| First Author | Saari JC | Year | 2002 |
| Journal | Invest Ophthalmol Vis Sci | Volume | 43 |
| Issue | 6 | Pages | 1730-5 |
| PubMed ID | 12036972 | Mgi Jnum | J:76816 |
| Mgi Id | MGI:2180394 | Citation | Saari JC, et al. (2002) Analysis of the visual cycle in cellular retinol-binding protein type I (CRBPI) knockout mice. Invest Ophthalmol Vis Sci 43(6):1730-5 |
| abstractText | PURPOSE: To determine whether the visual cycle is affected in mice without a functional gene for cellular retinol-binding protein type I (CRBPI(-/-) mice). METHODS: Visual-cycle retinoids and rhodopsin levels were analyzed in eyes of dark adapted (DA) CRBPI(-/-) and wild-type (wt) mice before and during recovery from a flash. The rate of dark adaptation was analyzed using electroretinography (ERG). RESULTS: all-trans-retinyl esters were reduced to approximately 33% of wt levels in DA CRBPI(-/-) mice. Recovery from a flash in wt mice produced transient accumulations of all-trans-retinal and all-trans-retinyl ester, as the pulse of retinoid produced by the flash traversed the visual cycle. In CRBPI(-/-) mice, all-trans-retinal accumulated transiently, as in wt mice. However, all-trans-retinol also accumulated transiently in the neural retina, and the transient increase in all-trans-retinyl ester of the wt was reduced. Rates of 11-cis-retinal and rhodopsin formation were comparable in wt and CRBPI(-/-) mice. Dark adaptation was delayed by a factor of approximately two. CONCLUSIONS: The accumulation of all-trans-retinol in neural retina, in the absence of CRBPI and the reduced amount of retinyl esters in the RPE suggest that the binding protein participates in a process that drives diffusion of all-trans-retinol from photoreceptor cells to RPE, perhaps by delivering vitamin A to lecithin-retinol acyltransferase (LRAT) for esterification. Because the perturbation occurred upstream of a slow step of the visual cycle, there was no major impairment of the rate of visual pigment regeneration. |
