The akt-endothelial nitric oxide synthase pathway in lipopolysaccharide preconditioning-induced hypoxic-ischemic tolerance in the neonatal rat brain

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Abstract

Background and purpose: Low-dose lipopolysaccharide (LPS) preconditioning provides neonatal rats long-term neuroprotection against hypoxic ischemia (HI). Upregulating endothelial nitric oxide synthase (eNOS) protects against cerebral ischemia; however, whether eNOS is required for LPS preconditioning-induced protection in neonatal rats is unknown. We hypothesized that Akt activation, which upregulates eNOS in neurons and endothelial cells, is required for LPS preconditioning-induced tolerance against HI in the neonatal brain. Methods: Six-day-old rat pups were intraperitoneally injected with LPS (0.05 mg/kg) or normal saline 24 hours before HI. Immunoblotting and immunohistochemistry were used to determine the phospho-Akt (pAkt Ser473), phospho-eNOS (peNOS Ser1177), and eNOS levels and immunofluorescence to determine the cellular distribution of eNOS and pAkt Ser473. Pharmacological and genetic approaches were used to regulate Akt and eNOS, and the weight loss of cerebral hemispheres on postnatal Day 21 was used to assess outcomes. Results: eNOS, peNOS (Ser1177), and pAkt (Ser473) levels were significantly higher in LPS-than in normal saline-treated rats 24 hours postinjection. LPS-induced eNOS was expressed primarily in neurons and vascular endothelial cells. N-omega(ω)-nitro-l-arginine and antisense oligodeoxynucleotide treatment significantly reduced eNOS expression in neurons and endothelial cells and inhibited LPS-induced protection against HI in rat pups. l-arginine and adenovirus eNOS transfection upregulated eNOS and protected the rat pups against HI. Wortmannin treatment before LPS preconditioning significantly reduced eNOS expression in neurons and endothelial cells, which inhibited LPS-induced protection against HI. Conclusions: Akt-mediated eNOS upregulation in neurons and vascular endothelial cells is required for LPS-induced tolerance against HI in the neonatal rat brain.

Original languageEnglish
Pages (from-to)1543-1551
Number of pages9
JournalStroke
Volume41
Issue number7
DOIs
Publication statusPublished - 2010 Jul 1

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Nitric Oxide Synthase Type III
Lipopolysaccharides
Brain
Ischemia
Endothelial Cells
Neurons
Arginine
Up-Regulation
Oligodeoxyribonucleotides
Cerebrum
Brain Ischemia
Immunoblotting
Adenoviridae
Fluorescent Antibody Technique
Transfection
Weight Loss
Immunohistochemistry

All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine
  • Clinical Neurology
  • Advanced and Specialised Nursing
  • Medicine(all)

Cite this

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title = "The akt-endothelial nitric oxide synthase pathway in lipopolysaccharide preconditioning-induced hypoxic-ischemic tolerance in the neonatal rat brain",
abstract = "Background and purpose: Low-dose lipopolysaccharide (LPS) preconditioning provides neonatal rats long-term neuroprotection against hypoxic ischemia (HI). Upregulating endothelial nitric oxide synthase (eNOS) protects against cerebral ischemia; however, whether eNOS is required for LPS preconditioning-induced protection in neonatal rats is unknown. We hypothesized that Akt activation, which upregulates eNOS in neurons and endothelial cells, is required for LPS preconditioning-induced tolerance against HI in the neonatal brain. Methods: Six-day-old rat pups were intraperitoneally injected with LPS (0.05 mg/kg) or normal saline 24 hours before HI. Immunoblotting and immunohistochemistry were used to determine the phospho-Akt (pAkt Ser473), phospho-eNOS (peNOS Ser1177), and eNOS levels and immunofluorescence to determine the cellular distribution of eNOS and pAkt Ser473. Pharmacological and genetic approaches were used to regulate Akt and eNOS, and the weight loss of cerebral hemispheres on postnatal Day 21 was used to assess outcomes. Results: eNOS, peNOS (Ser1177), and pAkt (Ser473) levels were significantly higher in LPS-than in normal saline-treated rats 24 hours postinjection. LPS-induced eNOS was expressed primarily in neurons and vascular endothelial cells. N-omega(ω)-nitro-l-arginine and antisense oligodeoxynucleotide treatment significantly reduced eNOS expression in neurons and endothelial cells and inhibited LPS-induced protection against HI in rat pups. l-arginine and adenovirus eNOS transfection upregulated eNOS and protected the rat pups against HI. Wortmannin treatment before LPS preconditioning significantly reduced eNOS expression in neurons and endothelial cells, which inhibited LPS-induced protection against HI. Conclusions: Akt-mediated eNOS upregulation in neurons and vascular endothelial cells is required for LPS-induced tolerance against HI in the neonatal rat brain.",
author = "Lin, {Hsiang Yin} and Chao-Liang Wu and Chao-Ching Huang",
year = "2010",
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doi = "10.1161/STROKEAHA.109.574004",
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TY - JOUR

T1 - The akt-endothelial nitric oxide synthase pathway in lipopolysaccharide preconditioning-induced hypoxic-ischemic tolerance in the neonatal rat brain

AU - Lin, Hsiang Yin

AU - Wu, Chao-Liang

AU - Huang, Chao-Ching

PY - 2010/7/1

Y1 - 2010/7/1

N2 - Background and purpose: Low-dose lipopolysaccharide (LPS) preconditioning provides neonatal rats long-term neuroprotection against hypoxic ischemia (HI). Upregulating endothelial nitric oxide synthase (eNOS) protects against cerebral ischemia; however, whether eNOS is required for LPS preconditioning-induced protection in neonatal rats is unknown. We hypothesized that Akt activation, which upregulates eNOS in neurons and endothelial cells, is required for LPS preconditioning-induced tolerance against HI in the neonatal brain. Methods: Six-day-old rat pups were intraperitoneally injected with LPS (0.05 mg/kg) or normal saline 24 hours before HI. Immunoblotting and immunohistochemistry were used to determine the phospho-Akt (pAkt Ser473), phospho-eNOS (peNOS Ser1177), and eNOS levels and immunofluorescence to determine the cellular distribution of eNOS and pAkt Ser473. Pharmacological and genetic approaches were used to regulate Akt and eNOS, and the weight loss of cerebral hemispheres on postnatal Day 21 was used to assess outcomes. Results: eNOS, peNOS (Ser1177), and pAkt (Ser473) levels were significantly higher in LPS-than in normal saline-treated rats 24 hours postinjection. LPS-induced eNOS was expressed primarily in neurons and vascular endothelial cells. N-omega(ω)-nitro-l-arginine and antisense oligodeoxynucleotide treatment significantly reduced eNOS expression in neurons and endothelial cells and inhibited LPS-induced protection against HI in rat pups. l-arginine and adenovirus eNOS transfection upregulated eNOS and protected the rat pups against HI. Wortmannin treatment before LPS preconditioning significantly reduced eNOS expression in neurons and endothelial cells, which inhibited LPS-induced protection against HI. Conclusions: Akt-mediated eNOS upregulation in neurons and vascular endothelial cells is required for LPS-induced tolerance against HI in the neonatal rat brain.

AB - Background and purpose: Low-dose lipopolysaccharide (LPS) preconditioning provides neonatal rats long-term neuroprotection against hypoxic ischemia (HI). Upregulating endothelial nitric oxide synthase (eNOS) protects against cerebral ischemia; however, whether eNOS is required for LPS preconditioning-induced protection in neonatal rats is unknown. We hypothesized that Akt activation, which upregulates eNOS in neurons and endothelial cells, is required for LPS preconditioning-induced tolerance against HI in the neonatal brain. Methods: Six-day-old rat pups were intraperitoneally injected with LPS (0.05 mg/kg) or normal saline 24 hours before HI. Immunoblotting and immunohistochemistry were used to determine the phospho-Akt (pAkt Ser473), phospho-eNOS (peNOS Ser1177), and eNOS levels and immunofluorescence to determine the cellular distribution of eNOS and pAkt Ser473. Pharmacological and genetic approaches were used to regulate Akt and eNOS, and the weight loss of cerebral hemispheres on postnatal Day 21 was used to assess outcomes. Results: eNOS, peNOS (Ser1177), and pAkt (Ser473) levels were significantly higher in LPS-than in normal saline-treated rats 24 hours postinjection. LPS-induced eNOS was expressed primarily in neurons and vascular endothelial cells. N-omega(ω)-nitro-l-arginine and antisense oligodeoxynucleotide treatment significantly reduced eNOS expression in neurons and endothelial cells and inhibited LPS-induced protection against HI in rat pups. l-arginine and adenovirus eNOS transfection upregulated eNOS and protected the rat pups against HI. Wortmannin treatment before LPS preconditioning significantly reduced eNOS expression in neurons and endothelial cells, which inhibited LPS-induced protection against HI. Conclusions: Akt-mediated eNOS upregulation in neurons and vascular endothelial cells is required for LPS-induced tolerance against HI in the neonatal rat brain.

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U2 - 10.1161/STROKEAHA.109.574004

DO - 10.1161/STROKEAHA.109.574004

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VL - 41

SP - 1543

EP - 1551

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JF - Stroke

SN - 0039-2499

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