Abstract
Purpose:
Our previous report demonstrated that immediate administration of recombinant human granulocyte colony-stimulating factor (G-CSF) had neuroprotective effects in a rat model of anterior ischemic optic neuropathy (rAION). This study is aim to investigate whether delayed treatment of G-CSF is as effective as early treatment after rAION induction.
Methods:
The rAION rats were subcutaneously injected G-CSF starting at day 0, 7, and 14-post rAION induction for 5 consecutive days. Survival rate of retinal ganglion cells (RGCs) was determined by using retrograde labeling of Fluorogold. Apoptosis in RGCs layer and inflammation at optic nerve (ON) were measured by TUNEL assay and immunohistochemical (IHC) staining of ED1 respectively. Visual function was assessed by photoptic flash visual evoked potentials (FVEP).
Results:
G-CSF treatment started at day 0-post rAION induction had significant better survival rate of RGCs than treatments at day 7 and 14-post infarct both in central and mid-peripheral retinas (p<0.05). Treatment with G-CSF at day 0-post rAION induction resulted in significantly lower number of apoptotic cells in RGCs layer of retinas and significantly lower level of inflammation at ON than treatment at day 7 and 14-post rAION induction (p<0.05). Rats received G-CSF treatment at day 0-psot rAION induction preserved better latency and amplitude of the p1 wave in FVEP than rats treatment with G-CSF at day 7 and 14-post rAION induction (p<0.05).
Conclusions:
Early treatment with G-CSF has significantly better neuroprotective effects on RGCs and optic nerve than the delayed treatment starting at 1 or 2 weeks post-infarct.