title: Noninvasive multiphoton fluorescence microscopy resolves retinol and retinal condensation products in mouse eyes.
abstract: Multiphoton excitation fluorescence microscopy (MPM) can image certain molecular processes in vivo. In the eye, fluorescent retinyl esters in subcellular structures called retinosomes mediate regeneration of the visual chromophore, 11-cis-retinal, by the visual cycle. But harmful fluorescent condensation products of retinoids also occur in the retina. We report that in wild-type mice, excitation with a wavelength of ∼730 nm identified retinosomes in the retinal pigment epithelium, and excitation with a wavelength of ∼910 nm revealed at least one additional retinal fluorophore. The latter fluorescence was absent in eyes of genetically modified mice lacking a functional visual cycle, but accentuated in eyes of older wild-type mice and mice with defective clearance of all-trans-retinal, an intermediate in the visual cycle. MPM, a noninvasive imaging modality that facilitates concurrent monitoring of retinosomes along with potentially harmful products in aging eyes, has the potential to detect early molecular changes due to age-related macular degeneration and other defects in retinoid metabolism.
authors.affiliation: Polgenix, Cleveland, Ohio, USA. gpalczewska@polgenixinc.com
authors.forename: Grazyna
authors.initials: G
authors.lastname: Palczewska
authors.forename: Tadao
authors.initials: T
authors.lastname: Maeda
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Imanishi
authors.forename: Wenyu
authors.initials: W
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: David R
authors.initials: DR
authors.lastname: Williams
authors.forename: David W
authors.initials: DW
authors.lastname: Piston
authors.forename: Akiko
authors.initials: A
authors.lastname: Maeda
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
mesh_terms: D000818:Animals; D005123:Eye / Q000166:cytology*; D008074:Lipoproteins / Q000032:analysis* / Q000648:ultrastructure; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D011726:Pyridinium Compounds / Q000032:analysis*; D055213:Retinal Pigment Epithelium / Q000737:chemistry*; D012176:Retinoids / Q000032:analysis*; D012177:Retinol-Binding Proteins / Q000032:analysis* / Q000648:ultrastructure; D000084562:Retinyl Esters; D014801:Vitamin A / Q000032:analysis*
chemical_list: C112040:A2-E (N-retinylidene-N-retinylethanolamine); D008074:Lipoproteins; D011726:Pyridinium Compounds; D012176:Retinoids; D012177:Retinol-Binding Proteins; D000084562:Retinyl Esters; C022081:retinyl ester lipoprotein complex; D014801:Vitamin A