High gestational folic acid supplementation prevents hypoxia-ischemia-induced caspase-3 augmenting without changing synapsin and H3 methylation levels in the rat hippocampus.

Perinatal asphyxia is a peripartum event that can cause permanent sequelae to the newborns, affecting the brain development. Recently, it has been demonstrated that epigenetics mechanisms play an important role in this injury and that folic acid (FA) supplementation during pregnancy can affect these epigenetics modifications as well as gene expression. We have identified both positive and negative effects of FA treatment in rats submitted to a model of neonatal hypoxia-ischemia (HI). Considering that FA supplementation is already used in pregnant women and that HI occurs in the peripartum period, this study was designated to evaluate how gestational FA supplementation and neonatal HI affect: apoptosis (caspase-3) and expression of synaptic proteins (synapsin and PSD-95) and the methylation of histone H3 lysine (K) 4 and 27 in the rat hippocampus. Pregnant Wistar rats were divided according to the diets: standard (SD), supplemented with 2 mg/kg of FA or with 20 mg/kg of FA. HI procedure was performed at the 7th PND. Protein expression and H3 methylation were evaluated at the 60th PND in the rats' hippocampus. Neonatal HI increased caspase-3 expression decreased synapsin expression and reduced H3K4me2, -me3 and H3K27me2, -me3 in the ipsilateral hippocampus. FA only prevented the augment in caspase-3 expression. In conclusion, neonatal HI caused lasting effects on caspase-3-mediated cell death (prevented by the FA) and synaptic proteins in the rats' hippocampus. This is the first study to show that histone modifications may contribute to these pathological findings in the hippocampus of HI animals.

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.

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.

Folic acid supplementation during pregnancy prevents cognitive impairments and BDNF imbalance in the hippocampus of the offspring after neonatal hypoxia-ischemia.

Folic acid (FA) supplementation (400 µg/day) has been recommended during pregnancy to prevent neural tube defects. However, in some countries, flours are required to be fortified with FA, possibly increasing the levels of this vitamin in pregnant women. Our previous studies have evidenced a dual effect of the FA treatment in a rat model of neonatal hypoxia-ischemia (HI). Aiming to better correlate with humans, this paper evaluated the effects of two different levels of FA supplementation during pregnancy on memory parameters and neuronal survival and plasticity in the hippocampus of rats submitted to the neonatal HI. During pregnancy, female Wistar rats received one of these diets: standard (SD), supplemented with 2 mg/kg of FA or with 20 mg/kg of FA. At the 7th PND, rats suffered the HI procedure. At the 60th PND rats were evaluated in the open field, Morris water maze, novel-object recognition and inhibitory avoidance tasks. Furthermore, neuronal density, synaptophysin densitometry and BDNF concentration were assessed in the hippocampus. Both doses of FA prevented the HI-induced memory impairments. The supplementation reversed the BDNF late increase in the hippocampus of the HI rats, but did not inhibit the neuronal death. In conclusion, FA supplementation during pregnancy prevented memory deficits and BDNF imbalance after neonatal HI. These findings are particularly relevant because neuroprotection was achieved even in the high level of FA supplementation during pregnancy, indicating that this intervention would be considered secure for the offspring development.

Folic Acid Can Contribute to Memory Deficit and Na+, K+- ATPase Failure in the Hippocampus of Adolescent Rats Submitted to Hypoxia- Ischemia.

Recent findings have demonstrated a dual effect of the folic acid (FA) supplementation on the nervous system of rats. We found that FA treatment prevented memory impairment and Na(+), K(+)- ATPase inhibition in the striatum and cortex in adult rats that suffered neonatal hypoxia-ischemia (HI). However, spatial memory deficit has been associated with FA supplementation. In the present study we investigated the role of FA supplementation on spatial memory and Na(+), K(+)-ATPase activity in the hippocampus, as well as on morphologic alterations in adolescent rats submitted to neonatal HI. Wistar rats of both sexes at postnatal day (PND) 7 were submitted to Levine-Rice HI procedure. Intraperitoneal doses of FA were administered immediately before HI and repeated daily until the maximum PND 40. Hippocampal volume and striatum area were estimated and Na(+), K(+)-ATPase activity in the hippocampus was measured at PND 31. Also, the performance of the animals in the water maze was assessed and Na(+), K(+)-ATPase activity measured again at PND 52. Interestingly, HI and FA resulted in spatial memory deficits in the Morris water maze and the Na(+), K(+)-ATPase activity was impaired at PND 31 in HI rats which received FA. Additionally, Na(+), K(+)-ATPase activity in adulthood showed a decrease after HI and a recovery in supplemented animals. Hippocampal and striatal atrophy were partially reversed by FA. To conclude, the present results support the hypothesis that FA supplementation during development contributes to memory deficits caused by HI and Na(+), K(+)-ATPase failure in adolescent rats, although, in adulthood, FA has been effective in reversing enzymatic activity in the hippocampus.

Folic acid prevents behavioral impairment and Na(+), K(+) -ATPase inhibition caused by neonatal hypoxia-ischemia.

Folic acid plays an important role in neuroplasticity and acts as a neuroprotective agent, as observed in experimental brain ischemia studies. The aim of this study was to investigate the effects of folic acid on locomotor activity, aversive memory and Na(+),K(+)-ATPase activity in the frontal cortex and striatum in animals subjected to neonatal hypoxia-ischemia (HI). Wistar rats of both sexes at postnatal day 7 underwent HI procedure and were treated with intraperitoneal injections of folic acid (0.011 µmol/g body weight) once a day, until the 30th postnatal day. Starting on the day after, behavioral assessment was run in the open field and in the inhibitory avoidance task. Animals were sacrificed by decapitation 24 h after testing and striatum and frontal cortex were dissected out for Na(+),K(+)-ATPase activity analysis. Results show anxiogenic effect in the open field and an impairment of aversive memory in the inhibitory avoidance test in HI rats; folic acid treatment prevented both behavioral effects. A decreased Na(+),K(+)-ATPase activity in striatum, both ipsilateral and contralateral to ischemia, was identified after HI; a total recovery was observed in animals treated with folic acid. A partial recovery of Na(+),K(+)-ATPase activity was yet seen in frontal cortex of HI animals receiving folic acid supplementation. Presented results support that folic acid treatment prevents memory deficit and anxiety-like behavior, as well as prevents Na(+),K(+)-ATPase inhibition in the striatum and frontal cortex caused by neonatal hypoxia-ischemia.