Purchase this article with an account.
Hung-Ya Tu, April Bang, Adam R McQuiston, Chuan-Chin Chiao, Ching-Kang Jason Chen; Increased dendritic branching in direction selective retinal ganglion cells in nob1 mice. Invest. Ophthalmol. Vis. Sci. 2014;55(13):712.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Persistent retinal waves in nob1 mice result in abnormal ganglion cell projections to the brain. However, it remains unclear whether dendritic morphology and synaptic connectivity are also altered in the retina. Therefore, we examined the dendritic development of a genetically identified retinal ganglion cell in the nob1 background.
Transgenic mice expressing GFP under the control of a thyrotropin-releasing hormone receptor promoter (Gong et al., 2003; Rivlin-Etzion et al., 2011) were obtained from Dr. William Guido and crossed into the nob1 background. Intrinsic membrane properties of GFP-positive ganglion cells were recorded by whole-cell current clamp with potassium-based internal solution containing biocytin. The dendritic morphologies of recorded cells were visualized by dye-conjugated streptavidin. Image stacks were acquired in a Zeiss LSM-710 at 0.5 μm z-interval and traced in the Neurolucida program for quantitative morphometric analyses.
The wild type GFP-positive ganglion cells displayed characteristic intrinsic membrane properties and were bistratified with dendrites co-fasiculated with cholinergic amacrine cells as previously reported (Rivlin-Etzion et al. J Neurosci 31:8760-8769, 2011). In the nob1 background, membrane potentials of these cells oscillated with a characteristic peak frequency of 4-6 Hz, first observed around postnatal day (P) 15 (4.1±0.1 Hz, n=7) and persisted into adulthood (5.9±0.2 Hz at P28, n=11; p < 0.001). Cells in heterozygous female (S+) mutants possessed hyper synaptic activity but not rhythmic oscillations as observed in homozygous female and mutant male animals. The numbers of dendritic branching points in adult ganglion cells in the nob1 and S+ backgrounds were significantly higher than those of the control animals. We also examined GFP-positive cells in adult mice lacking Gβ5 and R7 RGS proteins where ERG b-waves were similarly missing. We found that they oscillated similarly to nob1 mice (4.9±0.4 Hz; n=11; p > 0.05) but surprisingly did not display differences in their dendritic morphologies.
The results from the nob1 mice suggest that rhythmic and arrhythmic hyperactivities in the retina facilitate dendritic branching in this bistratified ganglion cell type. The lack of such a phenotype in mice lacking Gβ5 and R7 RGS proteins implies that these proteins may have a cell-autonomous role in dendritic development and/or plasticity.
This PDF is available to Subscribers Only