Astrocytes retinal

Erythrocytes from humans, birds, and rat Ehrlich ascites tumor cells astrocytes fibroblasts C67 glioma cells intestine trachea parotid MDCK cells retinal pigment epithelium frog skin HeLa cells rabbit medullary thick ascending limb Inhibition of K+ and Cl channels... 

The retina also contains three other types of gUa astrocytes, oligodendrocytes and microglia. Retinal astrocytes are located primarily in the NFL and oligodendrocytes form the myelin sheath of axons in the optic nerve. Hematopoetically derived microglia are small stellate cells that, when quiescent, associate with inner retinal blood vessels. 

During hereditary retinal degeneration, nNOS immunoreactive cells survive even when the retina is extensively degenerated (Sharma et al., 2001). In ischemic retina, expressions of all NOS isoforms have been reported to increase. Activated macrophages and other inflammatory cells that infiltrate the retina are a major source of NO produced by iNOS. In addition, retinal astrocytes and Muller cells also contribute (Neufeld et al., 2002). 

Activation of microglia by cytokines can produce NO (by iNOS) and superoxide that can diffuse into the neighboring neurones and cause damage. Microglia play an important role in retinal degeneration. In glaucoma, astrocytes in the optic nerve exhibit functional and biochemical characteristics of activation... 

Hernandez MR. 2000. The optic nerve head in glaucoma Role of astrocytes in tissue remodeling. Prog Retin Eye Res 19 297-321. 

Changes of astrocytes in retinal ageing and age-related macular degeneration. Exp Eye Res 75 601-615. 

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... 

Castillo JB, del Cerro M, Breakefield XO, et al. Retinal ganglion cell survival is promoted by genetically modified astrocytes designed to secrete brain-derived neurotrophic factor (BDNF). Brain Res 1994 647 30-36. 

L.F. (1988) N-cadherin, N-CAM and integrins promote retinal neurite outgrowth on astrocytes in vitro. J. Cell Biol. 107 1177-1187. 

Neural CAD (N-CAD) is located both on glial and neuronal cells and binds in a homophilic, calcium-dependent manner (Geiger and Ayalon, 1992). Antibodies against N-CAD inhibit the growth of retinal ganglion cell neurites on astrocytes in culture. Moreover, transfection of fibroblasts with a cDNA for N-CAD converts them from neurite-inhibitory into neurite growth-stimulating cells (Takeichi, 1990). 

DHA, the most abundant n-3 PUFA ordinarily present in tissues, is present in significant amounts in PL of retinal and neuronal membranes. It is required for the proper development and function of the nervous system, and the need for DHA is the main reason why LNA is essential. The cells of the nervous system incorporate DHA because it is more readily available than n-6 DPA, not because DHA possesses special metabolic properties. In this regard, DHA is the main product of LNA metabolism in astrocytes, whereas AA — not n-6 docosapentaenoic acid (DPA) — is the main product of LA conversion. Thus, more DHA than n-6 DPA is available in the brain although the blood supply provides considerably more n-6 PUFA precursors. 

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