Retinal Muller cells

M. Tomi, T. Funaki, H. Abukawa, K. Katayama, T. Kondo, S. Ohtsuki, M. Ueda, M. Obinata, T. Terasaki, and K. Hosoya. Expression and regulation of L-cystine transporter, system Z(T, in the newly developed rat retinal Muller cell line (TR-MUL). Glia 43 208-217 (2003). 

Sagar SM, Edwards RH, Sharp FR- 1991. Epidermal growth factor and Transforming growth factor alpha induce c-fos gene expression in retinal Muller cells in vivo. J Neurosci Res 29 549-559. 

Presence of mitogen-activated protein kinase in retinal Muller cells and its neuroprotective effect ischemia-reperfusion injury. Neuroreport 13 2103-2107. 

Na+-independent and also Na+-dependent GSH transport systems have been found in lens epithelium, retinal Muller cells, brain endothehal cells and astrocytes [82-84]. The Na+-dependent transport mediates GSH uptake,whereas the Na+-independent carrier appears to be mainly involved in GSH efflux. It is worth noting that these transport systems allow GSH transport across the blood-brain barrier in vivo [85]. 

Kannan R, Bao Y, Wang Y, Sarthy VP, Kaplowitz N (1999) Protection from oxidant injury by sodium-depen dent GSH uptake in retinal Muller cells. Exp Eye Res 68 609-16 Kannan R, Chakrabarti R, Tang D, Kim KJ, Kaplowitz N (2000) GSH transport in human cerebrovascular endothelial cells and human astrocytes evidence for luminal localization of Na -dependent GSH transporter in HCEC. Brain Res 852 374-82 Kannan R, Kuhlenkamp JF, Ookhtens M, Kaplowitz N (1992) Transport of glutathione at blood-brain barrier of the rat inhibition by glutathione analogs and age-dependence. J Pharmacol Exp Ther 263 964-70... 

Figure 14.2 Phase contrast microscopic images of conditionally immortalized cells forming the inner blood-retinal barrier (A) and time-course of [3H] adenosine uptake by TR-iBRB cells (B). A Conditionally immortalized rat retinal capillary endothelial cell line TR-iBRB, retinal pericyte cell line TR-rPCT and Muller cell line TR-MUL. B The [ H]adenosine (14 nM) uptake was performed at 37°C in the presence (closed circle) or absence (open circle) of Na+.

Sites of expression Ocular and extraocular photoreceptors Retinal pigment epithelium and Muller cells Ocular and extraocular photoreceptors... 

Li 1, Patil RV, Verkman AS (2002) Mildly abnormal retinal function in transgenic mice without Muller cell aquaporin-4 water channels. Invest Ophthalmol Vis Sci 43 573—579 Ma T, Yang B, Gillespie A, Carlson El, Epstein Cl, Verkman AS (1997) Generation and phenotype of a transgenic knockout mouse lacking the mercurial-insensitive water channel aquaporin-4. 1 Clin Invest 100 957-962... 

Keywords Amacrine cell Bipolar cell Cone Fovea Horizontal cell Muller cells Photoreceptor Retina Retinal ganglion cell Rod... 

Fischer AJ, Reh TA (2003) Potential of Muller glia to become neurogenic retinal progenitor cells. Glia 43 70-76. 

Muller cells are major sites for the uptake and removal of neurotransmitters, most notably glutamate and GABA. Glutamate transport into neurons is smaller and slower than transport into Muller cells and thus uptake into Muller cells is the principal mechanism responsible for the initial removal of extracellular glutamate following synaptic activation (Pow, 2001). In addition to neurotransmitter transporters, Muller cells possess neurotransmitter receptors and can release neuroactive substances (e.g., ATP) (Newman, 2004). Thus, activity of retinal neurons can influence Muller cells and Muller cell activity can in turn influence adjacent neurons. 

Analysis of the neuron to Muller cell ratio shows that it is not randomly distributed, but peaks at 16 or 32 neurons per Muller cell. Moreover, the number of Muller cells correlates with the number of photoreceptors (since most of the photoreceptors are rods, it correlates with the number of rods) rather than the number of gangUon cells (Reichenbach et al., 1994b). Comparison of the ratios of various retinal cells in different species suggests that the phylogeny and the ontogeny of these retinas can be explained by accounting for the number of divisions of progenitor cell (Reichenbach and Robinson, 1995). 

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