Effect of eye NGF application on NGF‐receptor expression in visual cortex and geniculate nucleous of rat with glaucoma

• Published in: Acta ophthalmologica (Oxford, England) Vol. 86; no. s243
• Main Authors: ALOE, L, PARISI, V, MANNI, L, SPOSATO, V
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2008
• ISSN: 1755-375X; 1755-3768
• DOI: 10.1111/j.1755-3768.2008.503.x

Purpose Glaucoma (GL) is an ocular disorder characterized by retinal ganglion cells loss and deficits of brain visual pathways. We have shown that eye topical application of nerve growth factor (NGF), a signaling molecule involved in neuroprotection, can reach brain NGF‐responsive neurons. In this study, we investigated whether (i) experimentally‐induced GL alters the presence of NGF and its receptors in the geniculate nucleus (GN) and visual cortex (VC); (ii) and whether application of NGF eye drops influences these biomarkers. Methods GL was induced in rats with hypertonic saline injected into the right episcleral vein. After seven weeks, glaucomatous and control rats, untreated and treated with eye NGF application, were sacrificed and the presence of NGF, the expression of NGF‐receptors in brain visual areas determined using structural, biochemical and molecular analyses. Results GL reduces the concentration of NGF in the CSF, GN and VC, enhances the presence of the NGF/TrkA receptor in the GN, decreases this receptor in the VC. The NGF/p75 receptor is unaffected in the GN and down‐regulated in the VC. In glaucomatous rats, topical eye NGF application for 35 consecutive days, enhances the concentration of NGF in the CSF, normalizes its presence in the VC and GN, and induces up‐regulation of NGF/TrkA receptor Conclusion Our findings suggest that, GL induced by elevated intraocular pressure significantly impairs the presence of NGF and NGF receptors in the VC and GN. It remains to be established whether NGF application could provide a functional benefit for the protection of GN and VC damaged neurons. Supported by CNR and by “Fondazione Bietti” Roma”, Grant N° RF‐FGB‐2005‐150198