Expression of the γ-Aminobutyric Acid (GABA) Plasma Membrane Transporter-1 in Monkey and Human Retina

Abstract

GAT-1 in primate retinas is expressed by amacrine and displaced amacrine cells. The predominant expression of GAT-1 in the inner retina is consistent with the idea that GABA transporters influence neurotransmission and thus participate in visual information processing in the retina.

Histamine receptors of cones and horizontal cells in Old World monkey retinas

“…commun., Sigma-Aldrich technical support). It reproduced the pattern of labeling described previously using tyrosine hydroxylase antibodies in primate retinas; that is, it labeled a type of wide-field amacrine cell (Casini et al, 2006). …”

Guinea pig horizontal cells express GABA, the GABA‐synthesizing enzyme GAD65, and the GABA vesicular transporter

“…Preadsorption of this antibody with the rat GAT-1 588–599 peptide that was used for immunization at concentrations of 10 −5 to 10 −7 M eliminated GAT-1 immunostaining in mouse, rat, and monkey retina and brain sections (Ikegaki et al, 1994; Honda et al, 1995; Johnson et al, 1996; Conti et al, 1998; Casini et al, 2006; Guo et al, 2009). GAT-1 immunostaining in rat retinal sections was not affected by preadsorption of the GAT-1 antibody with the C-terminus GAT-2 594–602 (RLTELESNC) or GAT-3 607–627 (CEAKVKGDGTISAITEKETHF) peptides at concentrations of 10 −5 to 10 −7 M (Johnson et al, 1996).…”

“…A GAT reportedly mediates GABA release from retinal horizontal cells in fish and amphibians (Schwartz, 1982; Yazulla and Kleinschmidt, 1982, 1983; Schwartz, 1987, 2002; Attwell et al, 1993). However, in the mammalian retina, there is doubt regarding the hypothesis that GABA is released from horizontal cells by a plasma membrane transporter, because currently known GAT isoforms (GAT-1, GAT-2, and GAT-3) are not expressed by horizontal cells (Brecha and Weigmann, 1994; Durkin et al, 1995; Honda et al, 1995; Johnson et al, 1996; Hu et al, 1999; Casini et al, 2006; Guo et al, 2009). Furthermore, mammalian horizontal cells do not accumulate GABA and GABA analogs, as would be expected if a functional GAT were expressed by these cells (Neal and Iversen, 1972; Bruun and Ehinger, 1974; Marshall and Voaden, 1975; Cunningham et al, 1981; Agardh and Ehinger, 1982, 1983; Blanks and Roffler-Tarlov, 1982; Wässle and Chun, 1989).…”

Transporters and receptors in the posterior segment of the eye

“…Table 5.1 lists the expression of infl ux transporters in posterior ocular tissues and in cell culture models in vitro. Glucose transporters D -Glucose, DHA ARPE-19, human retina (nerve fi ber layer, the ganglion and photoreceptor cell bodies, the capillaries and the RPE), TR-iBRB2, rat retina [6], [8], [10], [13] Nucleoside transporters Adenosine TR-iBRB2, ARPE-19, rabbit retina [17], [18] Creatine transporters Creatine TR-iBRB2, rat retina, human inner retinal blood vessels and retinal pigment epithelium [20], [21] Oligopeptide transporters Dipeptides, tripeptides, cephalosporins Bovine RPE, HRPE, ARPE-19, human retina/choroid [23], [25] Taurine transporter Taurine, GABA TR-iBRB2, ARPE-19, RGC-5, rMC1 [32], [34] Large neutral amino acid transporters (System L) Phenyl alanine, leucine, tyrosine TR-iBRB2, ARPE-19 [37], [39] Glutamate transporters L -glutamate Rat retina, ARPE-19, D407 [43], [45], [47] Cystine-glutamate exchanger Cystine, glutamate ARPE-19, TR-iBRB2, TR-MUL5, rod and cone photoreceptors in the rat, cow, chicken and monkey retina [51], [52], [53], [54] GABA transporters GABA Human retina, rat retina [57], [58] Monocarboxylate transporters Lactate, pyruvate, ketone bodies Rat neural retina, mouse RPE and choroid plexus, rat Müller cells and glial cells, ARPE-19 [62], [63], [65], [66], [68], [69] Infl ux transporters present in posterior ocular tissues and cell lines Table 5.1 Organic anion transporters Antibiotics, non-steroidal anti-infl ammatory drugs, and anti-HIV agents Rat retina, interface between the pigment epithelium and the photoreceptor outer segment [79], [80] Organic ani...…”

“…Several studies have established the expression of different subtypes of GATs (GAT-1, GAT-2 and GAT-3) in retinal tissues. In human and monkey retina, Casini et al [57] studied the expression of GAT-1 by fl uorescence and confocal microscopy. GAT-1 expression was abundant in both species' retinas with similar distribution patterns.…”