Patch sensor detection of glutamate release evoked by a single electrical shock

Abstract

We tried to detect minimal stimulation-induced glutamate overflow from the surface of a hippocampal slice using an outside-out patch electrode excised from pyramidal cell membranes. The amplitude of the stimulation-induced patch current was dependent on the distance between the slice surface and the tip of patch sensor. The current-voltage relations of the stimulation-induced patch current were similar to those of the current evoked puff by application of L-glutamate to the patch. This indicates that the stimulation-induced patch current was produced by glutamate released from presynaptic terminals, and thus this technique may be useful in the study of transmitter release evoked by minimal electrical stimulation in brain slices.

Real-time monitoring of extracellular l-glutamate levels released by high-frequency stimulation at region CA1 of hippocampal slices with a glass capillary-based l-glutamate sensor

“…Combination of electrophysiological and sensor techniques provides a useful, often essential information on the targeted neuronal events. Recordings of L-glutamate currents at electrochemical sensors have been reported by using different type of electrodes such as an excised patch technique [28,23,22,20,11,37], a whole-cell technique using astrocyte transporter currents [21,12], and an in vivo method using a dialysis electrode [13]. Enzyme-based sensors have also been extensively used for in vivo and in vitro monitoring of extracellular L-glutamate [7,26,35,34,39,38,32,17,33].…”

Pore-forming Compounds as Signal Transduction Elements for Highly Sensitive Biosensing

“…A patch-clamp sensor (abbreviated as a patch sensor) is constructed by excising a patch membrane. The natural receptor-based sensors have been exploited by several authors, [124][125][126][127][128][129] including us. 130 The spatial resolution of a patch sensor (diameter <2 μm) is better than that (approximate 10 μm) of enzyme sensors.…”

Implantable Patch Sensor for l-Glutamate in Hippocampal Slices

“…Patch sensors for L-glutamate have been exploited by utilizing L-glutamate-sensitive receptors, such as N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoazole propionic acid (AMPA) receptors. [7][8][9][10][11][12][13] The spatial resolution of patch sensors (diameter <2 μm) is better than that (approximate 10 μm) of enzyme sensors. The detection limit to L-glutamate in a bath solution is at the sub-μM to μM level.…”

“…Hence, patch sensors so far reported detect L-glutamate that diffuses out of the slice. 8,9,[11][12][13] To the best of our knowledge, one example of an implanted patch sensor has been reported, in which an excised patch sensor was implanted in region dentate gyrus (DG) of submerged hippocampal slices for monitoring L-glutamate release. 10 On the other hand, in electrophysiological studies, a different form of experimental chambers has been designed, which provides an oxygenated environment by running an ACSF underneath a slice and passing humidified oxygenated gas over the slice.…”

“…1,2 On the other hand, natural receptor-based sensors, i.e., patch-clamp sensors (abbreviated as a patch sensor), have also been exploited by utilizing excised membranes containing receptor ion channels, including glutamate receptor ion channels (GluRs) that sense L-glutamate in brain slices, 3 or by clamping a whole cell with a glass pipet, 1,[4][5][6][7][8] which allows one to measure ion currents of all channels in the cell membrane. In contrast to the whole-cell recording, an excised membrane-based patch sensor is independent from the activity of a neuronal system to be measured.…”