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Magnesium induces preconditioning of the neonatal brain via profound mitochondrial protection.

ABSTRACT: Magnesium sulphate (MgSO4) given to women in preterm labor reduces cerebral palsy in their offspring but the mechanism behind this protection is unclear, limiting its effective, safe clinical implementation. Previous studies suggest that MgSO4 is not neuroprotective if administered during or after the insult, so we hypothesised that MgSO4 induces preconditioning in the immature brain. Therefore, we administered MgSO4 at various time-points before/after unilateral hypoxia-ischemia (HI) in seven-day-old rats. We found that MgSO4 treatment administered as a bolus between 6 days and 12?h prior to HI markedly reduced the brain injury, with maximal protection achieved by 1.1?mg/g MgSO4 administered 24?h before HI. As serum magnesium levels returned to baseline before the induction of HI, we ascribed this reduction in brain injury to preconditioning. Cerebral blood flow was unaffected, but mRNAs/miRNAs involved in mitochondrial function and metabolism were modulated by MgSO4. Metabolomic analysis (H+-NMR) disclosed that MgSO4 attenuated HI-induced increases in succinate and prevented depletion of high-energy phosphates. MgSO4 pretreatment preserved mitochondrial respiration, reducing ROS production and inflammation after HI. Therefore, we propose that MgSO4 evokes preconditioning via induction of mitochondrial resistance and attenuation of inflammation.

SUBMITTER: Koning G

PROVIDER: S-EPMC6547197 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Magnesium induces preconditioning of the neonatal brain via profound mitochondrial protection.

Koning Gabriella G Leverin Anna-Lena AL Nair Syam S Schwendimann Leslie L Ek Joakim J Carlsson Ylva Y Gressens Pierre P Thornton Claire C Wang Xiaoyang X Mallard Carina C Hagberg Henrik H

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 20171205 6

Magnesium sulphate (MgSO4) given to women in preterm labor reduces cerebral palsy in their offspring but the mechanism behind this protection is unclear, limiting its effective, safe clinical implementation. Previous studies suggest that MgSO4 is not neuroprotective if administered during or after the insult, so we hypothesised that MgSO4 induces preconditioning in the immature brain. Therefore, we administered MgSO4 at various time-points before/after ...[more]

PMID: 29206066

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Project description:Repetitive hypoxic preconditioning (RHP) creates an anti-inflammatory phenotype that protects from stroke-induced injury for months after a 2-week treatment. The mechanisms underlying long-term tolerance are unknown, though one exposure to hypoxia significantly increased peripheral B cell representation. For this study, we sought to determine if RHP specifically recruited B cells into the protected ischemic hemisphere, and whether RHP could phenotypically alter B cells prior to stroke onset.Adult, male SW/ND4 mice received RHP (nine exposures over 2 weeks; 8 to 11 % O2; 2 to 4 hours) or identical exposures to 21 % O2 as control. Two weeks following RHP, a 60-minute transient middle cerebral artery occlusion was induced. Standard techniques quantified CXCL13 mRNA and protein expression. Two days after stroke, leukocytes were isolated from brain tissue (70:30 discontinuous Percoll gradient) and profiled on a BD-FACS Aria flow cytometer. In a separate cohort without stroke, sorted splenic CD19+ B cells were isolated 2 weeks after RHP and analyzed on an Illumina MouseWG-6 V2 Bead Chip. Final gene pathways were determined using Ingenuity Pathway Analysis. Student's t-test or one-way analysis of variance determined significance (P?<?0.05).CXCL13, a B cell-specific chemokine, was upregulated in post-stroke cortical vessels of both groups. In the ischemic hemisphere, RHP increased B cell representation by attenuating the diapedesis of monocyte, macrophage, neutrophil and T cells, to quantities indistinguishable from the uninjured, contralateral hemisphere. Pre-stroke splenic B cells isolated from RHP-treated mice had >1,900 genes differentially expressed by microarray analysis. Genes related to B-T cell interactions, including antigen presentation, B cell differentiation and antibody production, were profoundly downregulated. Maturation and activation were arrested in a cohort of B cells from pre-stroke RHP-treated mice while regulatory B cells, a subset implicated in neurovascular protection from stroke, were upregulated.Collectively, our data characterize an endogenous neuroprotective phenotype that utilizes adaptive immune mechanisms pre-stroke to protect the brain from injury post-stroke. Future studies to validate the role of B cells in minimizing injury and promoting central nervous system recovery, and to determine whether B cells mediate an adaptive immunity to systemic hypoxia that protects from subsequent stroke, are needed.

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Magnesium induces preconditioning of the neonatal brain via profound mitochondrial protection.

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Magnesium induces preconditioning of the neonatal brain via profound mitochondrial protection.

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