Accelerated retinal aging in PACAP knock-out mice

•Histology did not show marked differences in retina layers between WT and KO mice.•Calbindin-positive horizontal cell dendrites sprout into the ONL in aging retinas.•PKC alpha protein level was found consistently less in KO animals compared to wild type.•In aging KO animals GFAP level is elevated in Müller cells while PAC1-R staining decreases compared to the aging WT retina.•PACAP may act as an endogenous juvenating factor in the retina.