Figure 4. Effect of norbixin preventive supplementation from 1.5 to 7.5 months in Abca4-/- Rdh8-/- mice. (A) schematic representation of the 6-month preventive supplementation protocol design. (B) Scotopic A wave, (C) Scotopic B wave, (D) Photopic B wave, recorded after 6 months of oral supplementation with norbixin in Abca4-/- Rdh8-/- mice compared to mice fed with normal chow (vehicle) and to 1.5-month-old mice. (E) Quantification of photoreceptor nuclear layers along the superior and inferior poles of the retina each measured every 200 μm apart from the optic nerve. (F) A2E quantification in eyes from 1.5-month-old Abca4-/- Rdh8-/- mice, 7.5-month-old mice fed with normal chow or with norbixin-containing pellets. Bars represent mean ± s.e.m. with n= 8 mice per group (i.e. n=16 eyes per group for ERG). **p<0.01 compared to vehicle (One-way ANOVA, Dunnett's post-test).