Combined electrochemistry and mass spectrometry imaging to interrogate the mechanism of action of modafinil, a cognition-enhancing drug, at the cellular and sub-cellular level. (2nd July 2021)

• Record Type: Journal Article
• Authors: Ranjbari, Elias; Philipsen, Mai H.; Wang, Zhaoying; Ewing, Andrew G.
• Is Part Of: QRB discovery. Volume 2(2021)
• Publication Date: 2021-07-02
• Subjects: Cognition-enhancing drug -- modafinil -- intracellular vesicle impact electrochemical cytometry -- single-cell amperometry -- time-of-flight secondary ion mass spectrometry; Biophysics -- Periodicals; 571.4
• DOI: 10.1017/qrd.2021.4
• Languages: English
• ISSNs: 2633-2892

Abstract

Abstract: ( A ) Microscope view during the intracellular vesicle impact electrochemical cytometry experiment (scale bar = 20 μm). ( B ) Normalised frequency histogram for the number of molecules stored in vesicles in control (blue) and modafinil-treated cells (red). The distribution fits are shown for control cells with a dashed line and modafinil-treated cells with a solid line. ( C ) Average of the number of molecules stored per vesicle in PC12 cells treated without (control) or with 10 μM modafinil. Number of analysed cells: control cells (15 cells) and modafinil-treated cells (18 cells). The results were compared by a two-tailed Mann–Whitney rank-sum test, * p < 0.05, ** p < 0.01 and *** p < 0.001. Abstract: Modafinil is a mild psychostimulant-like drug enhancing wakefulness, improving attention and developing performance in various cognitive tasks, but its mechanism of action is not completely understood. This is the first combination of amperometry, electrochemical cytometry and mass spectrometry to interrogate the mechanism of action of a drug, here modafinil, at cellular and sub-cellular level. We employed single-cell amperometry (SCA) and intracellular vesicle impact electrochemical cytometry (IVIEC) to investigate the alterations in exocytotic release and vesicular catecholamine storage following modafinil treatment. The SCA results reveal that modafinil slows down the exocytosis process so that, the number of catecholamines released per exocytotic event is enhanced in the modafinil-treated cells. Also, IVIEC results offer an upregulation effect of modafinil on the vesicular catecholamine storage. Mass spectrometry imaging by time-of-flight secondary ion mass spectrometry (ToF-SIMS) illustrates that treatment with modafinil reduces the cylindrical-shaped phosphatidylcholine at the cellular membrane, while the high curvature lipids with conical structures such as phosphatidylethanolamine and phosphatidylinositol are elevated after modafinil treatment. Combining the results obtained by SCA, IVIEC and ToF-SIMS suggests that modafinil-treated cells release a larger portion of their vesicular content at least in part by changing the lipid composition of the cell membrane, suggesting regulation of cognition.