Nerve Growth Factor and Its Receptors in a Rat Model of Experimental Glaucoma

Abstract

Purpose:: to evaluate the changes in the levels of NGF and its receptors p75 and TrkA in an animal model of glaucoma. NGF is a well-known neurotrophin, while it is established that p75 is involved in the apoptosis cascade.

Methods:: glaucoma was induced through the injection of hypertonic saline in an episcleral vein of 18 rats. Six animals underwent sham surgery and were used as control. Animals were sacrificed 1, 3 and 5 weeks after the induction of glaucoma. Immunohistochemistry, ELISA analysis and real time-PCR technique were applied to the retinas to evaluate the levels of NGF, TrkA and p75.

Results:: NGF, p75 and TrkA were produced and expressed in the rat retina. A significant increase of both NGF mRNA and protein was observed at 1, 3 and 5 weeks. NGF receptors were over-expressed during the hypertensive injury and the p75/TrkA ratio was increased during the first 3 weeks, but decreased at 5 weeks.

Conclusions:: the increased level of NGF in glaucomatous retinas may be a response to the pressure damage and an attempt to support the retina ganglion cells survival. In line with this hypothesis, the balance between p75 and TrkA is altered in our animal model. These data warrant further investigation on the role of NGF in human glaucoma.

Keywords: growth factors/growth factor receptors • neuropeptides • neuroprotection