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- Chavez-Valdez, R., et al.
(author)
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Evidence for Sexual Dimorphism in the Response to TLR3 Activation in the Developing Neonatal Mouse Brain: A Pilot Study
- 2019
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In: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 10
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Journal article (peer-reviewed)abstract
- Toll-like receptor (TLR)3 activation during the neonatal period produces responses linked to the origins of neuropsychiatric disorders. Although there is sexual dimorphism in neuropsychiatric disorders, it is unknown if brain responses to TLR3 activation are sex-specific. We hypothesized that poly I:C in a post-natal day (P)8 model induces a sexually dimorphic inflammatory responses. C57BL6 mice received intraperitoneal injection of poly I:C (10 mg/kg) or vehicle [normal saline (NS)] at P8. Pups were killed at 6 or 14 h for caspase 3 and 8 activity assays, NFkB ELISA, IRF3, AP1, and GFAP western blotting and cytokines/chemokines gene expression real time qRT-PCR (4-6/group). A second group of pups were killed at 24 h (P9) or 7 days (P15) after poly I:C to assess astrocytic (GFAP) and microglia (Iba1) activation in the hippocampus, thalamus and cortex using immunohistochemistry, and gene and protein expression of cytokines/chemokines using real time RT-PCR and MSD, respectively (4-6/group). Nonparametric analysis was applied. Six hours after poly I:C, caspase-3 and -8 activities in cytosolic fractions were 1.6 and 2.8-fold higher in poly I:C-treated than in NS-treated female mice, respectively, while gene expressions of pro-inflammatory cytokines were upregulated in both sexes. After poly I:C, IRF3 nuclear translocation occurred earlier (6 h) in female mice and later (14 h) in male mice. At 14 h after poly I:C, only male mice also had increased nuclear NF kappa B levels (88%, p < 0.001) and GFAP expression coinciding with persistent IL-6 and FAS gene upregulation (110 and 77%, respectively; p < 0.001) and IL-10 gene downregulation (-42%, p < 0.05). At 24 h after poly I:C, IL-1 beta, CXCL-10, TNF-alpha, and MCP-1 were similarly increased in both sexes but at 7 days after exposure, CXCL-10 and INF gamma were increased and IL-10 was decreased only in female mice. Accordingly, microglial activation persisted at 7 days after poly I:C in the hippocampus, thalamus and cortex of female mice. This preliminary study suggests that TLR3 activation may produce in the developing neonatal mouse brain a sexually dimorphic response with early activation of caspase-dependent pathways in female mice, activation of inflammatory cascades in both sexes, which then persists in female mice. Further well-powered studies are essential to confirm these sex-specific findings.
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| 2. |
- Hagberg, Henrik, 1955, et al.
(author)
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PARP-1 gene disruption in mice preferentially protects males from perinatal brain injury
- 2004
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In: J Neurochem. ; 90:5, s. 1068-75
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Journal article (peer-reviewed)abstract
- Poly(ADP-ribose) polymerase-1 is over-activated in the adult brain in response to ischemia and contributes to neuronal death, but its role in perinatal brain injury remains uncertain. To address this issue, 7-day-old wild-type (wt) and PARP-1 gene deficient (parp+/- and parp-/-) Sv129/CD-1 hybrid mice were subjected to unilateral hypoxia-ischemia and histologic damage was assessed 10 days later by two evaluators. Poly(ADP-ribose) polymerase-1 knockout produced moderate but significant (p < 0.05) protection in the total group of animals, but analysis by sex revealed that males were strongly protected (p < 0.05) in contrast to females in which there was no significant effect. Separate experiments demonstrated that PARP-1 was activated over 1-24 h in both females and males after the insult in neonatal wt mice and rats using immnocytochemistry and western blotting for poly(ADP-ribose). Brain levels of NAD+ were also significantly reduced, but the decrease of NAD+ during the early post-hypoxia-ischemia (HI) phase was only seen in males. The results indicate that hypoxia-ischemia activates Poly(ADP-ribose) polymerase-1 in the neonatal brain and that the sex of the animal strongly influences its role in the pathogenesis of brain injury.
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| 3. |
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| 4. |
- Northington, F. J., et al.
(author)
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Failure to complete apoptosis following neonatal hypoxia-ischemia manifests as "continuum" phenotype of cell death and occurs with multiple manifestations of mitochondrial dysfunction in rodent forebrain
- 2007
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In: Neuroscience. - : Elsevier BV. - 0306-4522. ; 149:4, s. 822-33
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Journal article (peer-reviewed)abstract
- Controversy surrounds proper classification of neurodegeneration occurring acutely following neonatal hypoxia-ischemia (HI). By ultrastructural classification, in the first 24 h after neonatal hypoxia-ischemia in the 7-day-old (p7) rat, the majority of striatal cells die having both apoptotic and necrotic features. There is formation of a functional apoptosome, and activation of caspases-9 and -3 occurring simultaneously with loss of structurally intact mitochondria to 34.7+/-25% and loss of mitochondrial cytochrome c oxidase activity to 34.7+/-12.7% of control levels by 3 h after hypoxia-ischemia. There is also loss of the mitochondrial motor protein, kinesin. This combination of activation of apoptosis pathways simultaneous with significant mitochondrial dysfunction may cause incomplete packaging of nuclear and cytoplasmic contents and a hybrid of necrotic and apoptotic features. Evidence for an intermediate biochemistry of cell death including expression of the 17 kDa isoform of caspase-3 in dying neurons lacking a classic apoptotic morphology and degradation of the neuronal cytoskeletal protein spectrin by caspase-3 and calcium-activated calpains yielding 120 kDa and 145/150 kDa fragments, respectively, is also found. In summary, neonatal hypoxia-ischemia triggers apoptotic cascades, and simultaneously causes mitochondrial structural and functional failure. The presence of a "continuum" phenotype of cell death that varies on a cell-by-cell basis suggests that the phenotype of cell death is dependent on the energy available to drive the apoptotic pathways to completion.
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| 5. |
- Payton, K. S., et al.
(author)
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Antioxidant status alters levels of Fas-associated death domain-like IL-1B-converting enzyme inhibitory protein following neonatal hypoxia-ischemia
- 2007
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In: Dev Neurosci. - 1421-9859. ; 29:4-5, s. 403-11
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Journal article (peer-reviewed)abstract
- Activation of Fas death receptor (Fas DR) signaling cascade is seen after neonatal hypoxia-ischemia (HI). Cell survival is favored when signaling through the death-inducing signaling complex and cleavage of caspase 8 to its active form is blocked by FLIP, a dominant negative of caspase 8. H2O2 quickly downregulates expression of FLIP. Neonatal mice overexpressing glutathione peroxidase (GPx) have less injury and less H2O2 accumulation compared with neonatal mice overexpressing superoxide dismutase (SOD) or wild-type (WT) littermates. Expression of both FLIP(L) and FLIP(S) is increased in GPx-oxerexpressing mice relative to WT mice at 24 h and relative to SOD-overexpressing mice at 2 and 24 h following neonatal HI (ANOVA, p < 0.05). There is an increase in Fas DR expression at 24 h in both WT and GPx-overexpressing mice and significant differences between WT and SOD-overexpressing mice (ANOVA, p < 0.01). There is no difference in FADD expression among the 3 groups 24 h after HI. At 24 h following HI, the ratio of FLIP to Fas DR expression supports a significant negative correlation with injury score (r2 = 0.99, slope = -4.01), and expression of both the active fragment of caspase 8 and caspase 8 activity is increased in SOD overexpressors compared to GPx overexpressors at 24 h after HI (ANOVA, p < 0.05). The overall degree of injury previously seen in these 3 strains correlates well with changes in expression of Fas DR signaling proteins favoring neuroprotection in the GPx-overexpressing mice, i.e. increased FLIP expression and decreased caspase 8 activity compared to SODtg mice. The mechanism by which antioxidant status alters FLIP levels following neonatal HI may be related to the ability to detoxify H2O2 produced following neonatal HI.
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| 6. |
- Stridh, Linnea, 1983, et al.
(author)
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Toll-Like Receptor-3 Activation Increases the Vulnerability of the Neonatal Brain to Hypoxia-Ischemia
- 2013
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In: Journal of Neuroscience. - : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 33:29, s. 12041-12051
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Journal article (peer-reviewed)abstract
- Susceptibility and progression of brain injury in the newborn is closely associated with an exacerbated innate immune response, but the underlying mechanisms are often unclear. Toll-like receptors (TLRs) are important innate immune sensors that may influence the vulnerability of the developing brain. In the current study, we provide novel data to show that activation of the viral innate immune receptor TLR-3 sensitizes the neonatal brain to subsequent hypoxic-ischemic (HI) damage. Poly inosinic: poly cytidylic acid (Poly I: C), a synthetic ligand for TLR-3, was administered to neonatal mice 14 h before cerebral HI. Activation of TLR-3 before HI increased infarct volume from 3.0 +/- 0.5 to 15.4 +/- 2.1 mm(3) and augmented loss of myelin basic protein from 13.4 +/- 6.0 to 70.6 +/- 5.3%. The sensitizing effect of Poly I: C was specific for the TLR-3 pathway because mice deficient in the TLR-3 adaptor protein Toll/IL-1R domain-containing adaptor molecule-1 (TRIF) did not develop larger brain damage. The increased vulnerability was associated with a TRIF-dependent heightened inflammatory response, including proinflammatory cytokines, chemokines, and the apoptosis-associated mediator Fas, whereas there was a decrease in reparative M2-like CD11b(+) microglia and phosphorylation of Akt. Because TLR-3 is activated via double-stranded RNA during most viral infections, the present study provides evidence that viral infections during pregnancy or in the neonate could have great impact on subsequent HI brain injury.
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