GLIAL REACTIVITY IN THE RETINA OF ADULT-RATS

The present study aimed to characterize the reaction of mammalian (rat ) retinal macroglia (Muller cells and astrocytes) to disturbances of t heir environment in the form of intraorbital section of the optic nerv e, intraocular insertion of a thin glass capillary (without damage to the retina) or a combination of both. Glial reactivity was assessed th rough the use of a battery of antibodies which recognise four differen t proteins-glial fibrillary protein (GFAP) and three other proteins de signated respectively MA1, 4D6 and 4H11. Retinal astrocytes did not ex hibit any changes in normally expressed GFAP or MA1. By contrast, the expression of GFAP and MA1 in Muller cells increased 14 days following section of the optic nerve and/or intravitreal insertions of a glass capillary. Three days postoperatively, the expression of GFAP, but not MA1, had already increased significantly in Muller cells. 4D6 and 4H1 1 proteins were not expressed in astrocytes. In Muller cells, the leve ls of these proteins increased significantly following combined optic nerve section and intraocular insertion of a glass capillary. Thus, a mechanical disturbance of the intraocular environment constitutes a mo re effective stimulus in increasing the expression of some Mullerian p roteins than damage to the axons of retinal ganglion cells. Such chang es have important implications for various ocular treatments that invo lve intraocular administration of drugs, as well as for the survival/r egeneration potential of retinal ganglion cells undergoing Wallerian d egeneration. (C) 1995 Wiley-Liss, Inc.