Expression of Nogo-A, NgR mRNA and protein in the retina of rats with chronic elevated intraocular pressure

Abstract

To investigate the expression of Nogo-A and its receptor NgR mRNA and protein in the retina of rats with chronic elevated intraocular pressure (IOP). Experimental study. Rat chronic ocular hypertension (OHT) was induced by obstructing episcleral veins and temporal limber veins. The retinal tissues were collected at day 3, 7, 14 and 28 after the IOP elevated in rats. Each group includes 16 rats and one group served as normal control. Expression of Nogo-A and NgR mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR), while the protein levels of Nogo-A and NgR were expressed by the western blot in rat retinal tissues in different groups. Expression of Nogo-A, NgR mRNA and protein were analysed by one way analysis of variance (ANOV) and multiple comparison ANOV. IOP in rat OHT group was significantly increased after day 3 lasting for 28 day. Compared with control group, the level of Nogo-A mRNA and protein in rat chronic OHT groups were significantly (mRNA: F = 7.464, protein: F = 5.677; P < 0.01) increased at day 7, 14, and 28 (mRNA: 0.661 ± 0.065 vs 0.831 ± 0.055, 0.813 ± 0.063, 0.844 ± 0.077, protein: 1.284 ± 0.043 vs 1.359 ± 0.033, 1.381 ± 0.063, 1.361 ± 0.044), respectively. There is a tendency of increase of Nogo-A mRNA expression at day 3 but did not reach statistical significance. However, the level of NgR in the retina in rats with the chronic OHT was not significantly (mRNA:F = 0.598, protein:F = 0.460; P > 0.01) changed compared with normal group. The increased expression of Nogo-A in retina of rat OHT indicates that Nogo-A may play a primary role in obstructing regeneration of optic nerve, which is mediated by other receptors and elements rather than NgR.