| Systemic thyroid hormone is necessary and sufficient to induce ultraviolet-sensitive cone loss in the juvenile rainbow trout retina. | |
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MedLine Citation:
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PMID: 20086135 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Rainbow trout possess ultraviolet-sensitive (UVS) cones in their retina that degenerate naturally during development. This phenomenon can be induced with exogenous thyroxine [T4, a thyroid hormone (TH)] treatment. However, the previous T4 exposure experiments employed static water immersion; a method that could introduce confounding stress effects on the fish. Because of this, it was uncertain if T4 alone was sufficient to induce retinal changes or if stress-related hormones were also necessary to initiate this process. Furthermore, it was unclear whether endogenous T4 was the factor responsible for initiating natural UVS cone loss during development. The current study examined the role of systemic T4 on the juvenile rainbow trout retina using a slow-release implant. Exogenous T4 treatment resulted in SWS1 opsin downregulation and UVS cone loss after four weeks of exposure, signifying that T4 is sufficient to induce this process. Blocking endogenous T4 production with propylthiouracil (PTU, an anti-thyroid agent) attenuated SWS1 downregulation and UVS cone loss in the retina of naturally developing rainbow trout, suggesting that endogenous T4 is necessary to initiate retinal remodelling during development. Quantitative real-time RT-PCR analysis demonstrated that several TH-regulating components are expressed in the trout retina, and that expression levels of the TH receptor isoform TRbeta and the type 2 deiodinase (D2) change with T4 treatment. This suggests that T4 may act directly on the retina to induce UVS cone loss. Taken together, these results demonstrate that systemic TH is necessary and sufficient to induce SWS1 opsin downregulation and UVS cone loss in the retina of juvenile rainbow trout. |
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Authors:
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J C Raine; A B Coffin; C W Hawryshyn |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of experimental biology Volume: 213 ISSN: 1477-9145 ISO Abbreviation: J. Exp. Biol. Publication Date: 2010 Feb |
Date Detail:
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Created Date: 2010-01-20 Completed Date: 2010-03-16 Revised Date: 2010-05-19 |
Medline Journal Info:
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Nlm Unique ID: 0243705 Medline TA: J Exp Biol Country: England |
Other Details:
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Languages: eng Pagination: 493-501 Citation Subset: IM |
Affiliation:
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Department of Biology, Queen's University, Kingston, Ontario, Canada, K7L 3N6. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Aging
/
drug effects,
metabolism*,
radiation effects Animals Fish Proteins / genetics, metabolism Gene Expression Regulation / drug effects, radiation effects Immunohistochemistry Oncorhynchus mykiss / anatomy & histology, blood, metabolism* Propylthiouracil / administration & dosage, pharmacology Retinal Cone Photoreceptor Cells / drug effects, metabolism, pathology*, radiation effects* Reverse Transcriptase Polymerase Chain Reaction Thyroid Hormones / metabolism* Thyroxine / administration & dosage, blood, pharmacology Ultraviolet Rays* |
| Chemical | |
Reg. No./Substance:
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0/Fish Proteins; 0/Thyroid Hormones; 51-52-5/Propylthiouracil; 7488-70-2/Thyroxine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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