Purchase this article with an account.
P.D. Parikh, S.J. Heflin, P.B. Cook; Diversity of GABAergic and Glycinergic Amacrine Cell Dendritic Fields in Tiger Salamander Retina . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5350.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose:Amacrine cells (ACs) of the salamander retina provide sustained GABAergic and transient glycinergic inhibition to ganglion cells, and it has been shown that the lateral extent of the GABAergic signal is narrower (<250 µm) than the glycinergic signal (>250 µm). Recently, others concluded from general immunocytochemical staining that GABAergic ACs have wide dendritic fields, while glycinergic ACs are narrow. We stained fixed retinal slices with either GABAergic or glycinergic antibodies and used targeted injection of DiO to determine AC dendritic fields. Methods:Tiger salamanders retinal slices (250 µm thick) were fixed in 4% paraformaldehyde for 17 minutes and then incubated overnight in either rabbit anti–GABA or rat anti–glycine antibody (courtesy of Dr. David Pow), followed by a CY5 labeled secondary. GABA– or glycine–positive cells were penetrated with a sharp electrode filled with 2–3 % DiO in dichloromethane, backfilled with 100% ethanol, and current (20 nA) was used to inject the DiO for 10 minutes. The cells were then imaged either with the scope–mounted camera or confocal microscopy. Results:DiO filled GABAergic amacrine cells had individual processes that radiated laterally from the soma between 25 µm and 150 µm with a mean dendritic field of 145 µm. Some GABAergic ACs were narrow field and multistratified, while others exhibited sparse branching with processes in one or multiple sublamina. Glycinergic DiO–filled amacrine cells had processes that radiated between 55 µm up to 110 µm away from the soma with a mean dendritic field of 113 µm. Some glycinergic AC processes were monostratified with sparse ramification. Several other cells showed a small tuft of dendrites near their soma and long, infrequently branching processes. Conclusions:There was no statistical difference in the lateral spread of dendrites for GABA and glycine stained cells. However none of the injected cells had processes that could be classified as wide–field. This is likely due to the limited time the DiO was allowed to infiltrate the membrane before imaging. If this time was extended we may find ACs with definitive wide field arborizations. Other constraints could be the thickness of the slices which may have truncated wide field processes. Additionally, the AC population is diverse and we certainly have not investigated all cell types.
This PDF is available to Subscribers Only