C-13/N-15-Enriched L-Dopa As A Triple-Resonance Nmr Probe To Monitor Neurotransmitter Dopamine In The Brain And Liver Extracts Of Mice

In an attempt to monitor m-level trace constituents, we applied here H-1-{C-13-N-15} triple-resonance nuclear magnetic resonance (NMR) to C-13/N-15-enriched l-Dopa as the inevitable precursor of the neurotransmitter dopamine in the brain. The perfect selectivity (to render endogenous components silent) and m-level sensitivity (700MHz spectrometer equipped with a cryogenic probe) of triple-resonance allowed the unambiguous and quantitative metabolic and pharmacokinetic analyses of administered l-Dopa/dopamine in the brain and liver of mice. The level of dopamine generated in the brain (within the range 7-76m, which covers the typical stimulated level of approximate to 30m) could be clearly monitored ex vivo, but was slightly short of the detection limit of a 7T MR machine for small animals. This work suggests that m-level trace constituents are potential targets of ex vivo monitoring as long as they contain N atom(s) and their appropriate C-13/N-15-enrichment is synthetically accessible.