| Object: To establish an experimental model with incomplete optic nerve injury in rats and evaluate the protective effect of recombinant human ciliary neurotrophic factor (rhCNTF) on the retinal ganglion cells (RGCs) following a moderate incomplete optic nerve injury in rats. Methods: The optic nerve was crushed by a well defined forceps for 5s,10s, 20s and 40s to set up an animal model with incomplete optic nerve injury in rats. Pathological changes were examined by light and electron microscope 7days later. 3,7,14 and 28 days after the injury the visual function changes was examined by the measurement of F-VEP. A moderate optic nerve injury in some rats was immediately followed by intravitreal injections of 2μg rhCNTF, and three additional injections of the same molecule were performed 7,14,28 days after the injury. The eyes in some other rats were injected with distilled water and used as control group. Rats were sacrificed at the 7th ,14th,28th,56th day after optic nerve injury. The RGCs were labeled retrogradely with Granular Blue (GB), and the average density of the RGCs was counted under the fluorescent microscope. The expression of GAP-43mRNA, GAP-43 and GFAP in retina was determined by RT-PCR or immunohistochemical techniques.Results:1.The models were set up and divided into three groups (mild, moderate, severe), ratios of total axons to the optic nerve section area were 74.11%, 54.71%, 30.80%~ 15.14% respectively. The ability for F-VEP to recover reduces with the increasing severity of the optic nerve injury. 2. The survival rate of RGCs on the 7th, 14th, 28th, and 56th day after optic nerve injury in rhCNTF-treated group was 70.18%, 53.09%, 37.30% and 23.97% respectively. And the survival rate in control group was 42.25%, 31.61%, 14.92% and 8.51% respectively. rhCNTF significantly enhanced retinal ganglion cell survival when compared with vehicle .3.The expression of GAP-43mRNA and GAP-43 in retina following moderate optic nerve injury in rhCNTF-treated group was higher than that in the control group.4.The expression of GFAP in retina was higher in rhCNTF-treated group than that in control group.Conclusion:1.The rat models with wild (5s), moderate (10s) and severe (20s or 40s) incomplete optic nerve injury were made with a well defined forceps. The results show that this model provides a reliable standard to describe the severity of optic nerve injury in rats .2.The experiment model with moderate optic nerve injury is suitable to be used in the research of regeneration and nerve protection following optic nerve injury.3.The intravitreal application of rhCNTF can enhance the RGCs long-term survival and may play an important role in the regeneration of axons following a moderate incomplete optic nerve injury in adult rats.4.The intravitreal application of rhCNTF can promote the expression of GFAP in retina following a moderate optic nerve injury and may protect the RGCs indirectly through Muller's cell in retina... |
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