Chemical sampling neurotransmitter

A variety of different methodologies has been employed to investigate the neurotransmitter systems involved in control of behavioral states. Biochemical experiments have elucidated the pathways and enzymes involved in the synthesis, degradation, release and reuptake of different neurotransmitters. Immuno-histochemical techniques have allowed the visualization of their cellular and sub-cellular distribution throughout the nervous system as well as the distribution of their receptors and uptake systems. Chemical sampling techniques, including... 

With a limited ability to sample the brain s chemicals directly, researchers have turned to other methods. As described in the sidebar on pages 82-83, proteins such as enzymes and receptors play a vital role in neurotransmitter function. Since these proteins are specific to a specific neurotransmitter, they serve as markers for its use. By attaching various molecules such as dyes, radioactive substances—which emit energetic particles or radiation—or fluorescent molecules—which emit light—to... 

The main target for microdialysis implantations is the ECF of various organs, predominantly the brain. The main objective of these studies is to find chemical correlations, as represented by measured neurotransmitter levels, to pharmaceutical, behavioral, pathological, or other stimuli. However, because of its small size a microdialysis probe allows sampling of fluids from other locations without first removing the fluid. Body fluids other than ECF to which the microdialysis technique has been applied are considered in Sections 6.3.1.1 to 6.3.I.6. 

Applied to the synthesis of Glu analogues, the creativity of the medicinal chemists seems to be unlimited. Compounds 8-18 (Fig. 15.3) represent a small sample of all the compounds that were reported. Some of the ligands show binding constants in the nanomolar range, whereas Glu itself is only in the micromolar range. This example confirms that conformational rigidification is a powerful tool when applied to neurotransmitters, and also confirms that the creativity of the medicinal chemists is endless as long as chemical pathways are at hand. " ... 

Recently, Song et al. utilized a derivatization strategy to measure the broadest range of small molecule neurotransmitters reported to date, which included several amino acids, four monoamines, ACh, adenosine, and their major metabolites [54]. Due to the inherent chemical diversity and polar nature of these compounds, all the analytes, with the exception of ACh, were derivatized with benzyl chloride to achieve efficient separation in 8-minute run times by RPLC. Derivatization also improved the sensitivity of ESI—MS/MS analysis and provided a convenient way to generate isotope-labeled internal standards for quantification with commercially available C benzoyl chloride. The LC—MS method described in this study was suitable for the simultaneous detection of all analytes of interest in low-volume dialysis samples with sufficient sensitivity and high-throughput capability to permit fast sampling rates. 

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