Glyt‐1 expression in cultured human Müller cells and intact retinae

Abstract

In this study, we demonstrate that Müller cells cultured from human retinas are capable of strongly expressing the glycine transporter Glyt-1 as assessed by immunocytochemistry. By contrast, intact normal and pathological human retinas exhibit Glyt-1 immunoreactivity only in neurons. These data suggest that Glyt-1 expression in cultured Müller cells is an epiphenomenon associated with culturing in vitro, rather than a normal physiological or even pathophysiological phenomenon in vivo.

Evidence for creatine biosynthesis in Müller glia

“…In TR-MUL5 cells, uptake rate of glycine and L-arginine was much faster than that of D-mannitol, suggesting that some neutral and cationic amino acid transporters actively transport these amino acids. This evidence is consistent with previous reports (Pow and Crook, 1997;Gadea et al, 1999;Reye et al, 2001). Glycine transport appears to take place via Glyt-1 and/or system A in the primary cultured M€ uller cells (Gadea et al, 1999;Reye et al, 2001).…”

“…This evidence is consistent with previous reports (Pow and Crook, 1997;Gadea et al, 1999;Reye et al, 2001). Glycine transport appears to take place via Glyt-1 and/or system A in the primary cultured M€ uller cells (Gadea et al, 1999;Reye et al, 2001). L-Arginine transport may occur in retinal M€ uller glia (Pow and Crook, 1997).…”

“…L-Arginine transport may occur in retinal M€ uller glia (Pow and Crook, 1997). In contrast, Reye et al (2001) reported that Glyt-1 is not expressed in M€ uller glia in vivo. The lack of agreement between the expression of glycine transporter in the cultured M€ uller cells and M€ uller glia in vivo needs an explanation.…”

Role of Ca2+ and calmodulin‐dependent enzymes in the regulation of glycine transport in Müller glia

“…Findings from this work further support an active participation of Müller glia in the regulation of retinal neurotransmission, as it demonstrates that physiological variations in Ca 2+ concentration due to calcium‐waves in these cells (Finkbeiner 1993) may control the concentration of neuroactive compounds at synaptic sites through the differential regulation of transporter systems. Localization of GLYT1 at the inner plexiform layer (Pow and Hendrickson 1999) where retinal ganglion cells receive glycinergic synaptic inputs from amacrine cells supports this idea (Lukasiewicz and Roeder 1995), although immunocytochemical studies have failed to identify Gly transporters in Müller glia in situ (Reye et al . 2001).…”

Functional expression of the glycine transporter 1 on bullfrog retinal cones

“…Two distinct subtypes of GlyTs, GlyT1, and GlyT2, have been well defined [9]. The expression of GlyT1 has been reported in both neuronal and glial elements in the vertebrate retina [10][11][12][13]. Recent studies further show that GlyT2 exists in the amphibian retina, which could be responsible for glycine uptake [14,15].…”