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In Vivo Real-Time Monitoring System Using Probe Electrospray Ionization/Tandem Mass Spectrometry for Metabolites in Mouse Brain

Zaitsu, Kei, Hayashi, Yumi, Murata, Tasuku, Yokota, Kazumi, Ohara, Tomomi, Kusano, Maiko, Tsuchihashi, Hitoshi, Ishikawa, Tetsuya, Ishii, Akira, Ogata, Koretsugu, Tanihata, Hiroshi
Analytical chemistry 2018 v.90 no.7 pp. 4695-4701
agonists, cannabinoids, cerebrum, energy metabolism, ionization, metabolites, mice, monitoring, spectrometers, tandem mass spectrometry
Recent improvements in ambient ionization techniques combined with mass spectrometry has enabled to achieve real-time monitoring of analytes of interest, even for biogenic molecules in living animals. Here, we demonstrate a newly developed system for in vivo real-time monitoring of metabolites in a living mouse brain. It consists of a semiautomated manipulation system and a unique probe electrospray ionization unit, which uses an extremely thin solid needle (tip dia.: 700 nm) for direct sampling and ionization, coupled to a conventional tandem mass spectrometer. The system successfully monitored 8 cerebrum metabolites related to central energy metabolism in an isoflurane-anesthetized mouse in real time with a 20 s interval. Moreover, our system succeeded in capturing dynamics of energy metabolism in a mouse administered with cannabinoid type-1 receptor agonist, which is known to disrupt cerebrum energy metabolism. The present system now opens the door to the next stage of cutting-edge technique in achieving in vivo real-time monitoring.