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Am J Physiol Regul Integr Comp Physiol ; 311(6): R1173-R1185, 2016 12 01.
Article in English | MEDLINE | ID: mdl-27681328

ABSTRACT

Shiga toxin 2 (Stx2)-producing enterohemorrhagic induced brain damage. Since a cerebroprotective action was reported for angiotensin (Ang)-(1-7), our aim was to investigate whether Ang-(1-7) protects from brain damage induced by Stx2-producing enterohemorrhagic Escherichia coli The anterior hypothalamic area of adult male Wistar rats was injected with saline solution or Stx2 or Stx2 plus Ang-(1-7) or Stx2 plus Ang-(1-7) plus A779. Rats received a single injection of Stx2 at the beginning of the experiment, and Ang-(1-7), A779, or saline was administered daily in a single injection for 8 days. Cellular ultrastructural changes were analyzed by transmission electron microscopy. Stx2 induced neurodegeneration, axonal demyelination, alterations in synapse, and oligodendrocyte and astrocyte damage, accompanied by edema. Ang-(1-7) prevented neuronal damage triggered by the toxin in 55.6 ± 9.5% of the neurons and the Stx2-induced synapse dysfunction was reversed. In addition, Ang-(1-7) blocked Stx2-induced demyelination in 92 ± 4% of the axons. Oligodendrocyte damage caused by Stx2 was prevented by Ang-(1-7) but astrocytes were only partially protected by the peptide (38 ± 5% of astrocytes were preserved). Ang-(1-7) treatment resulted in 50% reduction in the number of activated microglial cells induced by Stx2, suggesting an anti-inflammatory action. All these beneficial effects elicited by Ang-(1-7) were blocked by the Mas receptor antagonist and thus it was concluded that Ang-(1-7) protects mainly neurons and oligodendrocytes, and partially astrocytes, in the central nervous system through Mas receptor stimulation.


Subject(s)
Angiotensin I/administration & dosage , Escherichia coli Infections/prevention & control , Hypothalamus/pathology , Infectious Encephalitis/chemically induced , Infectious Encephalitis/prevention & control , Peptide Fragments/administration & dosage , Shiga Toxin 2/toxicity , Animals , Escherichia coli Infections/chemically induced , Escherichia coli Infections/pathology , Hypothalamus/drug effects , Infectious Encephalitis/pathology , Male , Neuroprotective Agents/administration & dosage , Rats , Rats, Wistar , Shiga-Toxigenic Escherichia coli/metabolism , Treatment Outcome
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