Immunotoxin‐induced ablation of melanopsin retinal ganglion cells in a non‐murine mammalian model

Abstract

In mammals, non-image-forming visual functions, including circadian photoentrainment and the pupillary light reflex, are thought to be mediated by the combination of rods, cones, and the melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs). Although several genetic models have been developed to clarify the individual roles of the rod, cone, and ipRGC systems in mediating non-image visual function, assessing the in vivo role(s) of the ipRGCs has been complicated by the possibility of ontogenetic issues in these genetically modified animal models. In the present study, we describe the development and validation of an immunotoxin that specifically targets the ipRGC population in the mature mammalian retina. This ipRGC immunotoxin, consisting of saporin conjugated to a melanopsin polyclonal antibody, was evaluated with respect to its effectiveness and specificity in depleting the ipRGC population in the fully developed rat retina. The results showed that the ipRGC toxin rapidly and permanently depleted approximately 70% of the ipRGC population, without inducing appreciable changes in the cell number or morphology of any of the non-melanopsin-containing retinal cell populations investigated. These findings suggest that the newly developed ipRGC immunotoxin provides a potent method for achieving relatively rapid, permanent, and selective depletion of the ipRGC population in a non-murine model system. The development of this ipRGC-ablation method is the next step in elucidating the role of ipRGCs in mediating non-visual and circadian light-resetting responses in a wide range of non-murine mammalian models.

Neurochemical and Structural Organization of the Principal Nucleus of the Inferior Olive in the Human

“…The neurofilament H antiserum recognizes only nonphosphorylated epitopes (nonphosphorylated neurofilament protein, abbreviated NPNFP, also abbreviated SMI-32; Covance, Emeryville, CA and Sternberger Monoclonals, Baltimore, MD) on the medium (170 kDa) and heavy (200 kDa) molecular weight subunits of neurofilament H in immunoblots of mammalian brainstem and spinal cord tissue (described in Sternberger and Sternberger, 1983;Lee et al, 1988;Ingham et al, 2009 and in manufacturers' data sheets).…”

Why Directionality Is an Important Light Factor for Human Health to Consider in Lighting Design?

“…Fifteen studies have investigated the spatial distribution of ipRGCs in animal retinas [2,20,21,[24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Most of the experiments were carried out using different rat species e.g.…”

“…Most of the experiments were carried out using different rat species e.g. wildtype, albino, and pigmented [21,25,[27][28][29][30][31][32][33][34][35] while only a few ones used primate [24,26] and cat [37]. To identify the location and population of the ipRGCs, a cell-tracer was injected into different central targets.…”

“…Despite of methodological differences in the reviewed animal studies, ipRGCs were found to be denser in the superior (dorsal) and temporal retinal areas [21,24,25,[27][28][29][30][31][32]34,35]. Among all these studies [2,20,21,[24][25][26][27][28][29][30][31][32][33][34][35][36] only three have considered different subtypes of ipRGCs in their analysis [29,30,33].…”

“…Among all these studies [2,20,21,[24][25][26][27][28][29][30][31][32][33][34][35][36] only three have considered different subtypes of ipRGCs in their analysis [29,30,33]. Whereas Hughes et al [30] investigated the whole-mount retina, Esquiva et al [29] and Jeong et al [33] studied only a part of retina.…”