Altered Expression of Aquaporin 1 in a Mutant Rat With Ocular Developmental Abnormalties

Abstract

Abstract: : Purpose: A spontaneous mutation (Nuc1) in the Sprague–Dawley rat produces a phenotype of eye–specific abnormalities involving various ocular tissues. Microarray analysis of retina/ciliary body preparations revealed a marked decrease in Aquaporin 1 message. This study was undertaken to confirm that finding and to investigate its possible significance to the Nuc1 phenotype. Methods: Microarry studies utilized the Affymatrix oligonucleotide system. Real–time PCR was used to confirm the microarray result. Immunohistochemistry with specific antibodies to Aquaporin 1 was used to localize the protein in cryosections of Nuc1 and age–matched wildtype rat eyes. Results: Microarray analysis of retina/ciliary body samples from 25 day old rats revealed a significant decrease in Aquaporin 1 gene expression in the Nuc1 homozygous rat relative to wildtype littermates. This finding was confirmed by Real–time PCR analysis. Immunohistochemistry indicated that the Aquaporin 1 reactivity was predominantly in the ciliary body and that it was markedly lower in the Nuc1 homozygote as compared to the wildtype. Interestingly, in younger animals (9 days), the mutant appeared to have relatively normal immunofluorescence for Aquaporin 1. The Nuc1 animals also exhibited a shallowing of the anterior chamber and in some cases apposition of the iris and cornea, which could result from reduced aqueous humor production due to decreased Aquaporin 1 in the ciliary body. Conclusions: Decreased Aquaporin 1 in the ciliary body of Nuc1 rats may play an important role in some phenotypic characteristics of this animal model.

Keywords: ciliary body • gene/expression • pathology: experimental