Simultaneous Sensing of H 2 S and ATP with a Two-Photon Fluorescent Probe in Alzheimer's Disease: toward Understanding Why H 2 S Regulates Glutamate-Induced ATP Dysregulation.

Energy deprivation and reduced levels of hydrogen sulfide (HS) in the brain is closely associated with Alzheimer's disease (AD). However, there is currently no fluorescent probe for precise exploration of both HS and adenosine triphosphate (ATP) to directly demonstrate their relationship and their dynamic pattern changes. Herein, we developed a two-photon fluorescent probe, named AD-3, to simultaneously image endogenous HS and ATP from two emission channels of fluorescent signals in live rat brains with AD. The probe achieved excellent selectivity and good detection linearity for HS in the 0-100 μM concentration range and ATP in the 2-5 mM concentration range, respectively, with a detection limit of 0.19 μM for HS and 0.01 mM for ATP. Fluorescence imaging in live cells reveals that such probe could successfully apply for simultaneous imaging and accurate quantification of HS and ATP in neuronal cells. Further using real-time quantitative polymerase chain reaction and Western blots, we confirmed that HS regulates ATP synthesis by acting on cytochrome C, cytochrome oxidase subunit 3 of complex IV, and protein 6 of complex I in the mitochondrial respiratory chain. Subsequently, we constructed a high-throughput screening platform based on AD-3 probe to rapidly screen the potential anti-AD drugs to control glutamate-stimulated oxidative stress associated with abnormal HS and ATP levels. Significantly, AD-3 probe was found capable of imaging of HS and ATP in APP/PS1 mice, and the concentration of HS and ATP in the AD mouse brain was found to be lower than that in wild-type mice.