Abstract
BackgroundHypoxia-ischemia (HI) during the perinatal period is one of the most common causes of acute mortality and chronic neurologic morbidity. Hydrogen-rich saline (HS) treatment in neonatal mice has been reported to alleviate brain injury following HI, but the mechanisms involved are not known.MethodsA modified version of the Rice-Vannucci method for the induction of neonatal HI brain injury was performed on postnatal day 7 mouse pups. Animals or BV2-cells received HS and an AMPK inhibitor at indicative time post-injury.ResultsIn the current study, we show that HS treatment attenuated the accumulation of CD11b+/CD45high cells, suppressed HI-induced neuro-inflammation, induced microglial anti-inflammatory M2 polarization, was associated with promoting AMPK activation, and inhibited nuclear factor-κB activation as demonstrated both in vivo and in vitro. In addition, HS treatment reversed HI-induced neurological disabilities, was associated with improving damaged synapses, and restored the expression levels of synaptophysin and postsynaptic density protein 95 following HI insult. Furthermore, HI insult which increased levels of complement component C1q, C3, and C3aR1 was observed. Importantly, C1q deposited in the infarct core and lesion boundary zone following HI injury, was found to co-localize within regions of synapse loss, whereas HS treatment reversed these effects of HI on synapse loss and complement component levels. Notably, the AMPK inhibitor reversed the beneficial effects of HS as described above.ConclusionsThese results demonstrate that HS restored behavioral deficits after HI in neonatal mice. These beneficial effects, in part, involve promoting microglia M2 polarization and complement-mediated synapse loss via AMPK activation.
Highlights
Neonatal hypoxic-ischemic encephalopathy (HIE) is one of the most common causes of morbidity and mortality in infants
Hydrogen-rich saline (HS) promoted AMP-activated protein kinase (AMPK) phosphorylation in vivo and in vitro In the absence of LPS, HS (1 μM) produced an overall increase in p-AMPK levels within BV-2 cells (p < 0.001, Fig. 1a). These effects appeared to be temporally dependent with increases observed at both 2 (p < 0.001) and 4 (p < 0.001) h after HS treatment in these BV-2 cells (Fig. 1b)
HS treatment further upregulated p-AMPK expression (Fig. 1e, p < 0.01), while Compound C blocked this effect of HS on AMPK activation in the lesioned cortex (Fig. 1e, p < 0.05)
Summary
Neonatal hypoxic-ischemic encephalopathy (HIE) is one of the most common causes of morbidity and mortality in infants. Following HI an immediate activation of microglia occurs, which is involved with mediating the brain injury observed [2, 3]. M1-activated microglia express CD16 and CD86 and release inflammatory cytokines, including tumor necrosis factor (TNF)-a and interleukin (IL)-1β, which enhance brain damage. M2 -activated microglia express CD206 and YM-1 and release anti-inflammatory cytokines and growth factors, including IL-10 and transforming growth factor β (TGF-β), which leads to neuroprotection. Findings from a number of studies have indicated that mediating microglial phenotype shifts associated with CNS damage, including HI in neonatal animals can exert beneficial effects with regard to neurological recovery [4, 5]. Hydrogen-rich saline (HS) treatment in neonatal mice has been reported to alleviate brain injury following HI, but the mechanisms involved are not known
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
