Protective effects of cerebrolysin in a rat model of optic nerve crush.

To investigate the effects of cerebrolysin (Cbl) on optic nerves (ON) and retinal ganglion cells (RGC) in a rat model of ON crush. Rats received intravitreal injection of Cbl (n = 20), intra-ON injection of Cbl (n = 20), intraperitoneal injection (IPI) of Cbl (n = 20), or phosphate buffered saline (PBS; n = 20) every day for 2 weeks after ON crush injury. At 3 weeks post-trauma, RGC density was counted by retrograde labeling with FluoroGold and visual function was assessed by flash visual-evoked potentials. Activities of microglia after insults were quantified by immunohistochemical analysis of the presence of ED1 in the optic nerve. At 3 weeks postcrush, the densities of RGCs in the Cbl-IVI group (1125 ± 166/mm(2)) and in the Cbl-IPI treatment group (1328 ± 119/mm(2)) were significantly higher than those in the PBS group (641 ± 214/mm(2)). The flash visual-evoked potential measurements showed that latency of the P1 wave was significantly shorter in the Cbl-IVI- and Cbl-IPI-treated groups (105 ± 4 ms and 118 ± 26 ms, respectively) than in the PBS-treated group (170 ± 20 ms). However, only Cbl IPI treatment resulted in a significant decrease in the number of ED1-positive cells at the lesion sites of the ON (5 ± 2 cells/vs. 30 ± 4 cells/high-power field in control eyes). Treatment with intra-ON injection of Cbl was harmful to the optic nerve in the crush model. Systemic administration of Cbl had neuroprotective effects on RGC survival and visual function in the optic nerve crush model.

Factors influencing the retrograde labeling of retinal ganglion cells with fluorogold in an animal optic nerve crush model.

PURPOSE: To investigate whether different crush durations or a different fluorogold (FG) injection timing can affect the efficiency of FG retrograde labeling of retinal ganglion cells (RGCs) in the optic nerve (ON) crush model. METHODS: We performed the ON crush in rats with a clip at different durations or a jewel forceps to compare the effects of different crush methods with FG staining. RGC density was compared between the FG injection 1 week before the sacrifice of the animals (group A) and the injection before the crush experiment (group B). Double staining with CD11b and FG in the retinal sections was conducted to investigate the relationship between the overcounting of RGCs and microglia. RESULTS: The FG-stained particles were significantly decreased at the distal part of the crush site compared to the proximal site of the ON with a crush duration of over 30 s or when crushed with the jewel forceps. Two weeks after ON crush, the RGC count was higher both in the central and mid-peripheral retinas in group B. The percentage of CD11b-stained cells among the FG-stained cells in the RGC layer of retinas in group B was higher than that of group A (34% in group B vs. 4% in group A, p = 0.0001). Overcounting of RGC density in group B was due to additional microglia with FG engulfing. CONCLUSIONS: Our results suggest that each laboratory should test its setting conditions to avoid factors influencing the RGC density measurement before conducting ON crush experiments.