Purchase this article with an account.
S. Baver, T.H. Hill, C.L. Bengston, K.V. Fite; Melanopsin–Immunoreactive Retinal Ganglion Cells in the Aging Mongolian Gerbil . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5522.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Melanopsin–immunoreactive retinal ganglion cells (Mel–ir RGCs) have been described in a variety of mammalian species. We are currently investigating Mel–ir RGCs in the diurnal/crepuscular Mongolian gerbil retina, which contains a higher cone: rod ratio and a lower number of Mel–ir RGCs compared to other rodent species. Doyle et al. (2005; IVOS 46:3988) have reported that the total numbers of Mel–ir RGCs increased in transgenic mice lacking rod photoreceptors. The goal of the present study is to investigate whether, due to aging, there is an effect of decreasing rod and cone photoreceptors on the number and/or distribution of Mel–ir RGCs in the gerbil retina.
Three–month and 1–year old male gerbils (Meriones unguiculatus) were transcardially perfused and one retina was removed for melanopsin immunocytochemistry. Mel–ir RGCs were identified using an antiserum directed against a carboxyl–terminal epitope of the mouse melanopsin protein (generously provided by Dr. K.W. Yau) and counted utilizing a camera lucida system. The opposite eye from each gerbil was embedded in epon and 1µm sections obtained from both superior and inferior hemispheres and were stained with 1% toludine blue. Quantitative analysis of photoreceptor integrity included thickness measurements of the outer nuclear layer (ONL) and photoreceptor nuclei row counts.
A significant increase of 25% was observed in the total number of Mel–ir RGCs in the 1–year compared to the three–month old gerbil (p<0.05). One–year old gerbils also showed a decrease in total thickness of the ONL and fewer rows of photoreceptor nuclei.
These results suggest a possible interaction between the classical photoreceptors and Mel–ir RGC expression. Specifically, these results demonstrate that in the Mongolian gerbil a decline in photoreceptor number is associated with an increase of Mel–ir RGCs.
This PDF is available to Subscribers Only