ganglion-cells-in-tree-shrew
#18
Elizabeth N Johnson, Teleza Westbrook, Rod Shayesteh, Emily L Chen, Joseph W Schumacher, David Fitzpatrick, Greg D Field
Intrinsically photosensitive retinal ganglion cells (ipRGCs) mediate the pupillary light reflex, circadian entrainment, and may contribute to luminance and color perception. The diversity of ipRGCs varies from rodents to primates, suggesting differences in their contributions to retinal output. To further understand the variability in their organization and diversity across species, we used immunohistochemical methods to examine ipRGCs in tree shrew (Tupaia belangeri). Tree shrews share membership in the same clade, or evolutionary branch, as rodents and primates...
December 14, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/29149913/subadditive-responses-to-extremely-short-blue-and-green-pulsed-light-on-visual-evoked-potentials-pupillary-constriction-and-electroretinograms
#19
Soomin Lee, Yuria Uchiyama, Yoshihiro Shimomura, Tetsuo Katsuura
BACKGROUND: The simultaneous exposure to blue and green light was reported to result in less melatonin suppression than monochromatic exposure to blue or green light. Here, we conducted an experiment using extremely short blue- and green-pulsed light to examine their visual and nonvisual effects on visual evoked potentials (VEPs), pupillary constriction, electroretinograms (ERGs), and subjective evaluations. METHODS: Twelve adult male subjects were exposed to three light conditions: blue-pulsed light (2...
November 17, 2017: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/29102785/melanopsin-expressing-retinal-ganglion-cells-are-relatively-resistant-to-excitotoxicity-induced-by-n-methyl-d-aspartate
#20
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
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