Objective To investigate the effect of N-methyl-N-nitrosourea (MNU) on expressions of interphotoreceptor retinoid-binding protein (IRBP) and recoverin in rat retinal. Methods Thirty female SpragueDawley (SD) rats were randomly divided into five groups, including normal control group, and MNU treatment one day, three days, seven days and 10 days groups, each group had six rats. Rats in MNU-treatment groups received a single intraperitoneal injection of 40 mg /kg MNU, while rats in the normal control group received intraperitoneal injection of saline 5 ml/kg. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence were used to detect the retinal expression of IRBP and recoverin. Results RT-PCR results indicated that retinal IRBP levels decreased after MNU injection compared with normal control (P＜0.01)，while recoverin levels increased (one day: P＞0.05; three days: P＜0.05; seven days: P＜0.5; 10 days：P＜0.05). Immunofluorescence assays demonstrated that normally IRBP protein is mainly in the inner and outer segments of photoreceptors. After MNU treatment, IRBP protein was detected in all retinal layers but much faint. Recoverin was expressed in the inner nuclear layer, inner plexiform layer and ganglion cell layer, and its expression was increased after MNU injection. Conclusion MNU suppresses IRBP expression and promotes recoverin expression in rat retina.
