L-Cysteine Provides Neuroprotection of Hypoxia-Ischemia Injury in Neonatal Mice via a PI3K/Akt-Dependent Mechanism

Abstract

Background

Previous work within our laboratory has revealed that hydrogen sulfide (H₂S) can serve as neuroprotectant against brain damage caused by hypoxia-ischemia (HI) exposure in neonatal mice. After HI insult, activation of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has been shown to be implicated in neuro-restoration processes. The goal of the current study was to determine whether the neuroprotective effects of H₂S were mediated by the PI3K/Akt signaling pathway.

Methods

The mouse HI model was built at postnatal day 7 (P7), and the effects of L-Cysteine treatment on acute brain damage (72 h post-HI) and long-term neurological responses (28 days post-HI) were evaluated. Nissl staining and Transmission electron microscopy were used to evaluate the neuronal loss and apoptosis. Immunofluorescence imaging and dihydroethidium staining were utilized to determine glial cell activation and ROS content, respectively.

Results

Quantitative results revealed that L-Cysteine treatment significantly prevented the acute effects of HI on apoptosis, glial cell activation and oxidative injury as well as the long-term effects upon memory impairment in neonatal mice. This protective effect of L-Cysteine was found to be associated with the phosphorylation of Akt and phosphatase and a tensin homolog deletion on chromosome 10 (PTEN). Following treatment with the PI3K inhibitor, LY294002, the neuroprotective effects of L-Cysteine were attenuated.

Conclusion

PTEN/PI3K/Akt signaling was involved in mediating the neuroprotective effects of exogenous H₂S against HI exposure in neonatal mice.

Keywords:

• Akt
• H₂S
• hypoxia-ischemia
• neuroinflammation

Acknowledgments

Research funding support for this work was from the National Natural Science Foundation of China (No. 82072535, 81873768 and 81671213) to Dr. Zhen Wang, the National Key Research and Development Program of China (No. 2017YFC0820203) to Dr. Dexiang Liu and the National Natural Science Foundation of China (81873865) to Dr. Shuanglian Wang.

Abbreviations

Akt, protein kinase B; CNS, central nervous system; DAPI, 4′,6′-diamidino-2-phenylindole dihydrochloride hydrate; DHE, 2-hydroethidium; HI, hypoxia-ischemic; Iba-1, ionized calcium binding adapter molecule 1; PBS, phosphate-buffered saline; PI3K, phosphoinositide 3-kinase; PTEN, phosphatase and tensin homolog deleted on chromosome 10; P-PTEN, phosphorylated PTEN; ROS, reactive oxygen species; TTC, 2,3,5-triphenyltetrazolium chloride monohydrate.

Author Contributions

All authors made a significant contribution to the work, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

There are no competing financial interests. The authors report no conflicts of interest in this work.