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Manganese‐enhanced MRI (MEMRI) via topical loading of Mn 2+ significantly impairs mouse visual acuity: a comparison with intravitreal injection
Author(s) -
Lin TsenHsuan,
Chiang ChiaWen,
Trinkaus Kathryn,
Spees William M.,
Sun Peng,
Song ShengKwei
Publication year - 2014
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3073
Subject(s) - retina , ophthalmology , optic nerve , medicine , retinal , retinal ganglion cell , h&e stain , in vivo , diffusion mri , visual acuity , biomedical engineering , chemistry , pathology , magnetic resonance imaging , immunohistochemistry , neuroscience , biology , radiology , microbiology and biotechnology
Manganese‐enhanced MRI (MEMRI) with topical loading of MnCl 2 provides optic nerve enhancement comparable to that seen by intravitreal injection. However, the impact of this novel and non‐invasive Mn 2+ loading method on visual function requires further assessments. The objective of this study is to determine the optimal topical Mn 2+ loading dosage for MEMRI and to assess visual function after MnCl 2 loading. Intravitreal administration was performed to compare the two approaches of MnCl 2 loading. Twenty‐four hours after topical loading of 0, 0.5, 0.75, and 1 M MnCl 2 , T 1 ‐weighted, T2‐weighted, diffusion tensor imaging and visual acuity (VA) assessments were performed to determine the best topical loading dosage for MEMRI measurements and to assess the integrity of retinas and optic nerves. Mice were perfusion fixed immediately after in vivo experiments for hematoxylin and eosin and immunohistochemistry staining. Topical loading of 1 M MnCl 2 damaged the retinal photoreceptor layer with no detectable damage to retina ganglion cell layers or prechiasmatic optic nerves. For the topical loading, 0.75 M MnCl 2 was required to see sufficient enhancement of the optic nerve. At this concentration the visual function was significantly affected, followed by a slow recovery. Intravitreal injection (0.25 μL of 0.2 M MnCl 2 ) slightly affected VA, with full recovery a day later. To conclude, intravitreal MnCl 2 injection provides more reproducible results with less adverse side‐effects than topical loading. Copyright © 2014 John Wiley & Sons, Ltd.