3P-20 PDF
Visualization of amine neurotransmitters by matrix-free laser desorption/ionization imaging mass spectrometry using a photocleavable derivatizing reagent
Imaging mass spectrometry (IMS) can construct images of molecules in tissue samples. Lipids, proteins and easy-to-ionize neurotransmitters such as acetylcholine in tissue sections have already been visualized. The molecular species targeted for measurement keeps increasing. Nonetheless, many small mass molecules are still difficult to detect by IMS.
In this work, we aimed to develop a new chemical derivatization method for amines acting as neurotransmitters in biological specimens for IMS analysis. 4-[3,5-Dimethyl-4-(4-nitrobenzyloxy)phenyl]-4-oxobutyric acid succinimidyl ester (DNPO-SE) can reacts with amines, which has developed as a photocleavable compound for laser desorption/ionization mass spectrometry (LDI-MS). We have extended the application of DNPO-SE to imaging mass spectrometry (IMS) for visualizing amine neurotransmitters in biological specimens. Using DNPO-SE as a derivatization reagent enabled us to simultaneously derivatize eight amines. As a result, we were able to simultaneously visualize the distribution of derivatized some amino acids in a single mouse brain tissue section. Interestingly, each of the amines showed a different spatial distribution. Using a photocleavable molecule such as DNPO-SE as the derivatization reagent enabled us to successfully analyze mouse brain sections by matrix-free LDI-IMS. The method reported here can be used to analyze any chemically reactive amines and is simpler and quicker than current matrix-assisted IMS methods.