Cholinergic amacrine cells are not required for the progression and atropine-mediated suppression of form-deprivation myopia
| Autor: | Andy J. Fischer, William K. Stell, Pat Miethke, Ian G. Morgan |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Atropine
Male medicine.medical_specialty genetic structures Cell Survival Aziridines DNA Fragmentation Muscarinic Antagonists Biology Retina Choline Choline O-Acetyltransferase chemistry.chemical_compound Internal medicine Muscarinic acetylcholine receptor Myopia medicine Animals Cholinergic neuron Neurotransmitter Molecular Biology Toxins Biological Acetylcholine receptor General Neuroscience Quisqualic Acid Choline acetyltransferase eye diseases Form Perception Endocrinology medicine.anatomical_structure chemistry Depression Chemical Cholinergic sense organs Neurology (clinical) Chickens Acetylcholine Developmental Biology medicine.drug |
| Zdroj: | Brain Research. 794:48-60 |
| ISSN: | 0006-8993 |
| DOI: | 10.1016/s0006-8993(98)00188-7 |
| Popis: | Muscarinic cholinergic pathways have been implicated in the visual control of ocular growth. However, the source(s) of acetylcholine and the tissue(s) which regulate ocular growth via muscarinic acetylcholine receptors (mAChRs) remain unknown. We sought to determine whether retinal sources of acetylcholine and mAChRs contribute to visually guided ocular growth in the chick. Cholinergic amacrine cells were ablated by intraocular injections of either ethylcholine mustard aziridinium ion (ECMA; a selective cholinotoxin) or quisqualic acid (QA; an excitotoxin that destroys many amacrine cells, including those that release acetylcholine). Disruption of cholinergic pathways was assessed immunocytochemically with antibodies to the acetylcholine-synthesizing enzyme choline acetyltransferase (ChAT) and three different isoforms of mAChR, and by biochemical assay for ChAT activity. ECMA (25 nmol) destroyed two of the four subtypes of cholinergic amacrine cells and attenuated retinal ChAT activity, but left retinal mAChR-immunoreactivity intact. QA (200 nmol) destroyed the majority of all four subtypes of cholinergic amacrine cells, and ablated most mAChR-immunoreactivity and ChAT activity in the retina. ECMA and QA had no apparent effect on mAChRs or cholinergic fibres in the choroid, only marginally reduced choroidal ChAT activity, and had little effect on ChAT activity in the anterior segment. Toxin-treated eyes remained emmetropic and responded to form-deprivation by growing excessively and becoming myopic. Furthermore, daily intravitreal injection of 40 microg atropine for 6 days into form-deprived toxin-treated eyes completely prevented ocular elongation and myopia. We conclude that neither cholinergic amacrine cells nor mAChRs in the retina are required for visual regulation of ocular growth, and that atropine may exert its growth-suppressing influence by acting upon extraretinal mAChRs, possibly in the choroid, retinal pigmented epithelium, or sclera. |
| Databáze: | OpenAIRE |
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