Distribution of GABA with Mass Spectrometry Imaging
Based on litterature, we developed a protocol to investigate distribution and quantification of GABA. We used the 4-hydroxy-3-methoxycinnamaldehyde (CA) as a derivatisation reagent to specifically identify GABA on brain tissue and enhance its sensitivity. Thanks to this derivatization strategy, we are able to detect and precisely locate GABA on brain tissue using MALDI-FTICR analysis. For this purpose, it is important to dierentiate GABA from endogenous isoforms that have the same exact mass in the literature. Therefore, specific identification of GABA was developed at the same time as the derivati-sation strategy. Indeed, out of 6 isoforms, 2 of them could be confused with GABA aer derivatisation: the 3-aminobutyric acid (BABA) and the 3-amino-isobutyric acid (BAIBA).
To detect GABA on brain tissue, the derivatisation strategy has been used. The reaction between GABA and the derivatisation reagent has increased the signal due to additional charge. Moreover, the dierentiation between isoforms and GABA was, therefore, made though specific fragmentation analysis of derivatisated GABA with the 4-hydroxy-3-methoxycinna-maldehyde. Images of GABA distribution were successfully obtained with MALDI-FTICR-MS analyses to performed locali-sation of GABA on the grey matter. Moreover, distinction between grey and white matter allow visualising the arbor vitae in cerebellum with only slight delocalisation induce by the derivatization method. This strategy allow the localisation on brain tissue of the major inhibitory neurotransmitter in the Central Nervous System and could provide a better unders-tanding of its involvement in neural and mood disorders as bipolar disorder, schizophrenia, Huntington and Parkinson diseases.