COMPARATIVE LOCALIZATION OF NITRIC OXIDE SYNTHASE AND TYROSINE HYDROXYLASE IN THE BRAIN OF DIFFERENT VERTEBRATES

Sepsis-associated encephalopathy is an early manifestation of sepsis, resulting in a diffuse dysfunction of the brain. Recently, nitric oxide (NO) has been proposed to be one of the key molecules involved in the modulation of inflammatory responses in the brain. The aim of this study was to assess the role of NO in cerebrovascular endothelial cell activation/dysfunction during the early onsets of sepsis. To this end, we employed an in vitro model of sepsis in which cultured mouse cerebrovascular endothelial cells (MCVEC) were challenged with blood plasma (20% vol/vol) obtained from sham or septic (feces-induced peritonitis, FIP; 6 h) mice. Exposing MCVEC to FIP plasma for 1 h resulted in increased production of reactive oxygen species and NO as assessed by intracellular oxidation of oxidant-sensitive fluorochrome, dihydrorhodamine 123 (DHR 123), and nitrosation of NO-specific probe, DAF-FM, respectively. The latter events were accompanied by dissociation of tight junction protein, occludin, from MCVEC cytoskeletal framework and a subsequent increase in FITC-dextran (3-kDa mol mass) flux across MCVEC grown on the permeable cell culture supports, whereas Evans blue-BSA (65-kDa mol mass) or FITC-dextran (10-kDa mol mass) flux were not affected. FIP plasma-induced oxidant stress, occludin rearrangement, and MCVEC permeability were effectively attenuated by antioxidant, 1-pyrrolidinecarbodithioic acid (PDTC; 0.5 mM), or interfering with nitric oxide synthase (NOS) activity [0.1 mM nitro-l-arginine methyl ester (l-NAME) or endothelial NOS (eNOS)-deficient MCVEC]. However, treatment of MCVEC with PDTC failed to interfere with NO production, suggesting that septic plasma-induced oxidant stress in MCVEC is primarily a NO-dependent event. Taken together, these data indicate that during early sepsis, eNOS-derived NO exhibits proinflammatory characteristics and contributes to the activation and dysfunction of cerebrovascular endothelial cells.

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Isoflurane Preconditioning Induces Neuroprotection That Is Inducible Nitric Oxide Synthase–dependent in Neonatal Rats

Anesthesiology ◽

10.1097/00000542-200409000-00018 ◽

2004 ◽

Vol 101 (3) ◽

pp. 695-703 ◽

Cited By ~ 106

Author(s):

Ping Zhao ◽

Zhiyi Zuo

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Inducible Nitric Oxide Synthase ◽

Weight Ratio ◽

Cerebral Hemispheres ◽

Brain Hypoxia ◽

Hypoxia Ischemia ◽

Oxide Synthase ◽

The Brain ◽

Inducible Nitric Oxide

Background Perinatal stroke is a common human disease. Neonatal brains are immature and engaged in active synaptogenesis. Preconditioning adult rats with the volatile anesthetic isoflurane induces neuroprotection. Whether isoflurane preconditioning induces neuroprotection in neonates is not known. Methods Seven-day-old Sprague-Dawley rats had left common carotid arterial ligation followed by hypoxia with 8% oxygen for 1, 2, or 2.5 h at 37 degrees C. Isoflurane preconditioning with 1 or 1.5% isoflurane for 30 min was performed at 24 h before the brain hypoxia/ischemia. The inducible nitric oxide synthase inhibitor aminoguanidine (200 mg/kg, intraperitoneally) was administered 30 min before the isoflurane pretreatment. The weight ratio of left to right cerebral hemispheres at 7 days after the brain hypoxia/ischemia was calculated. The mortality during the period from cerebral hypoxia/ischemia to 7 days afterwards was monitored. In another experiment, 6-day-old rats were exposed to 1.5% isoflurane for 30 min. The cerebral hemispheres were removed at various time points for Western analysis of inducible nitric oxide synthase. Results The mortality was about 40% in neonates with brain hypoxia/ischemia for 2 h or 2.5 h and was not altered by isoflurane preconditioning. The weight ratio of left/right cerebral hemispheres in the survivors was 0.99 +/- 0.02, 0.65 +/- 0.19, and 0.86 +/- 0.15 (n = 7-18) for the rats in control, brain hypoxia/ischemia for 2.5 h, and isoflurane preconditioning plus brain hypoxia/ischemia for 2.5 h groups, respectively (P < 0.05 for the comparisons between control versus brain hypoxia/ischemia and brain hypoxia/ischemia versus isoflurane preconditioning plus brain hypoxia/ischemia). This isoflurane preconditioning-induced neuroprotection was abolished by aminoguanidine (the weight ratio was 0.61 +/- 0.18, n = 12). Isoflurane induced a time-dependent increase in the inducible nitric oxide synthase proteins. Conclusions Isoflurane preconditioning induces neuroprotection in neonatal rats. This neuroprotection is inducible nitric oxide synthase-dependent.

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