Maternal alcoholism and neonatal hypoxia-ischemia: Neuroprotection by stilbenoid polyphenols

Highlights

• Maternal alcoholism increases deficits induced by neonatal hypoxia-ischemia (HI).

• These impairments are counteracted by maternal supplementation with piceatannol.

• Doses used are equivalent to the piceatannol content of a single passion fruit.

• Piceatannol is neuroprotective in neonatal HI in a context of maternal alcoholism.

• Originality of the study: nutritional and transgenerational therapeutic approach.

Abstract

The impact of maternal nutrition on neurodevelopment and neonatal neuroprotection is a research topic with increasing interest. Maternal diet can also have deleterious effects on fetal brain development. Fetal exposure to alcohol is responsible for poor neonatal global development, and may increase brain vulnerability to hypoxic-ischemic encephalopathy, one of the major causes of acute mortality and chronic neurological disability in newborns. Despite frequent prevention campaigns, about 10% of women in the general population drinks alcohol during pregnancy and breastfeeding. This study was inspired by this alarming fact. Its aim was to evaluate the beneficial effects of maternal supplementation with two polyphenols during pregnancy and breastfeeding, on hypoxic-ischemic neonate rat brain damages, sensorimotor and cognitive impairments, in a context of moderate maternal alcoholism. Both stilbenoid polyphenols, trans-resveratrol (RSV − 0.15 mg/kg/day), and its hydroxylated analog, trans-piceatannol (PIC − 0.15 mg/kg/day), were administered in the drinking water, containing or not alcohol (0.5 g/kg/day). In a 7-day post-natal rat model of hypoxia–ischemia (HI), our data showed that moderate maternal alcoholism does not increase brain lesion volumes measured by MRI but leads to higher motor impairments. RSV supplementation could not reverse the deleterious effects of HI coupled with maternal alcoholism. However, PIC supplementation led to a recovery of all sensorimotor and cognitive functions. This neuroprotection was obtained with a dose of PIC corresponding to the consumption of a single passion fruit per day for a pregnant woman.

Introduction

Neonatal hypoxia–ischemia (HI) is an important socio-sanitary problem as a major cause of morbidity and mortality in human newborns (1–6/1,000 births) with a high risk of chronic motor, behavioral and neurological deficits (Robertson et al., 1989, Shankaran et al., 1991). HI is characterized by a cerebral deprivation of oxygen and glucose leading to cell death, the most affected being neurons (Northington et al., 2001, Hilario et al., 2005), which leads to sensorimotor deficits and mental retardation associated to learning abnormalities (Robertson and Finer, 1993, Aridas et al., 2014). Despite this major public health problem, the only current clinical treatment is hypothermia, which is thought to slow down neuronal cell death processes by reducing brain metabolism (Hashimoto et al., 2003, Gluckman et al., 2005, Shankaran et al.., 2005). This unique therapeutic solution does not appear sufficiently successful (44–53% of infants die or suffer moderate to severe neurological disability after hypothermia treatment (Wu and Gonzalez, 2015)) and new therapeutic approaches must be developed to possibly reverse neonatal HI sequelae. In parallel to this neonatal public health problem, despite better communication about the risks, alcohol consumption in Western countries of pregnant women has not decreased (Corrao et al., 2004). In the USA, 1 out of 12 pregnant women drink alcohol (Li et al., 2012). Maternal alcohol consumption during pregnancy and breastfeeding is well known to lead to deleterious effects on neurodevelopment. It represents the major cause of intellectual disability in neonates (Abel and Sokol, 1986), a phenomenon called fetal alcohol syndrome, which incidence is 1/500 births (Dan et al., 1992). In HI context, it has been shown in vitro, on primary neuronal cultures, that combination of ethanol, even at moderate doses, and hypoxia (0.01% ethanol during 24 h plus 0.1% O₂ during 30 min) promote synergistically neuronal death (Genetta et al., 2007). Therefore, neonatal HI in a maternal alcohol exposure context needs better investigations.

We used the classical Rice-Vannuci rat HI model (Rice et al., 1981), which briefly consists of a permanent unilateral occlusion of the common carotid artery, followed by a hypoxic episode, in post natal 7-day old (P7) pups, an age that corresponds to a full-term newborn. This HI model induces large ipsilateral striatal, hippocampal and cortical injuries (Ashwal et al., 2007), leading to sensorimotor and cognitive deficits (Lebedev et al., 2003).

The impact of maternal nutrition on neonatal neurodevelopment and on neonatal neuroprotection is a research topic with increasing interest (Loren et al., 2005, Black et al., 2015). Maternal dietary supplementation with ingestion of pomegranate juice (32, 16 or 8 μmol of polyphenols/day), which contains important quantities of polyphenols, was shown to lead to significant neuroprotection (Loren et al., 2005). In another study, in a dam supplemented with a pomegranate polyphenol extract (4.8 mg polyphenols per day, orally administered during pregnancy and after delivery), a neuroprotective effect on neonatal brain injury after HI was also observed (West et al., 2007). These authors also tested direct intraperitoneal trans-resveratrol (RSV) administration on pups. RSV injection (200 µg/kg or greater) reduced caspase-3 and calpain activation and could protect neonatal brain against HI injuries. RSV, notably found in grape skins and several types of nuts or roots is one of the most extensively studied polyphenols. It can cross the placenta (Bourque et al., 2012) and its maternal consumption during pregnancy is safe (Williams et al., 2009). Although the therapeutic properties of RSV are well documented, its bioavailability is low (<1%). Its hydroxylated analogue, trans-piceatannol (PIC), found in large quantities in the seeds of passion fruit, has a two-fold higher bioavailability (Kukreja et al., 2014). However, very few studies have been carried out with this compound and only one study has been conducted on neonatal HI (Dumont et al. (2019).

In this study, we showed that PIC maternal supplementation (0.15 mg/kg/d) was neuroprotective since brain lesion volumes were reduced and sensorimotor and cognitive abilities were preserved. Moreover, for half of the pups, no brain lesion could be detected by MRI at long term, confirming the strong neuroprotective effect of this polyphenol.

The aim of the present work was to study the effect of a maternal supplementation with RSV or PIC on HI-pup brain damage in a context of maternal alcoholism. Pregnant and nursing dams were supplemented with RSV or PIC and/or ethanol and the Rice-Vannucci rat model was used to induce HI brain injury in their P7 pups. We evaluated in vivo neonate brain damages and their evolution with noninvasive magnetic resonance imaging (MRI). Cell death and brain edema were quantified in young rats for each maternal nutritional condition. Finally, motor and behavioral studies were carried out to evaluate the effect of polyphenols on cognitive functions altered by HI event and maternal alcoholism.