ISSN:
1432-2013
Keywords:
Rat
;
Hippocampus
;
Hilus
;
Glutamate
;
Kainate
;
Patch-clamp in situ
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Glial cells in the hilus of the dentate gyrus of the rat were investigated using the patch-clamp technique in acute slices of the hippocampal formation. According to their voltage-gated current patterns, two classes of glial cells — putative astrocytes and presumed glial precursor cells — were apparent. The glutamate receptor agonists kainate, glutamate, and α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) evoked inward currents at a holding potential of −70 mV in astrocytes and presumed glial precursor cells. Inward currents could also be induced in nucleated patches, indicating a direct action on glial receptors. In presumed hilar glial precursor cells, 6,7-dinitroquinoxaline-2,3-dione (DNQX; 10 μM) blocked the kainate-induced current, while it was partially inhibited by Zn2+ (2 mM) and Evans Blue (10 μM). Cyclothiazide (100 μM), in contrast, potentiated this current, indicating the presence of AMPA receptors. In 90% of the presumed glial precursor cells the excitatory amino-acid-evoked current voltage (I/V) relations were linear or outwardly rectifying and reversed close to 0 mV, which is characteristic for non-specific cation channels. To determine the permeability to Ca2+, I/V relations were determined in a Na+-free solution containing 40 mM Ca2+ and showed reversal potentials of a wide variation ranging from −63 mV to + 1 mV with corresponding P Ca/ P Cs permeability ratios of between 0.09 and 2.10. Statistical analysis revealed that the permeability to Ca2+ significantly decreased with an advance in age (r=−0.596; n=21; P〈0.01). These data suggest that the Ca2+ influx mediated by the activation of AMPA receptors expressed in presumed hilar glial precursor cells is dependent on the developmental stage.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00410197
