Hydrogen Sulfide, the third gas transmitter, has been proven to be neuroprotective in cerebral ischemia injury, but whether its effect is mediated by regulating autophagy is not yet clear. The present study was undertaken to explore the underlying mechanisms of exogenous H 2 S on autophagy regulation in cerebral ischemia. The effects and its connection with autophagy of NaHS, a H 2 S donor, were observed through neurological deficits and cerebral infarct volume in middle cerebral artery occlusion (MCAO) mice; autophagy related proteins and autophagy complex levels in ischemia hemisphere were detected with western blot assay. Compared to model group, NaHS significantly decreased infarct volume and improved neurological deficits; Rapamycin, an autophagy activator, abolished the effect of NaHS; NaHS decreased the expression of LC3-II and up-regulated p62 expression in ischemia cortex 24 hours after ischemia. However, NaHS did not significantly influence Beclin-1 expression. H 2 S has neuroprotective effect on ischemia injury in MCAO mice, this effect is associated with its influence in down-regulating autophagosomes accumulation.

Hydrogen sulfide (HS), an endogenous gaseous signal molecule, exhibits protective effect against ischemic injury. However, its underlying mechanism is not fully understood. We have recently reported that exogenous HS decreases the accumulation of autophagic vacuoles in mouse brain with ischemia/reperfusion (I/R) injury. To further investigate whether this HS-induced reduction of autophagic vacuoles is caused by the decreased autophagosome synthesis and/or the increased autophagic degradation inautophagic flux, we performed in vitro and in vivo studies using SH-SY5Y cells for the oxygen and glucose deprivation/reoxygenation (OGD/R) and mice for the cerebral I/R, respectively. NaHS (a donor of HS) treatment significantly increased cell viability and reduced cerebral infarct volume. NaHS treatment reduced the OGD/R-induced elevation in LC3-II (an autophagic marker), which was completely reversed by co-treatment with an autophagic flux inhibitor bafilomycin A (BafA1). However, HS did not affect the OGD/R-induced increase of the ULK1 self-association and decrease of the ATG13 phosphorylation, which are the critical steps for the initiation of autophagosome formation. Cerebral I/R injury caused an increase in LC3-II, a decrease in p62 and the accumulation of autophagosomes in the cortex and the hippocampus, which were inhibited by NaHS treatment. This HS-induced decline of LC3-II in ischemic brain was reversed by BafA1. Moreover, BafA1 treatment abolished the protection of HS on the cerebral infarction. Collectively, the neuroprotection of exogenous HS against ischemia/hypoxia and reperfusion/reoxygenation injury is mediated by the enhancement of autophagic degradation.

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Phthalazinone derivatives were designed as optical probes for one- and two-photon fluorescence microscopy imaging. The design strategy involves stepwise extension and modification of pyridazinone by 1) expansion of pyridazinone to phthalazinone, a larger conjugated system, as the electron acceptor, 2) coupling of electron-donating aromatic groups such as N,N-diethylaminophenyl, thienyl, naphthyl, and quinolyl to the phthalazinone, and 3) anchoring of an alkyl chain to the phthalazinone with various terminal substituents such as triphenylphosphonio, morpholino, triethylammonio, N-methylimidazolio, pyrrolidino, and piperidino. Theoretical calculations were utilized to verify the initial design. The desired fluorescent probes were synthesized by two different routes in considerable yields. Twenty-two phthalazinone derivatives were synthesized and their photophysical properties were measured. Selected compounds were applied in cell imaging, and valuable information was obtained. Furthermore, the designed compounds showed excellent performance in two-photon microscopic imaging of mouse brain slices.

A class of pyridazinone derivatives as near‐infrared optical probes in fluorescence microscopy images was designed. The design strategy consisted of the stepwise extension and modification of pyridazinone by expansion of the electron‐donating moiety to a larger π‐conjugated system and anchoring a subcellular directing group such as triphenylphosphine or morpholine. All the desired products were successfully applied in cell imaging with high subcellular colocalization. Furthermore, these fluorescent probes showed excellent performance in mouse‐brain imaging.