Detection and imaging of L-glutamate released from mouse-brain slices withan enzyme-based membrane

A new and simple method for detecting and color imagine of L-glutamate rele ased in mouse-brain slices is described based on an enzyme-coupling reactio n. The method utilizes L-glutamate oxidase (GluOx) and horseradish peroxida se (HRP) immobilized in a bovine serum albumin (BSA)-glutaraldehyde matrix on a poly-L-lysine-coated glass cover slip. The enzymes are spontaneously a nd continuously supplied from the membrane into an extracellular solution o f the brain slice placed on the membrane after dipping in a redox substrate (DA-64). The Bindschedler's Green (BG) converted from the DA-64 by the enz yme reaction gives green signals in the brain slice. which are related to t he concentration of L-glutamate released in its regions. The first examples of color images for the spatial distribution of L-glutamate in the regions of adult mouse brain slices are demonstrated. The regions where the intens e green signals were observed matched the reported distribution of mRNAs en coding the NMDA receptor in the mouse-brain slice.