Diphtheria Toxin-Induced Retinal Injury

Procedures regarding the diphtheria toxin injection timing and concentration followed the method previously described (Hillier et al., 2017 (link); Kim et al., 2020 (link)). Mice were anesthetized for intraocular injection using a mixture of ketamine (80 μg/kg) and xylazine (5 μg/kg). Glass micropipettes for injection were prepared using a P1000 micropipette puller (Sutter Instruments). Injection was performed using a Nanoject III precision pipette (Drummond Scientific). DT (D0564, Millipore Sigma) was diluted to a working concentration of 0.8 ng/μl, and 2 μl was injected into the intravitreal space of each eye twice, 48 h apart. For some mice, 2 μl DT solution at a concentration of 5 ng/μl was injected to the intravitreal space only once. Subsequent behavioral and cellular experiments were conducted 6–10 d after the initial DT injection. Control mice were injected with 0.9% normal saline in both eyes on the same schedule as toxin-injected mice.