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Bacterial endotoxin sensitizes the immature brain to hypoxic–ischaemic injury

Authors

  • Saskia Eklind,

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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  • 1 Carina Mallard,

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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  • 2 Anna-Lena Leverin,

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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  • 2 Erik Gilland,

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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  • 2 Klas Blomgren,

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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  • 2 Inger Mattsby-Baltzer,

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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  • and 3 Henrik Hagberg 1

    1. 1 Perinatal Center, Department of Obstetrics and Gynecology, Institute of the Health of Women and Children, Göteborg University, Göteborg, Sweden 2 Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Göteborg, Sweden 3 Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden
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: Dr Carina Mallard, Perinatal Center, Department of Physiology and Pharmacology, Göteborg University, Box 432, 405 30 Göteborg, Sweden.
E-mail: carina.mallard@fysiologi.gu.se

Abstract

Epidemiological studies show a markedly increased risk of cerebral palsy following the combined exposure of infection and birth asphyxia. However, the underlying mechanisms of this increased vulnerability remain unclear. We have examined the effects of a low dose of bacterial endotoxin on hypoxic–ischaemic injury in the immature brain of rats. Bacterial endotoxin (lipopolysaccharide 0.3 mg/kg) was administered to 7-day-old rats 4 h prior to unilateral hypoxia–ischaemia and the neurological outcome was determined 3 days later. Rectal temperature and cerebral blood flow was measured during the study and the expression of CD14 and toll-like receptor-4 mRNA in the brain was examined. We found that a low dose of endotoxin dramatically sensitizes the immature brain to injury and induces cerebral infarction in response to short periods of hypoxia–ischaemia that by themselves caused no or little injury. This effect could not be explained by a reduction in cerebral blood flow or hyperthermia. In association with the sensitization of injury we found an altered expression of CD14 mRNA and toll-like receptor-4 mRNA in the brain. These results suggest that the innate immune system may be involved in the vulnerability of the immature brain following the combination of infection and hypoxia–ischaemia.

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