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Martin Glösmann, Reinhard Ertl, Tanja Himmel, Stefan Kummer, Ursula Reichart; Thyroid Hormone Regulates mRNA Expression of the Vitamin D Receptor in Mouse Photoreceptors. Invest. Ophthalmol. Vis. Sci. 2016;57(12):564.
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© ARVO (1962-2015); The Authors (2016-present)
We found earlier that the 1,25(OH)2 vitamin D3 receptor (VDR) is present in the ganglion cell and inner nuclear layer of the adult mouse retina (Glösmann M, et al. IOVS 2011; 52: ARVO E-Abstract 924). This study sought to evaluate whether VDR expression extends to photoreceptors and is thyroid hormone (TH) dependent.
Adult male C57BL/6J mice were rendered hypothyroid using methimazole (MMI), sodium perchlorate, and low-iodine diet. Control animals received water without MMI/perchlorate. After 8 weeks, animals were either sacrificed or received a single dose of 200 ng triiodothyronine (T3)/g b.w. intraperitoneally and were sacrificed 6 h, 24 h, and 48 h post injection. Photoreceptors were isolated using laser capture microdissection (LCM) and mRNA levels measured by microarray analysis and quantitative real time PCR (RT-qPCR). Monoclonal VDR antibody D6 and indirect immunofluorescence were used on frozen and paraffin-embedded sections of retinas to localize VDR expression in photoreceptors in C57BL/6J mice.
VDR-D6 immunofluorescence signal was detected in nuclei and cytoplasm of both rods and cones. Microarray data analysis showed that VDR expression did not significantly differ between dorsal and ventral photoreceptors in control retinas and was not affected by hypothyroid treatment. Six to 24 h after injection of T3, VDR mRNA levels in photoreceptors were found up to three-fold increased compared to hypothyroid and control mice. RT-qPCR analysis established a 7-9 fold upregulation of VDR mRNA in samples of entire retinas 6-24 h after T3 injection.
VDR is expressed in all retinal neurons including photoreceptors. TH, directly or indirectly, is a positive regulator of VDR expression.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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