Imaging of the mutual regulation between zinc cation and nitrosyl via two-photon fluorescent probes in cells and in vivo

The homeostatic disorder of intracellular Zn2+ pool is closely associated with severe diseases. It has been reported that the high level of free Zn2+ during ischemia/reperfusion (I/R) process can result in oxidative stress damage on nerve cells. Given that nitrosyl (HNO) can aggravate the nerve injury during cerebral I/R process, we assume that there may exist a mutual regulation between Zn2+ and HNO under certain physiological conditions. To reveal this potential small-signaling-molecule crosstalk, we synthesized two-photon fluorescent probes CHP-H and CHP-CH3 to monitor intracellular Zn2+ in cell and mice hippocampus I/R models. The probes consist of two moieties: coumarin derivative as the two-photon fluorescence transducer, 2-hydrazino pyridine as the fluorescence modulator and Zn2+ chelator. Both probes exhibit excellent analytical properties for Zn2+ detection in simulated physiological systems. Utilizing CHP-H and an HNO probe Cyto-JN, we perform fluorescent imaging of cell I/R models. The results confirm that HNO can stimulate Zn2+ release from labile Zn2+ pool, whereas, the increase of intracellular Zn2+ cannot upregulate the level of HNO. Combining with the deep tissue imaging of mice hippocampus tissues, our probes may provide potential approaches for the medical diagnostic assessment of HNO regulation effect on Zn2+ release in clinical cerebral I/R-related diseases.