Implantable patch sensor for L-glutamate in hippocampal slices.

We describe an implantable patch sensor for monitoring L-glutamate in hippocampal slices in submerged and interface preparations. This patch sensor is prepared by excising the cell membrane in the CA3 region of a hippocampal slice in a submerged preparation, and then implanted in the target neuronal region (CA1) of mouse hippocampal slices. The lifetime of the sensor was 3-8 min for the interface slice and 40-50 min for the submerged slice. The calibration of an implanted sensor can be achieved by adding an L-glutamate solution to a bath (ACSF) solution. The monitoring of L-glutamate release in the CA1 region of mouse hippocampal slices under chemical stimulation with γ-aminobutyric acid (GABA) and potassium chloride (KCl) was demonstrated.