Lack of Glial Intermediate Filaments Affects Vascular Development and Retinal Function

Abstract

Purpose: : The expression of the intermediate filaments (IFs) glial fibrilary acidic protein (GAFP) and vimentin is tightly regulated during development and changes in expression are also noted following injury and in the course of various pathologic states. The purpose of the present study was to examine the intact retinas of mice lacking these IFs.

Methods: : The expression of several neuronal and glial markers was analyzed by immunohistochemistry and Western Blot in retinas obtained from GFAP and vimentin knockout (GV dKO) mice of different ages. The retinal vasculature was examined in whole mount preparations and by scanning laser ophthalmoscopy (SLO). Retinal function was assessed by electroretinography (ERG).

Results: : No differences were found in the distribution or level of expression of any of the neuronal or glial markers analyzed. ERG recordings showed a significant increase of scotopic b-wave amplitudes in GV dKO, compared to congenic controls at 3, 5 and 8 weeks of age. SLO analysis revealed the presence of a significant number of persistent vitreal vessels together with residues of the pupillary membrane in animals lacking the IFs. No significant differences were noted between wild-type and single knockout animals.

Conclusions: : The vascular phenotype observed in GV dKO suggests that the inability to express GFAP and vimentin may affect, at least transiently, the maturation and/or activity of cells involved in the process of regression of the hyaloid vascular system, including astrocytes and the lens. The data also show that visual information processing is altered in retinas lacking these IFs, which may occur independently of the vascular alterations.

Keywords: glia • electroretinography: non-clinical • growth factors/growth factor receptors