Characterization of the whole Advillin expressing retinal ganglion cell population in the rodent retina

Abstract

Aims/Purpose: We have quantified and examined the topography of the total population of retinal ganglion cells (RGC) expressing Advillin (Advillin+RGCs), an actin‐binding protein expressed in somatic sensory neurons, in the retinas, as well as their projections to the brain, in control adult Advillin‐Cretg/+ mice (Zurborg et al. Mol Pain 2011, 7:66).Methods: Retinas from adult Advillin‐Cretg/+ Ai14fl/fl C57BL/6J mice (Frutos‐Rincón et al., Int J Mol Sci 2022, 23:2997) expressing tdTomato were prepared as whole‐mounts, labelled with antibodies recognizing Brn3a and melanopsin. The entire Advillin+RGC population was quantified and its retinal distribution analysed by nearest neighbour maps. The brains were serial coronal crysectioned and the axonal Advillin+RGC projections in the brain were anatomically analysed.Results: Advillin protein was mainly located in the somas and axons of a subset of RGCs. Total number of Advillin+RGCs was 1947 ± 157 (mean ± SD; n = 7), which constitutes 5% of the total RGC population. Approximately 17.5% (340 ± 76) and 0% (3 ± 1) of the Advillin+RGC population co‐expressed Brn3a or melanopsin proteins, respectively. The Advillin+RGC population was distributed across the entire retina, with a higher concentration in the temporal region. The axons of this RGC subpopulation project to the main retinal recipient regions in the brain, such as the lateral geniculate nucleus (LGN) and superior colliculus (SC). However, none of these axons project to the suprachiasmatic nucleus. These data indicates that Advillin+RGCs is not a subpopulation of ipRGCs.Conclusions: The Advillin protein, which is characteristic of sensory neurons, is also expressed in a specific RGC subpopulation of the adult mouse retina. A small percentage of Advillin+RGCs expressed the Brn3a transcription factor, while none expressed melanopsin. The axons of Advillin+RGCs project to the typical retino‐recipient areas in the brain, excluding the suprachiasmatic nucleus.