Environmental enrichment attenuates the blood brain barrier dysfunction induced by the neonatal hypoxia-ischemia.
Environmental enrichment (EE) is considered an efficient neuroprotector against neonatal hypoxia-ischemia (HI). Nevertheless, the mechanisms involved are not yet clear. In this context, the aim of this study was to investigate the effects of neonatal HI and environmental stimulation in the hippocampus of rats at 3 different time points (PND 8, 22 and 60), evaluating some aspects of BBB structure and function. Seven-day-old Wistar rats were divided into four groups: a control group maintained in a standard environment (CTSE), a control group maintained in an enrichment environment (CTEE), an HI group maintained in a standard environment (HISE) and an HI group maintained in an enrichment environment (HIEE). At the 7th postnatal day (PND), rats were submitted to the Levine-Rice model of neonatal HI. This method consists of permanent occlusion of the right common carotid artery with subsequent exposure to hypoxia. Rats from CTEE and HIEE were stimulated with environmental enrichment. The EE protocol started 24h after HI, in which pup rats with their dams were stimulated in a maintained EE (PND 8-22). Subsequently, animals were submitted to daily EE (1h/day, PND 23-60). The expression of some proteins involved in BBB structure (β-catenin, occludin, connexin-43, aquaporin-4, glut-1 and GFAP) were quantified by western blotting in the hippocampi of rats in three periods, at PND 8, 22 and 60. The BBB permeability and integrity was assessed by Evans blue staining and the immunohistochemistry for GFAP in the CA1 region of the hippocampus were also performed. The results showed an HI-induced decreased occludin expression at PND 22 and low levels of occludin, β-catenin and GFAP at PND 60 in the hippocampus of the hypoxic-ischemic rats. Interestingly, in young and adult rats, EE reversed these effects. Evans blue extravasation into the brain parenchyma confirmed the BBB dysfunction brought on by HI. No differences were observed at PND 8, probably due to the immaturity of the BBB at this age. The present study makes an important contribution to understanding the mechanism of the hypoxic-ischemic brain damage and also to presents, for the first time, the recovery of BBB dysfunction as a possible pathway for the protective effect of EE.
Programa de Pós Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: rdfisioterapia@gmail.com.
Ramiro
R
Diaz
Programa de Pós Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: patymiguel@msn.com.
Patrícia Maidana
PM
Miguel
Programa de Pós Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: bruninhaferrary@hotmail.com.
Bruna Ferrary
BF
Deniz
Programa de Pós Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: heloisadconfortim@gmail.com.
Heloísa Deola
HD
Confortim
Programa de Pós Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Departamento de Ciências Morfológicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: silvia.barbosa@ufrgs.br.
Sílvia
S
Barbosa
Departamento de Farmacologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil; Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia (IB), Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil. Electronic address: mo_padilha@hotmail.com.
Monique Culturato Padilha
MCP
Mendonça
Departamento de Farmacologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil; Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia (IB), Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil. Electronic address: hofling@unicamp.br.
Maria Alice
MA
da Cruz-Höfling
Programa de Pós Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Departamento de Ciências Morfológicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: lenir.orlandi@ufrgs.br.
Lenir Orlandi
LO
Pereira
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D051401:Aquaporin 4 / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000378:metabolism / Q000473:pathology*; D017630:Connexins / Q000378:metabolism; D004195:Disease Models, Animal; D004777:Environment; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology* / Q000503:physiopathology*; D008297:Male; D062793:Occludin / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D051401:Aquaporin 4; D017630:Connexins; D005904:Glial Fibrillary Acidic Protein; D051272:Glucose Transporter Type 1; D062793:Occludin
Brain; Endothelial junctions; Enriched environment; Neonatal asphyxia; Neuroprotection; Perinatal brain damage