Characterization of small‐field bistratified amacrine cells in macaque retina labeled by antibodies against synaptotagmin‐2

The subthalamic nucleus (STN) is a critical excitatory signaling center within the basal ganglia circuitry. The activity of subthalamic neurons is tightly controlled by upstream inhibitory signaling centers in the basal ganglia. In this study, we used immunohistochemical techniques to firstly, visualize and quantify the STN neurochemical organization based on neuronal markers including parvalbumin (PV), calretinin (CR), SMI-32, and GAD . Secondly, we characterized the detailed regional, cellular and subcellular expression of GABA (α , α , α , β , and γ ) and GABA (R1 and R2) receptor subunits within the normal human STN. Overall, we found seven neurochemically distinct populations of principal neurons in the human STN. The three main populations detected were: (a) triple-labeled PV /CR /SMI32 ; (b) double-labeled PV /CR ; and (c) single-labeled CR neurons. Subthalamic principal neurons were found to express GABA receptor subunits α , α , β , γ , and GABA receptor subunits R1 and R2. However, no expression of GABA receptor α subunit was detected. We also found a trend of increasing regional staining intensity for all positive GABA receptor subunits from the dorsolateral pole to ventromedial extremities. The GAD interneurons showed relatively low expression of GABA receptor subunits. These results provide the morphological basis of GABAergic transmission within the normal human subthalamic nucleus and evidence of GABA innervation through both GABA and GABA receptors on subthalamic principal neurons.

Section: Methodsmentioning

confidence: 99%

GABA_A and GABA_B receptor subunit localization on neurochemically identified neurons of the human subthalamic nucleus

Song

Faull

et al. 2017

“…A recent study in the mouse retina has physiologically characterized a number of narrow-field amacrine cells and found at least 12 different types (Pang et al, 2012) but did not include the A8 amacrine cell. The bistratified A8 amacrine cell was first morphologically described in cat and was subsequently found in other mammalian species (ground squirrel: Linberg et al, 1996;rabbit: MacNeil and Masland, 1998;mouse: Badea and Nathans, 2004;Heinze et al, 2007;primate retina: Kolb et al, 1992;Neumann and Haverkamp, 2013). The A8 amacrine cell has processes in both the OFF (S1 stratum) and the ON (S4 stratum) layers of the IPL.…”

mentioning

confidence: 99%

Morphology and connectivity of the small bistratified A8 amacrine cell in the mouse retina

Lee

Meyer

Schubert

et al. 2015

Self Cite

Amacrine cells comprise ~30 morphological types in the mammalian retina. The synaptic connectivity and function of a few GABAergic wide-field amacrine cells have recently been studied, however, with the exception of the rod pathway-specific AII amacrine cell the connectivity of glycinergic small-field amacrine cells has not been investigated in the mouse retina. Here, we studied the morphology and connectivity pattern of the small-field A8 amacrine cell. A8 cells in mouse retina are bistratified with lobular processes in the ON sublamina and arboreal dendrites in the OFF sublamina of the inner plexiform layer. The distinct bistratified morphology was first visible at postnatal day 8, reaching the adult shape at P13, around eye opening. The connectivity of A8 cells to bipolar cells and ganglion cells was studied by double and triple immunolabeling experiments using various cell markers combined with synaptic markers. Our data suggest that A8 amacrine cells receive glutamatergic input from both OFF and ON cone bipolar cells. Furthermore, A8 cells are coupled to ON cone bipolar cells by gap junctions, and provide inhibitory input via glycine receptor (GlyR) subunit α1 to OFF cone bipolar cells and to ON A-type ganglion cells. Measurements of spontaneous glycinergic postsynaptic currents and GlyR immunolabeling revealed that A8 cells express GlyRs containing the α2 subunit. Taken together, the bistratified A8 cell makes very similar synaptic contacts with cone bipolar cells as the rod pathway-specific AII amacrine cell. However, unlike AII cells, A8 amacrine cells provide glycinergic input to ON A-type ganglion cells.

“…Nearly all amacrine cells contain either g-aminobutyric acid (GABA) or glycine and can be further distinguished because of their neurochemical diversity (Kalloniatis et al, 1996; for review, see Wilson and Vaney, 2008). The spatial distribution of amacrine cells across the retina has been studied in different primate species for subpopulations of GABAergic cells: tyrosine hydroxylase positive (Mariani et al, 1984), somatostatin positive (Mitrofanis et al, 1989), NADPH-diaphorase positive (Provis and Mitrofanis, 1990), cholinergic (starburst cells, Rodieck, 1989;Rodieck and Marshak, 1992), glycogen phosphorylase positive (wiry) cells (Majumdar et al, 2008), vasoactive intestinal polypeptide (VIP)-positive cells (Lammerding-K€ oppel et al, 1991), and secretagoginpositive (spiny cells, Weltzien et al, 2014); and for subpopulations of glycinergic cells: calretinin-positive AII amacrine (W€ assle et al, 1995;Mills and Massey, 1999;Kolb et al, 2002), parvalbumin-positive knotty type 2 cells (Klump et al, 2009), and synaptotagmin-2-positive A8 cells (Neumann and Haverkamp, 2013). The extent to which the proportion of different amacrine cell types changes between the central and peripheral retina in primate is, however, currently unknown.…”

mentioning

confidence: 99%

Analysis of bipolar and amacrine populations in marmoset retina

Weltzien

Percival

Martin

2014

About 15 parallel ganglion cell pathways transmit visual signals to the brain, but the interneuron (bipolar and amacrine) populations providing input to ganglion cells remain poorly understood in primate retina. We carried out a quantitative analysis of the inner nuclear layer in the retina of the marmoset (Callithrix jacchus). Vertical Vibratome sections along the horizontal meridian were processed with immunohistochemical markers. Image stacks were taken with a confocal microscope, and densities of cell populations were determined. The density of flat midget bipolar cells fell from 15,746 cells/mm(2) at 1 mm (8 deg) to 7,827 cells/mm(2) at 3 mm (25 deg). The rod bipolar cell density fell from 8,640 cells/mm(2) at 1 mm to 4,278 cells/mm(2) at 3 mm, but the ratio of the two bipolar cell types did not change with eccentricity. The amacrine cell density ranged from 30,000 cells/mm(2) at 8 deg to less than 15,000 cells/mm(2) at 25 deg, but throughout the retina, the ratio of glycinergic to γ-aminobutyric acid (GABA)ergic to amacrine cells remained relatively constant. The fractions of rod bipolar, cone bipolar, amacrine, Müller, and horizontal cells of all cells in the inner nuclear layer were comparable in central and peripheral retina. Marmosets had lower proportions of midget bipolar and rod bipolar in comparison with macaque. These differences were correlated with differences in rod and cone densities between the two species and did not reflect fundamental differences in the wiring between the two species.