Regulation of reentrainment function is dependent on a certain minimal number of intact functional ipRGCs in rd mice

Purpose. to investigate the effect of partial ablation of melanopsin-containing retinal ganglion cells (mcrgcs) on nonimage-forming (nif) visual functions in rd mice lacking rods. methods. the rd mice were intravitreally injected with different doses (100 ng/μl,200 ng/μl,and 400 ng/μl) of immunotoxin melanopsin-sap. and then,the density of iprgcs was examined. after establishing the animal models with different degrees of iprgc damage,a wheel-running system was used to evaluate their reentrainment response. results. intravitreal injection of melanopsin-sap led to partial ablation of iprgcs in a dose-dependent manner. the survival rates of iprgcs in the 100 ng/μl,200 ng/μl,and 400 ng/μl groups were 74.14% ± 4.15%,39.25% ± 2.29%,and 38.38% ± 3.74%,respectively. the wheel-running experiments showed that more severe iprgc loss was associated with a longer time needed for reentrainment. when the light/dark cycle was delayed by 8 h,the rd mice in the pbs control group took 4.67 ± 0.79 days to complete the synchronization with the shifted cycle,while those in the 100 ng/μl and 200 ng/μl groups required 7.90 ± 0.55 days and 11.00 ± 0.79 days to complete the synchronization with the new light/dark cycle,respectively. conclusion. our study indicates that the regulation of some nif visual functions is dependent on a certain minimal number of intact functional iprgcs. © 2017 jingxue zhang et al.