Representative scotopic and photopic ERGs recorded from WT mice and
Ctrp9-KO mice at 8 and 24 weeks of age are shown in
Figure 1. The stimulus intensity-response curves of the WT mice and KO mice at 8 and 24 weeks of age are shown in
Figure 2. The scotopic ERGs elicited by each stimulus level did not differ between the two types of mice. There were no significant differences in the scotopic a- and b-wave amplitudes between WT mice and KO mice at all stimulus levels at 8 and 24 weeks (
Figs. 2A,
2B,
2D,
2E). On the other hand, the photopic ERGs were smaller at stimulus levels of 0.4 and 1.0 log cd s/m
2 in the KO mice than in the WT mice at 8 and 24 weeks (see
Fig. 1B). The b-wave amplitudes in the KO mice were significantly smaller for 0.4 and 1.0 log cd s/m
2 at 24 weeks and at 1.0 log cd s/m
2 at 8 weeks (
Figs. 2C,
2F,
P < 0.01, repeated measures ANOVA). There were no significant differences in the amplitudes of the scotopic a- and b-waves and the photopic b-waves between 8 and 24 week old in KO mice. ERG findings in WT and KO mice at stimulus level of 1.0 log cd s/m
2 are shown in
Supplementary Table S2. The implicit time of the photopic b-wave was 62.7 ± 1.6 ms (mean ± SEM) in the WT mice and 65.2 ± 1.0 ms in the KO mice, and there were no significant differences between WT mice and KO mice for 1.0 log cd s/m
2 at 8 weeks of age. On the other hand, the implicit time of the photopic b-wave were significantly delayed in the KO mice for stimulus level of 1.0 log cd s/m
2 at 24 weeks (WT = 50.4 ± 1.8 ms; KO = 60.0 ± 3.0 ms;
P < 0.01: Mann–Whitney
U test). There were no significant differences in the amplitudes of the oscillatory potentials between WT mice and KO mice at stimulus level of 1.0 log cd s/m
2 at 8 and 24 weeks of age. There were no significant differences in the photopic a-wave amplitudes between WT mice and KO mice at stimulus level of 1.0 log cd s/m
2 at 8 weeks. On the other hand, the photopic a-wave amplitudes were significantly smaller in the KO mice than that of the WT mice for 1.0 log cd s/m
2 at 24 weeks of age (WT = 22.3 ± 1.5 µV; KO = 15.5 ± 1.3 µV;
P < 0.01: Mann–Whitney
U test).