Figure 5.

CNTF activates astrocytes and increases the level of glycosylation of GLAST in vitro. A, Treatment of striatal primary cultures of neurons and astrocytes with 50 ng/ml CNTF (C) for 96 h increases the level of expression of GFAP, vimentin, and nestin compared with vehicle (V). Vimentin is already overexpressed after a 48 h treatment with CNTF. B, CNTF-activated astrocytes labeled with GFAP and S100β antibodies are hypertrophic and have enlarged processes in culture. The pattern of expression of MAP2, a component of neuronal dendrites, is not altered by CNTF treatment (B). C, CNTF increases the apparent molecular weight of GLAST in culture. This effect is more prominent after a 96 h treatment. D, CNTF also changes the pattern of labeling of GLAST, which appears less diffuse. E, At higher magnification, larger clusters are visible along nestin-positive processes in CNTF-activated astrocytes (arrowhead) compared with vehicle treated astrocytes. After treatment with methyl-β-cyclodextrin (MBCD), these clusters are lost and GLAST becomes evenly distributed at the astrocytic membrane (arrow). Scale bars: B, 50 μm; D, 20 μm; E, 5 μm.