In Vivo Microdialysis
In vivo brain microdialysis has received widespread application as a sampling technique for capturing neurochemical release in discrete areas of the brain. The idea of microdialysis is to implant a small semi-permeable dialysis membrane in tissue and perfuse the sealed system with an artificial cerebral spinal fluid that mimicks the brains extracellular solution (Figure 1). Molecules present in the extracellular space surrounding the membrane diffuse into the probe as a result of the concentration gradient, and the dialysate concentration of these substances can subsequently be quantified using mass spectrometry.
Molecules collected by in vivo microdialysis come from the extracellular space and provide an index of extracellular signalling competent substances including neurotransmitters, bioactive lipids, and neuropeptides [1-3]. Microdialysis allows sampling from discrete brain regions, and experiments are typically performed in active animals during behavioral paradigms. Because samples may be collected for several hours, it is possible to temporally correlate molecular changes in dialysate with specific behavioral or pharmacological events.
Figure 1. Schematic of in vivo microdialysis probe setup, neurochemical diffusion, and sample collection.
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