Retinal serotonin, eye growth and myopia development in chick

George, Abigail L., Schmid, Katrina L., & Pow, David V. (2005) Retinal serotonin, eye growth and myopia development in chick. Experimental Eye Research, 81(5), pp. 616-625.

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Abstract

Myopia (short-sightedness) is a visual problem associated with excessive eye growth and vitreous chamber expansion. Within the eye serotonin (5-hydroxytryptamine, 5-HT) appears to have a variety of effects, it alters retinal amacrine cell processing, increases intraocular pressure, constricts ocular blood vessels, and is also mitogenic. This study sought to determine the role of the retinal serotonin system in eye growth regulation. Myopia was produced in 7-day-old chicks using -15 D spectacle lenses (LIM) and form deprivation (FDM). The effect on LIM and FDM of daily intravitreal injections of a combination of 5-HT receptor antagonists (1, 10, 50 microM), 5-HT(2) selective antagonist (Mianserin 0.5, 20 microM) or 5-HT (1, 10, 50 microM) were assessed. Counts were performed of serotonin and tyrosine hydroxylase positive neurons and the relative density used to account for areal changes due to eye growth. The effect of LIM and lens-induced hyperopia (LIH) on the numbers of 5-HT-containing amacrine cells in the retina were then determined. The combination of 5-HT receptor antagonists inhibited LIM by approximately half (1 microM RE: -7.12+/-1.0 D, AL: 0.38+/-0.06 mm vs. saline RE: -13.19+/-0.65 D, AL: 0.64+/-0.03 mm. RE: p<0.01, AL: p<0.01), whereas FDM was not affected (1 microM RE: -8.88+/-1.10 D vs. saline RE: -9.28+/-1.38 D). The selective antagonist was slightly less effective at inhibiting LIM (0.5 microM RE: -9.02+/-1.01 D). These data suggest that serotonin has a stimulatory role in LIM, although high doses of serotonin were inhibitory (1 microM RE: -9.30+/-1.34 D). 5-HT immunoreactivity was localised to a subset of amacrine cell bodies in the inner nuclear layer of the retina, and to two synaptic strata in the inner plexiform layer. LIM eyes had increased numbers of 5-HT-containing amacrine cells in the central retina (12.5%). Collectively, these results suggest that manipulations to the serotonin system can alter the eye growth process but the role of this transmitter system within this process remains unclear.

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ID Code: 4277
Item Type: Journal Article
Refereed: Yes
Additional Information: For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: schmid.k@qut.edu.au
Keywords: Eye/, growth & development, Myopia/, metabolism, Myopia/, physiopathology, Serotonin/, pharmacology, Amacrine Cells/chemistry, Amacrine Cells/drug effects, Amacrine Cells/metabolism, Animals, Cell Count, Chickens, Comparative Study, Eye/drug effects, Eye/metabolism, Eyeglasses, Injections, Male, Mianserin/pharmacology, Models, Animal, Refraction, Ocular, Sensory Deprivation, Serotonin/analysis, Serotonin/metabolism, Serotonin Antagonists/pharmacology
DOI: 10.1016/j.exer.2005.03.021
ISSN: 0014-4835
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2005 Elsevier
Deposited On: 14 Jun 2006 00:00
Last Modified: 29 Feb 2012 13:15

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