Astrocyte Proliferation and GDNF Up-Regulation in the Lateral Geniculate Nucleus of Experimental Primate Glaucoma

Abstract

Purpose:: To investigate the changes of astrocyte reactivity and glial cell line-derived neurotrophic factor (GDNF) expression in the lateral geniculate nucleus (LGN) following experimental primate glaucoma.

Methods:: Five rhesus monkeys with monocular experimental glaucoma and four control monkeys were studied. Brain sections containing the LGN were examined following immunocytochemical staining with antibody to GFAP, S-100 and GDNF. Double immunolabelling of GDNF with GFAP and parvalbumin respectively were also studied in the LGN by confocal microscopy. Optic nerve fiber count was determined by light microscopy.

Results:: In the normal LGN, a few GFAP, S-100 and GDNF expression were observed across layer 1 to 6. GFAP and S-100 positive glial cells were significantly increased in layers connected to the glaucomatous eye compared with those connected to the non-glaucomatous eye. Moreover, GFAP and S-100 expression were increased in layers connected to the non-glaucomatous eyes compared to the corresponding layers in control group, which is more evident in severe glaucoma with 100% optic nerve fiber loss. Expression of GDNF protein was also increased in layers connected to the glaucomatous eye. Double immunostaining showed that the GDNF expression was mainly of glial origin.

Conclusions:: Experimental glaucoma induces astrocytes proliferation and GDNF up-regulation in the lateral geniculate nucleus. The findings may be relevant to understanding the role played by glial cells in the central visual system of glaucoma.

Keywords: thalamus/lateral geniculate nucleus • glia • neuroprotection