Figure 5.

There is a delayed synthesis of amino acids from¹⁵N proline in the retina compared with the RPE/Cho.A, a schematic of in vivo tracing of ¹⁵N proline with double injection. Mice were fasted for 18 h and received two injections of ¹⁵N proline (150 mg/kg) or PBS at 0 min and 10 min, respectively. Retina and RPE/Cho were harvested at 0, 5, 15, and 30 min after the second injection for metabolite analysis with GC–MS. B–K, ¹⁵N fraction of proline and metabolites derived from ¹⁵N proline in RPE/Cho and retina at different time points. N = 8. L, a schematic of proline catabolism into amino acids in RPE to be exported into the neural retina. Error bars represent SD. Cho, choroid; RPE, retinal pigment epithelium.