Abstract
Purpose:
Axonal transport is an essential requirement for maintaining cellular functions. Impairment of axonal transport is considered an important pathogenic factor in glaucoma and other optic neuropathies in which retinal ganglion cell (RGC) death is fundamental pathology. Syntaphilin has been recently discovered as a docking protein to mitochondria in axonal transport. However, no reports have demonstrated syntaphilin in visual system. The purpose of this study is to investigate the expression of syntaphilin in rat tissues (retina, optic nerve and brain) and human optic nerve.
Methods:
To investigate the localization of the syntaphilin in visual system, we performed immunohistochemistry in rat tissues (optic nerve, retina, brain) without any treatment and one human donor eye without any ocular disease. To evaluate the alterations of syntaphilin expression induced by axonal injury, rat optic nerve was transected (ONT). Three days (3D) and 7 days (7D) after ONT, rats were sacrificed and the optic nerves and retinas were excised. The optic nerves and retinas 3 or 7 days after ONT were used for immunohistochemistory, and real time RT-PCR. Fluorescence intensity of rat optic nerve in cryosections and retrogradely labelled RGC with fluorogold in whole mounted retina was assessed.
Results:
The expression of syntaphilin had similar pattern in rat retina and brain; syntaphilin was expressed in astrocytes, RGC cell body and axon in the optic nerve, and at nerve fiber and cell body of astrocyte and neural cell in brain. On the contrast, syntaphilin was abundant at astrocyte in rat optic nerve, which was confirmed by human optic nerve. ONT caused the reduction of optic nerve fibers and RGC density 7 days after ONT. Syntaphilin gene and protein expression in optic nerve was down regulated at 3 and 7 days after ONT.
Conclusions:
Syntaphilin in the optic nerve was expressed in astrocytes and syntaphilin was donwn regulated by axonal injury. Our study suggests that syntaphilin might relate to axonal degeneration.
Keywords: 429 astrocyte •
613 neuro-ophthalmology: optic nerve