Overview of Brain Microdialysis

Abstract

The technique of microdialysis enables sampling and collecting of small-molecular-weight substances from the interstitial space. It is a widely used method in neuroscience and is one of the few techniques available that permits quantification of neurotransmitters, peptides, and hormones in the behaving animal. More recently, it has been used in tissue preparations for quantification of neurotransmitter release. This unit provides a brief review of the history of microdialysis and its general application in the neurosciences. The authors review the theoretical principles underlying the microdialysis process, methods available for estimating extracellular concentration from dialysis samples (i.e., relative recovery), the various factors that affect the estimate of in vivo relative recovery, and the importance of determining in vivo relative recovery to data interpretation. Several areas of special note, including impact of tissue trauma on the interpretation of microdialysis results, are discussed.Step-by-step instructions for the planning and execution of conventional and quantitative microdialysis experiments are provided.

Brain interstitial fluid glutamine homeostasis is controlled by blood–brain barrier SLC7A5/LAT1 amino acid transporter

“…27 Sensor detection methods, which have high accuracy, are only applicable for a few analytes while sampling can be used to broadly screen multiple substances (such as AAs). Direct sampling either involves a ''push-pull'' method or a very low flow extraction.…”

“…Instead, fluid is perfused through a semi-permeable microdialysis probe to extract brain solutes. 27 Due to technical limitations most microdialysis studies avoid reporting quantitative data instead normalizing results from experimental manipulations relative to baseline controls. However, two accepted methods for quantification ''no-net-flux'' and the ''extrapolation to zero-flow'' (or ''Flow-rate'') have been developed.…”

“…However, two accepted methods for quantification ''no-net-flux'' and the ''extrapolation to zero-flow'' (or ''Flow-rate'') have been developed. 27 The ''no-netflux'' method requires a series of perfusions with different concentrations of the substance of interest. The brain concentration is determined as the concentration of the target for which no net exchange occurs during perfusion into the brain.…”

“…27 Flow-rate experiments were performed twice: initially with aCSF perfusate, and repeated with aCSF þ100 mM NLeu. K 0 for NLeu vs. other AAs of interest was determined in vitro and found comparable.…”

A model for simulation and patient-specific visualization of the tissue volume of influence during brain microdialysis

“…Microdialysis is a method for monitoring of the local biochemical environment in a region of interest, and is a commonly used technique for sampling biochemical substances in the brain [1]. The method uses a catheter, mimicking a blood capillary, which can be inserted into a variety of tissues.…”