| Congenital stationary night blindness (CSNB) is a disease that may be inherited in any fashion. The mainly defect of CSNB is the rod vision system. According to the ERG, we can get an important objective diagnosis. The CSNB rat found in our laboratory provides an important animal model to study CSNB. According to the different stages of the ERG development, we can get the characteristics of the CSNB development. These features can provide a further diagnosis of the CSNB, offer some valuable suggestions for the treatment and may be useful for understanding the origin of ERG wave.Age factor play an important role on the result of the ERG of the CSNB rat. Since the different characteristic of ERG in the different development stages, main objects of this research were as following: 1.the variation of ERG between the normal Sprague-Dawley rat (SD rat) and the CSNB rat of our laboratory before their eye lids were open. 2. The variation of ERG between the normal SD rat and CSNB rat of our laboratory after their eye lids were open. 3. To discuss the different morphology feature between the normal SD rat and the CSNB rat with HE dyeing. 4. To discuss the Ultrastructural characteristics of the normal SD rat and the CSNB rat with the electron microscope.Methods and material:Sprague-Dawley albino rats (male or female) and the CSNB like rats (male orfemale) were used in present study and grouped according to the different experimental settings. The RETI-port system (Roland Consult, Germany) and the GT-2000NV system (the ChongQing GuoTe medical equipments company) to detect the ERG of the two type of rats. We detect the ERG following the standard of ISCEV and the standard plan for animals of our laboratory. To observe the retinal morphology of the CSNB rat from P7 to P60 with the paraffin embed and HE stain; To observe the ultrastruction of the CSNB retina from P7 to P60 with the transmission electron microscope;Result1. The characteristics of the ERG of normal SD rat and CSNB rat before their eye lids were open.The characteristics of the ERG of normal SD rat and CSNB rat before their eyelids open were almost the same. In normal SD rat, we can not record the Rod-ERG wave from P9 to P13. It was the same in CSNB rat. Of the Max-ERG in normal SD rat, a wave can first be elicited in P10. There is only a negative tendency in P9. The a-wave was smoothed in P11, P12 and P13. The b wave of Max-ERG was not educed until P13. The O1 wave of OPs was first elicited in P10, and it was the only wave of OPs before their eyelids were open. We can't record Cone-ERG before P13. However, the wave of Cone-ERG at P13 was almost the same as the mature SD rat. Flick-ERG at 20Hz was recorded. The wave of Flick-ERG was dominant form P9. An interesting thing is that the variation of the amplitude of Flick-ERG. The amplitude was almost the same form P9 to P12, and the wave was easy to elicit. However, it was not easy to elicit the wave of the Flick-ERG at P13, and the amplitude was declined.We can't get the Rod-ERG all the time.The a-wave of Max-ERG of CSNB rat was first recorded on P10. We can hardly find the tendency to downward on P9. The b-wave can not be induced from P9 to P13. Just like the SD rat, the O1-wave was the only wave of OPs. Cone-ERG can not be elicited from the beginning to the end. Flick-ERG, with the stimulus frequency at 20Hz, was easy to induce from P9. Thecharacteristic of the Flick-ERG was the similar to the SD rat. The wave was a little mild compared with that of SD rat. The amplitude of Flick-ERG at different time varied little, however it was declined on P13 just like the SD rat. 2. The characteristic of the ERG of normal SD rat and CSNB rat after their eye lids were open.In the normal SD rat group, the Max-ERG a-waves, OPs O1 waves shared the almost same latency at different stages. The latency and amplitudes of Rod-ERG b-waves, Max-ERG b-waves, Cone-ERG b-waves, OPs O2 waves at P14 were different from those at other stages, the same happened with the amplitudes of OPs O1 waves, Max-ERG a-waves and the Flick-ERG. The amplitudes of Rod-ERG, Max-ERG and Cone-ERG in P14 were low compared with those in P56, the latency was prolonged, and the waves were relatively mild at the same time. Still, the latency of O2 in P14 was much longer than other times. There are 5 to 6 waves of OPs in P21.The Flick-ERG was hardly to detected in P14 with the stimulus frequency at 30Hz.However, in the CSNB rat group, the amplitudes and latency of Max-ERG a-waves, OPs O1 waves, Cone-ERG b-waves are of no obvious differences. There is only one negative a-wave of Max-ERG in CSNB rat. The O1 wave was the only wave of OPs. The characteristic of Cone-ERG and Flick-ERG were similar to those of SD rat.When we compared the normal SD rat group and the CSNB rat group, we found that the Max-ERG a-waves, Cone-ERG b-waves at P14 shared almost the same amplitudes and Latency. And the latency of O1 waves at different stages were same, however the amplitudes of O1 waves were of much differences at all stages except for P14.3. The morphology characteristics of CSNB and SD rats.With the HE stain, it can be got that the morphology development has no difference between CSNB and SD rats. The outer plexiform layer (OPL) appered on P7. The outer nuclear layer (ONL) is still thick on P10. There are 1-2 layers of ganglion cells and the OPL is thin onP10. The morphology development of retina is almost mature on P28 and P60. At these times, the inner plexiform layer (IPL) and OPL is thickening. 4. The Ultrastructural characteristics of the SD and CSNB ratsThere are more membranous discs in the CSNB rat than that of SD on P7. The oriention of SD rat is relative regular but it is in chaos in CSNB rat. The gap between membranous discs is a few bigger than SD rat. There are 3-4 layers of ganglion cells in SD rats, however there are only 1-2 layers in CSNB rats.In P12, the membranous disc of SD rat is parallel to RPE on the whole, while the CSNB is still in the chaos. The vacuolization in the mitochondria (Mi) can be seen in the gangllion cells of CSNB rats.The retina of SD rat is almost matured in P28 in P60. However, the membranous disc of CSNB is still anomalism. The vacuolization in Mi and expansion in endocytoplasmic reticulum is existed, too. Besides, the OPL is thinner than SD rats.Conclusion1. The characteristics of normal SD rat and CSNB rat before their eye lids were open were almost the same. The wave of Rod-ERG can not be elicited in both of them. It was difficult to record the wave of Cone-ERG in SD and CSNB rat. However, the Cone-ERG of SD rat in P13 was similar to that of mature one. we can take nothing in CSNB rat at the same time. In P9, the Max-ERG can not be elicited in both the SD and CSNB rats. The a-wave of Max-ERG was first detected in P10 in SD rat. The amplitude of a-wave was increased gradually. There is a conspicuous increase in P13. The latency of a-wave was relatively stable. The latency of O1 wave was stable too, and the amplitude was raise up step by step. The amplitude of Flick-ERG in P9 and P13 were low compared with other time like P10, P11 and P12.In CSNB rat, the amplitude of a-wave of Max-ERG increased apparently from...
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