Protective effect of ciliary neurotrophic factor on retinal ganglion cell in acute ocular hypertension rat

Abstract

Background Glaucoma associates with apoptosis of retinal ganglion cells ( RGCs).Research showed that ciliary neurotrophic factor (CNTF) can repair optic nerve trauma,but it has not reported whether CNTF has a protective effect on glaucomatous optic neuropathy. Objective This experimental study was to explore the protective effect of CNTF on RGCs in rat eyes with acute ocular hypertension. Methods Ocular acute hypertension models were induced in bilateral eyes of 24 clean Wistar rats by forced perfusion of a balanced salt solution into the anterior chamber.Two days before molding,0.5 μg recombinant human CNTF (5 μl) was injected intravitreously in the left eyes,and 5 mmol/L sodium phosphate solution (5 μl) was injected in the same way as the control group.Three other Wistar rats were used as the normal control group.The animals were sacrificed by excessive anesthesia and the retinal sections were prepared 1,3,7,14 days after molding.The morphology of the retina was examined and RGCs counting was performed by hematoxylin & eosin staining and observed under a light microscope.The expression of glutamic acid in RGCs was assessed by immunochemistry. Results Regular retinal structure with clearly defined cell layers were observed in normal control rats.Changes in vacuoles in RGCs were seen in the model control group.The number of degenerative RGCs decreased in the CNTF group.Compared with the model control group,number of normal RGCs increased from 1 day to 14 days after molding with a significant difference between the two groups (all P=0.000).Immunochemistry assay showed that the numbers of positive cells for glutamic acid were 5.50±1.04 and 6.00±1.41 for the average of 3 fields at 3 days or 7 days in the CNTF group,and those in the model control group were 9.00±2.91 and 10.83 ± 1.94,respectively,showing significant differences between them ( all P =0.000 ).However,no comparable differences were found in the numbers of positive cells for glutamic acid at 1 day and 14 days between the two groups( P=0.578,0.180). Conclusions CNTF down-regulates the expression of glutamic acid in RGCs and offers neuroprotection for RGCs in an acute glaucoma rat model. Key words: Ciliary neurotrophie factor; Ocular hypertention; Retinal ganglion cell; Glutamic acid