Brain Advance Access published online on August 25, 2005
Brain, doi:10.1093/brain/awh619
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1 Department of Physiology, University College London, London, UK; Present address: Department of Cell Physiology, University of Leicester, Leicester, UK
* To whom correspondence should be addressed. Despite lacking N-methyl-D-aspartate receptors, cerebellar Purkinje cells are highly vulnerable to ischaemic insults, which lead them to die necrotically in an
Received February 6, 2005
Revised June 7, 2005
Accepted July 19, 2005
Article
The electrical response of cerebellar Purkinje neurons to simulated ischaemia
2 Department of Physiology, University College London, London, UK; Present address: Neurological Sciences Institute, Oregon Health and Science University, Beaverton, USA
3 Present address: Neurological Sciences Institute, Oregon Health and Science University, Beaverton, USA
4 Department of Physiology, University College London, London, UK
David Attwell, E-mail: D.Attwell{at}ucl.ac.uk
Abstract 
-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor-dependent manner. To investigate the electrical events leading to this cell death, we whole-cell clamped Purkinje cells in cerebellar slices. Simulated ischaemia evoked an initial hyperpolarization of Purkinje cells by 8.5 mV, followed by a regenerative ‘anoxic depolarization’ (AD) to -14 mV. The AD was prevented by glutamate receptor blockers. In voltage-clamp mode, we used the cells' glutamate receptors to sense the rise of extracellular glutamate concentration induced by ischaemia, with GABAA and GABAB receptors blocked and Cs+ as the main pipette cation. Ischaemia induced a small (<500 pA) slowly developing inward current in Purkinje cells, followed by a sudden large inward ‘AD current’ (
6 nA) which was largely prevented by blocking AMPA receptors. Removing extracellular calcium reduced the large glutamate-mediated current by 70% at early times (after 10 min ischaemia), but had no effect at later times (15 min). Blocking the operation of glutamate transporters, by preloading cells with the slowly transported glutamate analogue PDC (L-trans-pyrrolidine-2,4-dicarboxylate), reduced the current by 88% at early and 83% at later times. In Purkinje cells in slices from mice lacking the glial glutamate transporters GLAST or GLT-1, the ischaemia-evoked AD current was indistinguishable from that in wild-type slices. These data suggest that, in cerebellar ischaemia, the dominant cause of the electrophysiological dysfunction of Purkinje cells is an activation of Purkinje cell AMPA receptors. The glutamate activating these receptors is released both by exocytosis (at early times) and by reversal of a glutamate transporter, apparently in neurons.
*These authors contributed equally to this work
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