Anti-OPN4 (C-terminal) polyclonal antibody

Intrinsically photosensitive retinal ganglion cells (ipRGCs) are inner retinal photoreceptors that mediate non-image-forming visual functions, e.g. pupillary constriction, regulation of pineal melatonin release, and circadian photoentrainment Five types of ipRGCs were recently discovered in mouse, but whether they exist in other mammals remained unknown. We report that the rat also has five types of ipRGCs, whose morphologies match those of mouse ipRGCs; this is the first demonstration of all five cell types in a non-mouse species. Through immunostaining and lambda(max) measurements, we showed that melanopsin is likely the photopigment of all rat ipRGCs. The various cell types exhibited diverse spontaneous spike rates, with the M1 type spiking the least and M4 spiking the most, just like we had observed for their mouse counterparts. Also similar to mouse, all ipRGCs in rat generated not only sluggish intrinsic photoresponses but also fast, synaptically driven ones. However, we noticed two significant differences between these species. First, whereas we learned previously that all mouse ipRGCs had equally sustained synaptic light responses, rat M1 cells' synaptic photoresponses were far more transient than those of M2-M5. Since M1 cells provide all input to the circadian clock, this rat-versus-mouse discrepancy could explain the difference in photoentrainment threshold between mouse and other species. Second, rat ipRGCs' melanopsin-based spiking photoresponses could be classified into three varieties, but only two were discerned for mouse ipRGCs. This correlation of spiking photoresponses with cell types will help researchers classify ipRGCs in multielectrode-array (MEA) spike recordings. (C) 2014 Elsevier Ltd. All rights reserved.

Purpose: To test the hypothesis that in young, functionally blind mice, light-dependent intraretinal ion regulation occurs via melanopsin. Methods: Postnatal day (P) 7 wild type (WT, C57B1/6) and melanopsin knockout (KO, opn4-/-, B6129) mice were light or dark adapted. Awake and freely moving animals were injected intraperitoneally (ip) with MnCl(2). Four hours later, the mice in both groups were anesthetized and studied with manganese-enhanced MRI (MEMRI) to measure the extent of intraretinal uptake of manganese and whole retinal thicknesses. Results: In control P7 mice, light exposure increased (p<0.05) retinal manganese uptake over that in dark. This difference was observed throughout most of the retina. In P7 KO mice, intraretinal manganese uptake did not differ from that in age-matched dark-adapted WT mice, and was not light-dependent. No differences in whole retinal thickness were noted between groups. Conclusions: First time evidence is presented which demonstrates intraretinal ion regulation by melanopsin in vivo.