Retinal and optic nerve serotonin and retinal degeneration as influenced by photoperiod.
TL;DR: The results demonstrate that serotonin is influenced by photoperiod fluctuations and suggest that the biogenic amine might be related to light-induced changes in neuroendocrine function.
About: This article is published in Experimental Neurology.The article was published on 1970-05-01. It has received 93 citations till now. The article focuses on the topics: Retina & Optic nerve.
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TL;DR: The National Academy of Sciences founded The National Academies Press (NAP) with the goal of publishing reports of all four national academies as mentioned in this paper, which publishes more than 200 books from the fields of science, engineering and medicine and offers more than 4000 titles in PDF on its website.
Abstract: The National Academy of Sciences founded The National Academies Press (NAP) with the goal of publishing reports of all four national academies. Annually, NAP publishes more than 200 books from the fields of science, engineering and medicine and offers more than 4000 titles in PDF on its website (http://www.nap.edu/) free of charge.
1,241 citations
Cites background from "Retinal and optic nerve serotonin a..."
...7 lx (6-18 ft-candles)—continuously for 4 days can cause degenerative retinal changes (Anderson et al., 1972; O'Steen, 1970; Williams, 1989)....
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TL;DR: The evidence that solar radiation is responsible for some of the deteriorative changes that lead to age-related macular degeneration is examined in this review.
398 citations
TL;DR: This work has suggested that blue light may play a role in the pathogenesis of age-related macular degeneration, and laboratory studies have suggested that photochemical damage includes oxidative events.
350 citations
TL;DR: It is suggested that retinal damage may be produced by such common light sources as room lighting, phototherapy techniques, ophthalmoscopes and fundus cameras.
249 citations
TL;DR: It is concluded that the high level of ambient illumination commonly found in the hospital nursery may be one factor contributing to retinopathy of prematurity and that safety standards with regard to current lighting practices should be reassessed.
Abstract: The preterm infant is subjected to prolonged exposure to ambient nursery illumination at levels that have been found to produce retinal damage in animals. We prospectively investigated the effect of exposure to light in two intensive care nurseries by comparing the incidence of retinopathy of prematurity among 74 infants from the standard bright nursery environment (median light level, 60 foot-candles [ftc]) with the incidence among 154 infants of similar birth weight for whom the light levels were reduced (median, 25 ftc). There was a higher incidence of retinopathy of prematurity in the group of infants who had been exposed to the brighter nursery lights, particularly in those with birth weights below 1000 g (86 per cent vs. 54 per cent, P<0.01 by chi-square test). We conclude that the high level of ambient illumination commonly found in the hospital nursery may be one factor contributing to retinopathy of prematurity and that safety standards with regard to current lighting practices should be...
219 citations
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TL;DR: The retina of laboratory rats is affected irreversibly by intense light applied for less than 1 hour or for up to 2 days depending upon experimental conditions, and the action spectrum of the daviaging effect approximated that of visual excitation as measured by the ERG.
Abstract: The retina of laboratory rats is affected irreversibly by intense light applied for less than 1 hour or for up to 2 days depending upon experimental conditions. Exposure of unanesthetized and unrestrained animals was in chambers surrounded by a green filter and circular fluorescent lamps of a nominal brightness of 2,040 footlamberts. Eyes of anesthetized animals were exposed diffusely to either the light from a 100 to. zirconium arc passing through filters or monochromatic light of various icavelengths. Irreversible reduction in ERG amplitudes and degeneration of visual cells and pigment epithelium indicated the severity of the light damage. The effect was very dependent upon the body (eye) temperature during exposure. Hyperthermia greatly accelerated and intensified the damaging action of light and for this reason most experiments reported in this paper were performed at a high body temperature. At a body temperature around 104° F. severe damage teas produced with exposures to 5 to 10 iiw per square centimeter retina for 1 hour. The minimal damaging dose at a high temperature was estimated to be about 1 ixw per square centimeter. The action spectrum~of the daviaging effect approximated that of visual excitation as measured by the ERG. Hooded (pigmented) animals were no more affected than albinos of different strains. Recovery in the dark from a just subliminally damaging dose of light at a high body temperature required about 24 hours and was preceded by a period of time during ichich the retina was "sensitized" to an additional dose. During or following exposure to light at a high body temperature visual cell and pigmentepithelial_damage developedTabout simultaneouslu and was first indicated bit pyknosis Trncl cell swelling followed rapidly by the dissolution of nuclei and cytoplasm. The crucial reaction in producing the damage is considered a "dark-reaction" initiated by light of an -inte7isiiTj_ which bleaches measurably rhodopsin. Hypotheses on the reaction sequence which 'leads to damage are briefly discussed.
1,121 citations
TL;DR: This work has shown that there is a ditirnal cycle in the enzymatic synthesis of melatonin and that this cycle is re,ulated by environmental lihltin.
375 citations
201 citations
TL;DR: It is concluded that the active depressants either block the access of the excitatory transmitter to subsynaptic receptors or prevent the release of the transmitter from optic nerve terminals.
Abstract: Indoles related to 5-hydroxytryptamine, lysergic acid derivatives, phenethylamine derivatives and some other compounds have been applied electrophoretically to the neurones of the lateral geniculate nucleus of the cat anaesthetized with pentobarbitone sodium. Many of these compounds, particularly 4-, 5- and 7-hydroxytryptamine and ergometrine, depress the orthodromic excitation of the neurones by volleys in optic nerve fibres, but do not affect antidromic excitation by volleys in the optic radiation or chemical excitation by L-glutamic acid. It is concluded that the active depressants either block the access of the excitatory transmitter to subsynaptic receptors or prevent the release of the transmitter from optic nerve terminals. The structure-activity relationships of the depressant substances are discussed.
184 citations
TL;DR: A light microscopic survey was made of the uptake and turnover of 5‐HT, synthesized in vivo from its administered tritium‐labelled precursor, 5‐hydroxytryptophan (5‐HTP).
Abstract: 1. A technique for the radioautographic identification, localization, and study of the turnover of cellular depots of 5-hydroxytryptamine (5-HT) has been evaluated. A light microscopic survey was made of the uptake and turnover of 5-HT, synthesized in vivo from its administered tritium-labelled precursor, 5-hydroxytryptophan (5-HTP).2. 5-HT was taken up rapidly and retained for long periods of time by adrenal medullary chromaffin cells, gastric enterochromaffin cells, blood platelets, thyroid parafollicular cells, beta cells of pancreatic islets, mast cells, and septal cells of the lung. Reticulo-endothelial cells of liver and spleen took up radioactive 5-HT more slowly but also retained it for days.3. Specific uptake, and a rapid turnover of radioactive 5-HT, was found in pancreatic exocrine cells, neurones of the superior cervical ganglion, terminal axons of gastro-intestinal myenteric plexus, carotid body cells, and pinealocytes.4. A supranuclear localization of radioactive 5-HT in renal proximal tubular cells may represent tubular secretion of 5-HT.5. The localization of 5-HT by radioautography generally corresponds to that found by formaldehyde-induced fluorescence. It makes possible the study of 5-HT turnover and is capable of greater resolution than the fluorescence technique. Freeze-drying may also be avoided.
177 citations