Separation-Based Methods Combined With Microdialysis Sampling for Monitoring Neurotransmitters and Drug Delivery to the Brain

Sensitive targeted methods for brain metabolomic studies in microdialysis samples

“…Temporal resolution can be crucial to obtain real-time information regarding neuromessengers as changes typically occur on a millisecond-time scale and relies on both the volume of sample required by and the sensitivity of the selected analytical technique. However, over the years highly sensitive analytical techniques have been developed, allowing to reduce the sampling time [35,37,38]. Additionally, spatial resolution of the microdialysis probe (i.e.…”

“…At last, the concentration of neurochemicals in dialysate does not correspond with their actual concentration in the extracellular brain fluid, since often no equilibrium is obtained between the tissue of interest and the microdialysate. This is referred to as the relative recovery and usually it does not exceed 40% [31,38]. Over the years, efforts have been made to tackle some of the drawbacks of microdialysis.…”

“…This implies that a decrease in perfusion flow rate will provoke an increase in relative recovery, especially for compounds with low extracellular concentration or diffusivity [31]. The perfusion flow rates generally applied during microdialysis (0.3 to 3 µL/min) imply that usually no equilibrium is established between the tissue of interest and the sampled microdialysate, leading to a difference in concentration between the dialysate and the extracellular fluid [38].…”

“…However, to achieve an acceptable relative recovery, the molecular weight of the compound should not exceed one fourth of the molecular weight cut-off of the membrane [30]. Besides the molecular weight cutoff, the dimensions and the chemical composition of the membrane will also influence analyte diffusion and consequently analyte recovery [38].…”

A review of microdialysis coupled to microchip electrophoresis for monitoring biological events

“…In this study, the production of nitrite after a nitroglycerin perfusion was monitored on-animal using subcutaneous microdialysis sampling coupled to the device detailed in reference [110]. Additionally, we are currently developing an on-line microdialysis-microchip electrophoresis flow-gated device for the easy integration of carbon electrodes [146]. This device will be employed to monitor catecholamines in freely-roaming, untethered sheep and measure correlations between neurotransmitters and behavior (Fig.…”