Environmental stimulation improves performance in the ox-maze task and recovers Na+,K+-ATPase activity in the hippocampus of hypoxic–ischemic rats

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.

Section: Bbb Dysfunction In the Neonatal Himentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Environmental enrichment attenuates the blood brain barrier dysfunction induced by the neonatal hypoxia‐ischemia

Díaz

Miguel

Deniz

et al. 2016

“…We can to propose that these rudimentary responses are preserved due the importance of sensorimotor responses to neonates’ survival, probably involved in a spontaneous recovery after the HI injury (Farkas et al, 2009; Trollmann and Gassmann, 2009). Other point to be considered is that the Levine‐Vannucci HI model is well‐recognized by the cognitive deficits observed, especially, in adult rats (Carletti et al, 2012, 2016; Deniz et al, 2018; Miguel et al, 2015, 2017; Pereira et al, 2007; Rojas et al, 2013, 2015) but there is no consensus about motor deficits in this model (Lubics et al, 2005; Sanches et al, 2012; Van der Kooij et al, 2010) Taken that neonatal reflexes are almost all correlated to sensorimotor function it is possible that this HI model is not the best one to evaluate motor function. This limitation should be considered in this study that has its main focus on early development; future studies with adult rats can give further support for the impact of gestational FA supplementation on pup's development.…”

Section: Discussionmentioning

confidence: 99%

“…Rats were placed at the center of the apparatus and the latency to get the first reward, the incorrect and correct number of nose pokes, and the time to complete the task (maximum of 10 min) were recorded by a blind researcher. To minimize the olfactory cues, it was put bran of the reward in all holes and the apparatus and the blocks were cleaned with 30% ethyl alcohol between rats’ tests (Rojas et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

Gestational folic acid supplementation does not affects the maternal behavior and the early development of rats submitted to neonatal hypoxia‐ischemia but the high supplementation impairs the dam's memory and the Na⁺, K⁺ ‐ ATPase activity in the pup's hippocampus

Deniz

Confortim

Deckmann

et al. 2018

Folic acid (FA) is a B‐complex vitamin important to the development of the fetus, being supplemented during pregnancy. Our recent findings showed that gestation supplementation (normal and excess doses) prevented the cognitive deficits and BDNF imbalance in adult rats that were submitted to neonatal hypoxia‐ischemia (HI). To better understand this protective effect, the present study aimed to evaluate whether FA supplementation could be related to (1) maternal behavior, memory and Na+, K+ ‐ ATPase activity in the hippocampus of the dams; (2) on somatic growth, early neurobehavioral development and Na+, K+ ‐ ATPase activity in the hippocampus of the offspring; and (3) the effects of this supplementation in pups submitted to neonatal HI. Pregnant Wistar rats were divided into three groups, according to the diet they received during gestation: standard diet (SD), supplemented with 2 mg/kg of FA (FA2 – normal dose) and supplemented with 20 mg/kg of FA (FA20 –excessive dose). At the 7th PND pups were submitted to the Levine‐Vannucci model of HI. During weaning the maternal behavior, the somatic growth and the neurobehavior development of pups were assessed. After weaning, the memory of the dams (by the Ox‐maze task) and the Na+, K+ ‐ ATPase activity in the hippocampus of both dams and offspring were evaluated. Considering the dams (1), both doses of FA did not alter the maternal behavior or the Na+, K+ ‐ ATPase activity in the hippocampus, but a memory deficit was observed in the high FA‐supplemented mothers. Considering the offspring (2), both FA doses did not affect the somatic growth or the neurobehavior development, but the FA20 pups had a decreased Na+, K+ ‐ ATPase activity in the hippocampus. The FA supplementation did not change the parameters evaluated in the HI rats (3) and did not prevent the decreased Na+, K+ ‐ ATPase activity in the hippocampus of the HI pups. These results indicate that normal FA supplementation dose does not influence the maternal behavior and memory and does not impact on the offspring early development in rats. Further studies are needed to confirm the effects of the high FA supplementation dose in the dams’ memory and in the Na+, K+ ‐ ATPase activity in the hippocampus of the offspring.

“…EE includes both voluntary physical exercise as well as components of social, cognitive and sensorimotor stimulus (Livingston‐Thomas et al, 2016). Despite the positive response of EE mitigating HI‐induced deficits on animals exposed to enriched condition after weaning (Diaz et al, 2016; Pereira et al, 2007; Rojas et al, 2015), only one study evaluated the effects of EE during the antenatal period and its effect in the offspring submitted to HI at PND 3. Gestational EE reduced apoptotic cell death as well as the astrocytic hypereactivity 48 h after the injury, possibly mediated by protein kinase B pathway activation in cortex and hippocampus.…”

Section: Lifestyle Interventions ‐ Physical Exercise and Environmentamentioning

confidence: 99%

Pregnancy as a valuable period for preventing hypoxia‐ischemia brain damage

Netto

Sanches

Odorcyk

et al. 2018

Self Cite

Neonatal brain Hypoxia-Ischemia (HI) is one of the major causes of infant mortality and lifelong neurological disabilities. The knowledge about the physiopathological mechanisms involved in HI lesion have increased in recent years, however these findings have not been translated into clinical practice. Current therapeutic approaches remain limited; hypothermia, used only in term or near-term infants, is the golden standard. Epidemiological evidence shows a link between adverse prenatal conditions and increased risk for diseases, health problems, and psychological outcomes later in life, what makes pregnancy a relevant period for preventing future brain injury. Here, we review experimental literature regarding preventive interventions used during pregnancy, i.e., previous to the HI injury, encompassing pharmacological, nutritional and/or behavioral strategies. Literature review used PubMed database. A total of forty one studies reported protective properties of maternal treatments preventing perinatal hypoxia-ischemia injury in rodents. Pharmacological agents and dietary supplementation showed mainly anti-excitotoxicity, anti-oxidant or anti-apoptotic properties. Interestingly, maternal preconditioning, physical exercise and environmental enrichment seem to engage the same referred mechanisms in order to protect neonatal brain against injury. This construct must be challenged by further studies to clearly define the main mechanisms responsible for neuroprotection to be explored in experimental context, as well as to test their potential in clinical settings.