Abstract
Purpose :
Mutations in the mouse microphthalmia (mi) gene affect the differentiation and development in most cell types including the retinal pigment epithelium (RPE). Here for the first time, we examined the retinal function in heterozygous the microphthalmia (Mitfmi) mice.
Methods :
Mitfmi/+ mice at 1 and 3 months old compared with C5BL/6J (as control) mice at the same ages were examined in this study. Fundus photography and electroretinograms (ERGs) under both dark- and light-adapted conditions were performed on anesthetized mice. The ERG dark-adapted a-, b- and c-waves were analyzed along with light-adapted a- and b-waves amplitude.
Results :
Light-adapted a-wave amplitude was significant lower in 3-month-old mutants (5.17± 1.24 µV, 7.34 ± 1.33 µV, 7.51 ± 1.19 µV, 8.58 ± 1.03 µV, 12.74 ± 2.21 µV, 15.83 ± 1.45 µV; p < 0.05) compared with controls at all light intensities tested. Furthermore, light-adapted b-wave amplitude was also significantly reduced in 3-month-old mutants (22.13 ± 0.95 µV, 35.09 ± 2.72 µV, 57.71 ± 5.17 µV, 66.16 ± 4.49 µV, 85.87 ± 4.28 µV; p < 0.05) compared with controls at all light intensities tested. Surprisingly, c-wave amplitude was significantly lower in 1-month-old (150.80 ± 11.91 µV; p < 0.05) and 3-month-old Mitfmi/+ (134.70 ± 5.45 µV; p < 0.05) compared with controls at 10 cd*sec/m2 light intensity. Areas of progressive hyper- and hypopigmentation were visualized in the mutants’ fundi.
Conclusions :
RPE pigmentation and function was greatly affected in the mutants at all ages. Lower light-adapted a- and b- wave responses indicate selective cone-dystrophy in the Mitfmi/+ mutant mice.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.