Binge-like Prenatal Ethanol Exposure Causes Impaired Cellular Differentiation in the Embryonic Forebrain and Synaptic and Behavioral Defects in Adult Mice

Abstract

An embryo’s in-utero exposure to ethanol due to a mother’s alcohol drinking results in a range of deficits in the child that are collectively termed fetal alcohol spectrum disorders (FASDs). Prenatal ethanol exposure is one of the leading causes of preventable intellectual disability. Its neurobehavioral underpinnings warrant systematic research. We investigated the immediate effects on embryos of acute prenatal ethanol exposure during gestational days (GDs) and the influence of such exposure on persistent neurobehavioral deficits in adult offspring. We administered pregnant C57BL/6J mice with ethanol (1.75 g/kg) (GDE) or saline (GDS) intraperitoneally (i.p.) at 0 h and again at 2 h intervals on GD 8 and GD 12. Subsequently, we assessed apoptosis, differentiation, and signaling events in embryo forebrains (E13.5; GD13.5). Long-lasting effects of GDE were evaluated via a behavioral test battery. We also determined the long-term potentiation and synaptic plasticity-related protein expression in adult hippocampal tissue. GDE caused apoptosis, inhibited differentiation, and reduced pERK and pCREB signaling and the expression of transcription factors Pax6 and Lhx2. GDE caused persistent spatial and social investigation memory deficits compared with saline controls, regardless of sex. Interestingly, GDE adult mice exhibited enhanced repetitive and anxiety-like behavior, irrespective of sex. GDE reduced synaptic plasticity-related protein expression and caused hippocampal synaptic plasticity (LTP and LTD) deficits in adult offspring. These findings demonstrate that binge-like ethanol exposure at the GD8 and GD12 developmental stages causes defects in pERK–pCREB signaling and reduces the expression of Pax6 and Lhx2, leading to impaired cellular differentiation during the embryonic stage. In the adult stage, binge-like ethanol exposure caused persistent synaptic and behavioral abnormalities in adult mice. Furthermore, the findings suggest that combining ethanol exposure at two sensitive stages (GD8 and GD12) causes deficits in synaptic plasticity-associated proteins (Arc, Egr1, Fgf1, GluR1, and GluN1), leading to persistent FASD-like neurobehavioral deficits in mice.

Utility of the Zebrafish Model for Studying Neuronal and Behavioral Disturbances Induced by Embryonic Exposure to Alcohol, Nicotine, and Cannabis

“…In a recent study from our laboratory [4], we demonstrated in early postnatal rats that prenatal exposure to alcohol, at a relatively low concentration and for only 5 days, produces a number of drug-induced behaviors in the offspring, consistent with those described in clinical studies of children [26,[55][56][57][58][59]. These early behaviors stimulated by alcohol exposure include an increase in locomotor activity, anxiety, exploration, and alcohol-seeking behavior, and they are followed by a later increase in voluntary alcohol consumption during adolescence, consistent with other reports showing these behaviors to persist into adulthood [46,60,61]. This increase in alcohol consumption at a young age, induced by alcohol administered during pregnancy at a low concentration that increases blood alcohol to levels < 150 mg/dL, suggests that the required preference for alcohol is a conditioned response that is established prenatally [62,63].…”

Effects of Genetics and Sex on Acute Gene Expression Changes in the Hippocampus Following Neonatal Ethanol Exposure in BXD Recombinant Inbred Mouse Strains

“…Interestingly, multiple genes that were significant for a strain × treatment interaction and showed a fold-change greater than 1.5 are involved in apoptosis-related pathways and have previously been linked to FASD including Bcl2l11 [ 62 ], Dusp1 [ 62 ], Egr3 [ 62 , 63 ], Fgf1 [ 64 , 65 ] Jun [ 62 , 66 ], Pik3r1 [ 62 ] Tgfb3 [ 62 , 67 ], and Txnip [ 62 , 66 ]. Moreover, many genes that showed differential ethanol-induced gene expression changes have been previously linked to gene expression changes in the brain of B6 mice using the same ethanol exposure paradigm as used in the current study [ 62 ].…”

“…Both Irs2 and Fgf1 were up regulated in LCD males after ethanol exposure. Interestingly, studies that previously reported ethanol-induced alterations in Irs2 and Fgf1 reported down-regulation after ethanol exposure [ 64 , 129 , 130 ]. However, sex-specific increases of Irs2 in males after exposure to prenatal ethanol have also been reported [ 131 ].…”

Fetal alcohol exposure impairs learning and memory functions and elevates levels of various biochemical markers of Alzheimer's disease in the brain of 12‐month‐old rats

“…These data suggest that FAE induced spatial memory impairments in both male and female offspring. Previous studies in animal models of FAE have demonstrated a deficit in hippocampal‐dependent learning and memory that persist in the adulthood in a mouse (Brady et al, 2012; Subbanna & Basavarajappa, 2022) and a rat (Sanchez et al, 2019) models of FAE. Also, children with FAE often show verbal learning and spatial memory deficits and abnormal hippocampal functions (Dodge et al, 2019; Neil et al, 2020; Willoughby et al, 2008).…”