Purchase this article with an account.
Lian Zhao, Xu Wang, Christopher Parkhurst, Wen-biao Gan, Robert N Fariss, Wai T Wong; Genetic model system for microglia depletion in the adult mouse retina. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2265.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Microglia have been implicated as a contributing factor to retinal disease in humans and animal models. However, endogenous functions of microglia in the healthy adult retina have not yet been well-defined. We describe the use of a genetic model system for depleting microglia in the retina that can be used to study the constitutive contributions of retinal microglia to retinal function.
Transgenic mice on a C57Bl6 background in which the Cx3cr1 gene was replaced by a sequence encoding a mutant Cre protein with a tamoxifen (TAM)-dependent estrogen ligand-binding domain (Cx3cr1CreER) were crossed with mice carrying lox-P-flanked (‘floxed’) diphtheria toxin (DTA) to create Cx3cr1CreER/+DTA+/-(TG) mice. TG mice were gavaged with TAM (500mg/kg) at different time intervals and the density and distribution of retinal microglia analyzed.
Histological comparisons of retinas from young adult (6-12 weeks old) wild type C57Bl6 mice (WT) and control TG mice (not treated with TAM) demonstrated similarities with respect to: 1) retinal anatomy (lamination and thickness of retinal layers), and 2) retinal microglia (distribution, density and morphology). Following gavage with TAM (2 cycles, 2 days apart), near-complete depletion of microglia in all retinal locations and layers was achieved 2 days post-gavage (DPG) as evidenced by Iba1 and CD11b immunohistochemical analyses. Beginning at around 9 DPG, isolated Iba1+ cells with amoeboid to ramified morphologies appeared in the IPL in the peripapillary retinal, spreading into the equatorial retina by 16 DPG. Colonization of the retina from central to the peripheral retina was relatively complete by 30 DPG. Near-complete microglia depletion in the retina was sustained for up to 30 days by repeated TAM gavage, maintaining total retinal microglia densities at ≈0.5% of that in control TG retina.
In the absence of TAM exposure, TG mice demonstrated normal retinal anatomy and retinal microglial distribution, but become highly depleted of microglia following a brief period of TAM exposure. Sustained and near-complete depletion up to 30 days can be induced by maintaining TAM exposure. This genetic system demonstrates utility in studies aimed at studying the contributions of microglia to retinal structure, physiology, and disease.
This PDF is available to Subscribers Only