The Effect of Heat Shock Protein 70.1 gene (hsp70.1) on Retinal Ganglion Cell Damage after Partial Lesion of the Optic Nerve in Mice

ABSTRACT

PURPOSE: Heat shock protein (HSP) 70 has been known to have neuroprotective effect on the retinal ganglion cells (RGCs) in vitro and in a rat glaucoma model. This study was to evaluate the inducible HSP70 expresseion in the retinal ganglion cell (RGC) after partial crush injury in mice and to determine the effect of hsp70.1 on the RGCs in the normal condition and after partial crush injury of the optic nerve. METHODS: The optic nerve was crushed by clipping optic nerve with aneurysm clip (110G) for 30 seconds. H and E staining and immunohistochemical staining for inducible HSP70 was performed in the hsp70.1 knockout mice and wild type mice. The RGC counts before crush injury were compared and the losses of RGCs after 3 weeks were compared between the two groups. Loss of RGCs was monitored as a percentage of cells decreased relative to the contralateral sham-operated eye. RESULTS: Immunohistochemical staining showed HSP70 induction in the RGC layer after optic nerve crush injury in both hsp70.1 knockout mice and wild type mice. RGC count before crush injury showed no significant difference (n=8, Mann-Whitney test), and the loss of RGCs was 31.0%+/-0.1% (mean+/-SD) in the hsp70.1 knock-out mice and 32.6%+/-0.1% in the wild type mice without any significant difference between the two groups (n=8, Mann-Whitney test). CONCLUSIONS: HSP70 was induced in the mice RGC layer by optic nerve crush injury and the hsp70.1 gene didn't affect the RGC counts in normal condition and RGC survival after optic nerve crush injury in the mouse.