Immunocytochemical analysis of GABA‐positive and calretinin‐positive horizontal cells in the tiger salamander retina

Abstract

By using immunocytochemical techniques, we demonstrate that there are two distinct, nonoverlapping populations of horizontal cells (HCs) in the tiger salamander retina: GABA-positive cells account for about 72% and GABA-negative (calretinin-positive) cells account for 28% of the total HC somas. The calretinin-positive HCs have relatively sparse and thick dendrites: soma diameter of 19.72 +/- 0.29 microm, and soma density of 140 +/- 13 cells/mm(2), morphological features very much like the A-type HCs described in the accompanying article. The GABA-positive HCs have thinner dendritic and coarse axon-terminal-like processes of higher density: soma diameter of 18 +/- 0.18 microm, and soma density of 364 +/- 18 cells/mm(2), features that very much resemble the B-type HCs and B-type HC axon terminals in the accompanying article. By using double and triple immunostaining techniques we found that only 18% of the non-GABAergic HC dendritic clusters contact rods, whereas the remaining 82% of the dendritic clusters contact cones. This is consistent with the physiological finding in the accompanying article that the A-type HCs are cone-dominated. On the other hand, 32% of GABAergic HC dendrites contact rod pedicles and 68% contact cone pedicles, consistent with the physiological finding that B-type HCs and B-type HC axon terminals receive mixed rod/cone inputs. Detailed confocal microscope analysis shows that 4% rods, 6% principal double cones/single cones, and 100% accessory double cones contact calretinin-positive HCs, and 79% rods, 100% principal double cones, 14% accessory double cones, and 82% single cones contact GABAergic HCs. These results suggest that GABAergic and non-GABAergic HC input/output synapses differ and they may mediate different functional pathways in the outer retina.

Tryptophan Hydroxylase and Serotonin Receptors 5-HT1A, 5-HT2A, 5-HT3A, 5-HT4, 5-HT5A, 5-HT6 and 5-HT7 in Frog and Turtle Retina: an Immunofluorescence Study

“…Comparing it to the CR staining, an increase of the number of the bipolar cells stained can be noticed. Our data are in agreement with the data obtained by other authors on the same type [43] or on closely related type of retina [44]. In our double labeling experiments we combined Calbindin antibody (red) and TrypH one (green), the results of which are represented in Fig.…”

“…For the purpose of screening the cell classes, we chose two antisera towards calretinin and calbindin, belonging to the calcium binding proteins: Their distribution in the retinas of the different species is studied by a great number of authors [43,44,45]. Photomicrographs representing the calretinin (CR) and calbindin (CB) distribution in our experiments are shown in Fig.…”

Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses

“…Nonmammals have between two and five types of horizontal cells and only one type of cone-driven horizontal cell (H 1 ) is GABAergic in fish and turtle retina ([59–61]; review: [62]). In amphibian retina H 1 GABAergic cells receive mixed rod-cone input [63]. GABAergic horizontal cells have also been described in some mammalian species ( rodent : [47, 64, 65]; cat : [17, 25, 32]; rabbit : [47, 51, 66]; monkey : [29, 67, 68]) (Figure 1).…”

A half century of experimental neuroanatomical tracing

“…In this particular application, Neurobiotin has enjoyed throughout the years a steady popularity. It is being applied both in mammals (rat, rabbit; as exemplified recently by Ruigrok et al, 2011), amphibians (Zhang et al, 2006), and invertebrates (Fan et al, 2005) (see section 5).…”