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Journal of Psychiatric Research Aug 1971
Review
Topics: Animals; Arthropods; Dinitrophenols; Electrophysiology; Kinetics; Light; Models, Chemical; Models, Neurological; Photochemistry; Photoreceptor Cells; Retinal Pigments; Temperature
PubMed: 4939378
DOI: 10.1016/0022-3956(71)90025-2 -
Journal of Neuropathology and... Sep 1982Neurotoxic and gliotoxic effects of glutamate were studied in isolated chick embryo retinas of various ages. Employing a short-term incubation system, we found that...
Neurotoxic and gliotoxic effects of glutamate were studied in isolated chick embryo retinas of various ages. Employing a short-term incubation system, we found that initial cellular changes in retinas from 15- and 21-day chick embryos were localized to glial Müller cells as previously shown in retinas from 12-day embryos. In the older retinas, however, an additional selective lesion was consistently found in the presumptive photoreceptor cells. Similar photoreceptor damage was not seen in 12-day retinas, even after treatment with relatively high glutamate doses. Autoradiographic uptake of tritiated glutamate in retinas at 12 and 14 days was localized to the glial Müller cells; in the 14-day retinas, however, there was also uptake of the labeled amino acid into the developing inner segments. Uptake of tritiated glutamate in retinas at younger (8-day) and older (21-day) ages did not show any obvious localization of the label.
Topics: Age Factors; Animals; Chick Embryo; Glutamates; In Vitro Techniques; Photoreceptor Cells; Retina
PubMed: 7108566
DOI: 10.1097/00005072-198209000-00005 -
Current Opinion in Neurobiology Aug 1992The primary feedback control apparatus in the outer retina is the sign-inverting feedback synapse between horizontal cells and cones. In many lower vertebrates... (Review)
Review
The primary feedback control apparatus in the outer retina is the sign-inverting feedback synapse between horizontal cells and cones. In many lower vertebrates horizontal cells release GABA in darkness, which opens Cl- channels in cones. Input-output relations of the feedback synapse reveal that the synaptic gain is light-dependent with the highest negative gain near the dark horizontal cell potential. The horizontal cell-cone feedback synapse improves the reliability of the photoreceptor output synapses. It also modulates the dynamic range and mediates color opponency and surround responses in second-order retinal neurons.
Topics: Animals; Feedback; Humans; Photoreceptor Cells; Retina
PubMed: 1525544
DOI: 10.1016/0959-4388(92)90181-j -
The American Journal of Anatomy Jun 1985The fine structure and arrangement of the photoreceptor cells of the archerfish (Toxotes jaculatrix) have been studied by electron microscopy.Rods, twin cones, and...
The fine structure and arrangement of the photoreceptor cells of the archerfish (Toxotes jaculatrix) have been studied by electron microscopy.Rods, twin cones, and single cones are present. In the light-adapted state, the rods are very tall cells reaching almost to the base of the retinal epithelial cells. The outer segment is composed of membranous discs of uniform diameter displaying a single incisure. The rod inner segment displays a distal small ellipsoid and an extremely thin myoid region. The nuclei of rods are electrondense,and the synaptic spherule displays two or three invaginated sites. The single cone is similar to the individual members of a twin cone and displays a tapering outer segment and accompanying accessory outer segment. The wider cone inner segment contains a large, centrally located ellipsoid and a peripheral region rich in endoplasmic reticulum, polysomes, and microfilaments.Twin cones display subsurface cisternae along their entire contiguous surfaces.The cone nuclei are large and vesicular and located vitread to the external limiting membrane. The synaptic pedicle of cones is larger and more electronlucent and contains more invaginated "ribbon" synaptic sites (ten to 12) than do rods. In addition, small "coated" invaginations and larger synaptic vesiclefilled processes are also seen within cone pedicles. In the light-adapted state the cone photoreceptors are arranged in a repeating square mosaic pattern with one single cone surrounded by four twin cones.
Topics: Animals; Endoplasmic Reticulum; Microscopy, Electron; Perciformes; Photoreceptor Cells; Photoreceptor Cells, Vertebrate; Retina; Retinal Cone Photoreceptor Cells; Retinal Photoreceptor Cell Inner Segment; Retinal Rod Photoreceptor Cells
PubMed: 20726114
DOI: 10.1002/aja.1001730203 -
Cell Structure and Function Oct 1991L-Glutamate, a putative photoreceptor cell neurotransmitter, causes thinning of the inner layers of the retina and has been used for preparing biologically fractionated... (Comparative Study)
Comparative Study
L-Glutamate, a putative photoreceptor cell neurotransmitter, causes thinning of the inner layers of the retina and has been used for preparing biologically fractionated photoreceptor cells. However, it is possible that absence of the inner retinal layers may affect the remaining retina, and/or glutamate may directly affect photoreceptor cells. We evaluated quantitatively the effects of L-glutamate on the developing photoreceptor cells by measuring the rod photoreceptor cell-specific protein, opsin. We purified rat rhodopsin and used it as the standard for measuring opsin content of rat retinas with competitive enzyme-linked immunosorbent assay. Various concentrations of glutamate were injected into 7-day-old rats, and the effects of the amino acid concentration on opsin expression were determined on postnatal day 14. Inner layers of the retina degenerated when 10 microliters or 15 microliters of 2.4 M glutamate/gram body weight was administered subcutaneously. Opsin content of these glutamate-treated retinas decreased significantly compared with control retinas. We administered glutamate to rats at various stages of development and determined the effects by light microscopy on postnatal day 14. The administration of glutamate resulted in no degeneration of the inner retina if injected on postnatal day 1 or 2, degeneration of the inner retina between day 3 to 7, and again, no degeneration after postnatal day 13. Opsin content decreased significantly when glutamate was administered between postnatal day 1 to 7, but not after day 13, the day the blood-retinal barrier seems to reach maturity. Our findings indicate that systemic administration of L-glutamate affects the expression of opsin in the developing rod photoreceptor cells.
Topics: Animals; Animals, Newborn; Dose-Response Relationship, Drug; Eye Proteins; Photoreceptor Cells; Rats; Rats, Inbred Strains; Retina; Rod Opsins; Sodium Glutamate
PubMed: 1837498
DOI: 10.1247/csf.16.399 -
Current Biology : CB Dec 1995
Review
Topics: Cryptochromes; Drosophila Proteins; Eye Proteins; Flavoproteins; Genes, Plant; Light; Photoreceptor Cells; Photoreceptor Cells, Invertebrate; Plant Proteins; Receptors, G-Protein-Coupled; Signal Transduction
PubMed: 8749382
DOI: 10.1016/s0960-9822(95)00267-3 -
Vision Research Apr 1968
Topics: Amphibians; Anatomy, Comparative; Animals; Biological Evolution; Birds; Lizards; Marsupialia; Microscopy, Electron; Photoreceptor Cells; Reptiles; Snakes; Terminology as Topic
PubMed: 5760533
DOI: 10.1016/0042-6989(68)90117-x -
Investigative Ophthalmology & Visual... Feb 1978
Topics: Animals; Circadian Rhythm; Darkness; Humans; Light; Photoreceptor Cells; Regeneration
PubMed: 624608
DOI: No ID Found -
Nature Nov 1993Retinal photoreceptors are noisy. They generate discrete electrical events in the dark indistinguishable from those evoked by light and thereby limit visual sensitivity...
Retinal photoreceptors are noisy. They generate discrete electrical events in the dark indistinguishable from those evoked by light and thereby limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature-dependent and have been attributed to thermal isomerizations of the vitamin A chromophore of rhodopsin, the light-sensitive molecule in photoreceptors. But thermal generation of dark events in both vertebrate and invertebrate photoreceptors requires activation energies in the range of 23 to 27 kcal mol-1, which are significantly less than the energy barrier of 45 kcal mol-1, for photoisomerization of the chromophore of native rhodopsin. We propose that photoreceptor noise results from the thermal isomerization of a relatively unstable form of rhodopsin, one in which the Schiff-base linkage between the chromophore and protein is unprotonated. This molecular mechanism is supported by both theoretical calculations of the properties of rhodopsin and experimental measurements of the properties of photoreceptor noise.
Topics: Animals; Circadian Rhythm; Horseshoe Crabs; Hydrogen-Ion Concentration; In Vitro Techniques; Isomerism; Photochemistry; Photoreceptor Cells; Photoreceptor Cells, Invertebrate; Rhodopsin; Schiff Bases; Thermodynamics
PubMed: 8232538
DOI: 10.1038/366064a0 -
Nature Feb 1980Electrical responses of cone photoreceptors in the retina of the freshwater turtle have been characterised for flashes and steps of light in darkness and in the presence...
Electrical responses of cone photoreceptors in the retina of the freshwater turtle have been characterised for flashes and steps of light in darkness and in the presence of background light. These intracellular measurements have been combined with the behavioural increment threshold curve to yield an estimate of 5-10 muV for the signal developed in a cone when the turtle can just detect an increment flash. The signal developed when the cones under the stimulus image are dark-adapted is of interest, for its measurement would help to explain how known physiological processes subserve visual detection for a variety of photic conditions. The effective quantal absorption of dark-adapted, red-sensitive cones of Pseudemys scripta elegans for a stimulus that the turtle can just detect is reported here. By combining this result with previous electrical measurements on red-sensitive cones of this species, an estimate of 35-70 muV is obtained for the signal developed in a dark-adapted cone at behavioural threshold. This larger signal required for detection of a flash in darkness is of particular interest in view of the recent observation that the intrinsic noise of turtle cones in darkness is larger than that of illuminated cones.
Topics: Animals; Behavior, Animal; Dark Adaptation; Dose-Response Relationship, Radiation; Light; Photoreceptor Cells; Turtles
PubMed: 7360231
DOI: 10.1038/283860a0