Figure 8.

The GLAST promoter is active in oligodendrocytes in CNS white matter. A–C, Confocal fluorescent images of the ventral horn of the spinal cord from a P24 GLAST–DsRed/PLP–eGFP double-transgenic mouse, showing expression of DsRed by many eGFP⁺ cells (arrows). Scale bar, 50 μm. D, Whole-cell recording of glutamate transporter currents from a DsRed⁺/eGFP⁺ oligodendrocyte in the ventral horn of the spinal cord from a P21 GLAST–DsRed/PLP–eGFP double-transgenic mouse, showing responses recorded under control conditions (black trace) and in the presence of DHK (300 μm; blue trace) or TBOA (300 μm; red trace). Transporter currents were elicited in response to brief photolysis (duration shown by black trace above) of MNI–d-aspartate (500 μm). E–H, Confocal fluorescent images from the striatum from a GLAST–DsRed/PLP–eGFP double-transgenic mouse at P24 (E–G) and at P10 (H). Scale bar, 50 μm. I–K, Fluorescent image of the corpus callosum from this double-transgenic mouse, showing expression of DsRed (I) and eGFP (J) by cells in this region. The two channels have been merged in K, and several cells that express only eGFP (green circles), DsRed (red circles), or both fluorescent proteins (yellow circles) have been highlighted. Scale bar, 50 μm. L, Whole-cell recording of glutamate transporter currents from a DsRed⁺/eGFP⁺ oligodendrocyte in the corpus callosum (P26 GLAST–DsRed/PLP–eGFP mouse), showing the response under control conditions (black trace) and in the presence of DHK (300 μm; blue trace) or TBOA (300 μm; red trace). Transporter currents were elicited in response to brief photolysis (duration shown by black trace above) of MNI–d-aspartate (125 μm).