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Effects of Induction of Inducible Nitric Oxide Synthase on Brain Cortical Blood Flow and Blood-Brain Barrier

  • N. Suzuki
  • Y. Fukuuchi
  • A. Koto
  • Y. Morita
  • T. Shimizu
  • M. Takao
  • M. Aoyama
Part of the Advances in Behavioral Biology book series (ABBI, volume 46)

Summary

Recently, nitric oxide (NO) has been found to act a crucial role in the development of the endotoxin shock. This study aims to observe vascular changes and to elucidate mechanisms of development of the brain damage in the endotoxin shock.

Five male Sprague-Dawley rats, weighing 250–300g, were anesthetized with α-chloralose and urethane, and ventilated with room air. The brain cortical blood flow (CoBF) in the parietal cortex supplied by the right middle cerebral artery was recorded by a laser-Doppler flowmeter. CoBF and systemic blood pressure were continuously recorded before and after an intraperitoneal injection of E.coli lipopolysaccharide (4mg/kg b.wt.). Three hours after the injection of LPS, the horseradish peroxidase was injected intravenously. One hour later, the animals were deeply anesthetized and perfused with 5% glutaraldehyde. The whole brain was dissected and frozen sections of the deep frontal cortex were incubated for horseradish peroxidase (HRP) activity, using a method of Graham and Karnovsky. They were post fixed in osmic acid, then processed and observed with an electron microscope. An electron microscopic NADPH-diaphorase histochemistry was also performed in these sections. The blood pressure was significantly decreased ca.30 min after LPS administration and a sustained increase (ca.30%) in CoBF was observed.

The deposits of HRP were observed as dark clusters at the outer adjacency of the endothelial cells. NADPH-d positive deposits were observed in the nuclear membranes, endoplasmic reticula and mitochondria in the smooth muscle as well as in the endothelia.

The NOS induced in the endotoxin shock may affect the function of the endothelium and the smooth muscle, which constitute BBB, and act as a crucial mediator in developing the septic encephalopathy.

Keywords

Nitric Oxide Nitric Oxide Positive Material Endotoxin Shock Osmic Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Résumé

Il a été établi récemment que l’oxyde nitrique NO jouait un rôle crucial dans le développement des chocs septiques dus aux endotoxines. Cette étude a pour but d’étudier les modifications vasculaires et d’élucider les mécanismes qui provoquent des lésions du cerveau par suite de ce phénomène.

Cinq rats males Sprague-Dawley, pesant de 250 à 300 g, ont été anesthésiés par l’α—chloralose et l’uréthane, sous ventilation à l’air ambient. La circulation corticale du cerveau (CoBF) dans le cortex pariétal, assurée par l’artère cérébrale centrale droite, a été enregistrée au moyen d’un fluxmètre laser-Doppler. La CoBF et la pression systémique artérielle ont été enregistrées en continu avant et après une injection intrapéritonéale de liposaccharide de E. coli, à raison de 4 mg/kg de poids corporel. Trois heures après l’injection de LPS, la peroxydase de raifort était injectée par voie intraveineuse. Une heure plus tard, les animaux ont été anesthésiés plus profondément et perfusés avec du glutaraldéhyde à 5%. Le cerveau entier a été disséqué, et des coupes congelées du cortex frontal profond ont été incubées pour révéler l’activité de la peroxydase de raifort (HRP), selon la méthode de Graham et Karnovsky. Les coupes ont été ensuite fixées à l’acide osmique et étudiées par microscopie électronique. Une étude histochimique par microscopie électronique avec la NADPH-diaphorase a été également réalisée sur ces coupes.

La pression artérielle diminue significativement environ 30 mn après l’administration de LPS, et on observe une CoBF accrue (environ 30%) et persistante.

Les dépôts de HRP apparaissent comme des amas noirs sur le pourtour des cellules endothéliales. Les dépôts positifs de NADPH-d apparaissent sur les membranes nucléaires, le réticulum endoplasmique, et les mitochondries, dans le muscle lisse comme dans l’endothélium.

On en déduit que le NO induit dans les chocs septiques dus aux endotoxines doit affecter la fonction de l’endothélium et du muscle lisse, qui constituent la BHE, et agir comme un médiateur crucial du développement de l’encéphalopathie septique.

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Copyright information

© Springer Science+Business Media New York 1996

Authors and Affiliations

  • N. Suzuki
    • 1
  • Y. Fukuuchi
    • 1
  • A. Koto
    • 1
  • Y. Morita
    • 1
  • T. Shimizu
    • 1
  • M. Takao
    • 1
  • M. Aoyama
    • 1
  1. 1.Department of NeurologyKeio UniversityTokyoJapan

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