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Intestinal lesion induced by hypoxia/reoxygenation in newborn rats. Modulation by L-arginine and remote ischemic preconditioning in uterus

Grant number: 07/06754-6
Support Opportunities:Regular Research Grants
Duration: January 01, 2008 - December 31, 2010
Field of knowledge:Health Sciences - Medicine - Surgery
Principal Investigator:Jose Luiz Martins
Grantee:Jose Luiz Martins
Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Considering that premature birth is a clinical occurrence common to patients with necrotizing enterocolitis, and that is sometimes a predictable situation, we decide to verify the hypothesis that L-arginine and/or remote ischemic preconditioning during the intra uterine phase would prevent the intestinal injury induced by neonatal hypoxia and reoxygenation. It will be utilized pregnant rats and their offspring divided in six groups: Group Ref (n=10)-newborn rats from pregnant rat without any intervention; Group HR (n=10) - newborn rats, from pregnant rat without any intervention, that will be submitted to hypoxia/reoxygenation; Group Larg (n=10) - newborn rats, from pregnant rat treated with L-arginine 24hours before delivery, that will be submitted to hypoxia/reoxygenation; Group Larg-pos (n=10) - newborn rats treated with L-arginine before to be submitted to hypoxia/reoxygenation; Group PCI (n=10) - newborn rats, from pregnant rat submitted to remote ischemic preconditioning 24hours before delivery, that will be submitted to hypoxia/reoxygenation; Group Larg+PCI (n=10) - newborn rats, from pregnant rat treated with L-arginine and submitted to remote ischemic preconditioning 24hours before delivery, that will be submitted to hypoxia/reoxygenation. Remote ischemic preconditioning (PCI e Larg+PCI) will be done at 20th day of pregnancy (approximately 24 hours before delivery) by tourniquet on the left hind limb for 10minutes. The hypoxia/reoxygenation will be done in the offspring of all groups, except from group Ref. The offspring will be allocated, from the 1st birthday, for five minutes into the 100% CO2 chamber followed by 5 minutes with 100% O2, twice a day for three days consecutively. At the 4th day, offspring will be anesthetised with thionembutal, 30mg/kg, to perform surgical resection of the intestine, followed by euthanasia with anesthetic overdose. After macroscopic evaluation of the ischemic injury, intestines will be sectioned and terminal ileum and ascending colon segments will be separated for posterior analysis. Segments of both parts of will be fixed in buffered formalin solution 10% for histological analysis stainned by hematoxilin-eosin and immunohistochemical study for S-100 protein and specific neuronal enolasis, and other segments will be conserved in freezer 70o C , to determine malondialdehyde (MDA) for analysis of lipid peroxidation . (AU)

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