Axonal transport along retinal ganglion cells is grossly intact during reduced function post-injury

It has been established that beyond middle age, mice are slower to recover inner retinal function following an acute intraocular pressure (IOP) injury. While 3 month old animals exhibit near-complete recovery 1 week following injury, 12 and 18 month old animals demonstrate prolonged inner retinal dysfunction. In this study we aim to determine whether age-related differences in functional recovery of the inner retina are due to differences in retinal ganglion cell (RGC) axonal transport. C57BL/6J mice at 3 (n = 8) and 18 months (n = 8) of age were used. At day 0, right eyes were cannulated and the IOP was maintained at 50 mmHg for 30 min. At day 5, mice received bilateral intravitreal injections of choleratoxin subunit B (CTB) conjugated to Alexafluor 488. At day 7, mice were euthanized and tissue was collected. Axonal transport of CTB was quantified in retinas and superior colliculi (SC) using fluorescent microscopy. In response to IOP elevation, the overall degree of axonal transport was comparable between young and old mice. Furthermore, no differences in axonal transport were detected between control eyes and injured in mice at any age. In conclusion, impaired recovery of inner retinal function 1 week following acute IOP injury in old mice is not associated with changes in active axonal transport in RGCs at this time.