Gestational Iron Supplementation Improves Fetal Outcomes in a Rat Model of Prenatal Alcohol Exposure

New therapeutics for the prevention or amelioration of fetal alcohol spectrum disorders: a narrative review of the preclinical literature

Background: Ethanol consumption during pregnancy induces enduring detrimental effects in the offspring, manifesting as a spectrum of symptoms collectively termed as Fetal Alcohol Spectrum Disorders (FASD). Presently, there is a scarcity of treatments for FASD.Objectives: To analyze current literature, emphasizing evidence derived from preclinical models, that could potentially inform therapeutic interventions for FASD.Methods: A narrative review was conducted focusing on four prospective treatments: nutritional supplements, antioxidants, anti-inflammatory compounds and environmental enrichment. The review also highlights innovative therapeutic strategies applied during early (e.g. folate administration, postnatal days 4-9) or late (e.g. NOX2 inhibitors given after weaning) postnatal stages that resulted in significant improvements in behavioral responses during adolescence (a critical period marked by the emergence of mental health issues in humans).Results: Our findings underscore the value of treatments centered around nutritional supplementation or environmental enrichment, aimed at mitigating oxidative stress and inflammation, implying shared mechanisms in FASD pathogenesis. Moreover, the review spotlights emerging evidence pertaining to the involvement of novel molecular components with potential pharmacological targets (such as NOX2, MCP1/CCR2, PPARJ, and PDE1).Conclusions: Preclinical studies have identified oxidative imbalance and neuroinflammation as relevant pathological mechanisms induced by prenatal ethanol exposure. The relevance of these mechanisms, which exhibit positive feedback loop mechanisms, appear to peak during early development and decreases in adulthood. These findings provide a framework for the future development of therapeutic avenues in the development of specific clinical treatments for FASD.

Nutrient Supplementation during the Prenatal Period in Substance-Using Mothers: A Narrative Review of the Effects on Offspring Development

Substance use during pregnancy increases the risk for poor developmental outcomes of the offspring, and for substance-dependent mothers, abstaining from substance use during pregnancy is often difficult. Given the addictive nature of many substances, strategies that may mitigate the harmful effects of prenatal substance exposure are important. Prenatal nutrient supplementation is an emerging intervention that may improve developmental outcomes among substance-exposed offspring. We provide a narrative review of the literature on micronutrient and fatty acid supplementation during pregnancies exposed to substance use in relation to offspring developmental outcomes. We first discuss animal models exposed to ethanol during pregnancy with supplementation of choline, zinc, vitamin E, iron, and fatty acids. We follow with human studies of both alcohol- and nicotine-exposed pregnancies with supplementation of choline and vitamin C, respectively. We identified only 26 animal studies on ethanol and 6 human studies on alcohol and nicotine that supplemented nutrients during pregnancy and reported offspring developmental outcomes. There were no studies that examined nutrient supplementation during pregnancies exposed to cannabis, illicit substances, or polysubstance use. Implementations and future directions are discussed.

Microbiota and nutrition as risk and resiliency factors following prenatal alcohol exposure

Alcohol exposure in adulthood can result in inflammation, malnutrition, and altered gastroenteric microbiota, which may disrupt efficient nutrient extraction. Clinical and preclinical studies have documented convincingly that prenatal alcohol exposure (PAE) also results in persistent inflammation and nutrition deficiencies, though research on the impact of PAE on the enteric microbiota is in its infancy. Importantly, other neurodevelopmental disorders, including autism spectrum and attention deficit/hyperactivity disorders, have been linked to gut microbiota dysbiosis. The combined evidence from alcohol exposure in adulthood and from other neurodevelopmental disorders supports the hypothesis that gut microbiota dysbiosis is likely an etiological feature that contributes to negative developmental, including neurodevelopmental, consequences of PAE and results in fetal alcohol spectrum disorders. Here, we highlight published data that support a role for gut microbiota in healthy development and explore the implication of these studies for the role of altered microbiota in the lifelong health consequences of PAE.

Current considerations for fetal alcohol spectrum disorders: identification to intervention

PURPOSE OF REVIEW

This review highlights recent findings regarding the prevalence, public health impact, clinical presentation, intervention access and conceptualization of fetal alcohol spectrum disorders (FASDs). Despite ongoing work in prevention and identification of this population, the rates of drinking during pregnancy have increased and significant gaps remain in diagnosis and intervention.

RECENT FINDINGS

Prenatal alcohol exposure is the most common preventable cause of developmental disability in the world. Research has focused on improving diagnostic clarity, utilizing technology and neuroimaging to facilitate identification, engaging broader stakeholders (including self-advocates) to inform understanding and needs, and increasing access to effective interventions. There is an emerging focus on developmental trajectories and experiences in young and middle adulthood. Public policy advocacy has also made great strides in recent years.

SUMMARY

Increases in public awareness, greater concordance of diagnostic schema, leveraged use of novel technology, and the development of targeted interventions within a holistic, strengths-based conceptualization are important considerations for this population.

Fetal anemia and elevated hepcidin in a mouse model of fetal alcohol spectrum disorder

INTRODUCTION

Prenatal alcohol exposure (PAE) impairs offspring growth and cognition, and this is worsened by concurrent iron deficiency. Alcohol disrupts fetal iron metabolism and produces functional iron deficiency, even when maternal iron status is adequate. We used a mouse model of moderate PAE to investigate the mechanisms underlying this dysregulated iron status.

METHODS

C57BL/6J female mice received 3 g/kg alcohol daily from embryonic day (E) 8.5-17.5 and were assessed at E17.5.

RESULTS

Alcohol reduced fetal hemoglobin, hematocrit, and red blood cell counts, despite elevated erythropoietin production. Alcohol suppressed maternal hepcidin expression and the upstream iron-sensing BMP/SMAD pathway, consistent with its effects in the nonpregnant state. In contrast, alcohol elevated fetal hepcidin, although this was not accompanied by an upregulation of the BMP/SMAD or proinflammatory IL-6/STAT3 pathways. Fetal expression of hepatic genes contributing to hemoglobin synthesis and iron metabolism were unaffected by alcohol, whereas those affecting ribosome biogenesis were suppressed, suggesting a novel candidate effector for this fetal anemia.

CONCLUSION

These data confirm and extend prior observations that PAE disrupts maternal and fetal iron metabolism and impairs the fetus's ability to regulate iron status. We propose this dysregulation increases gestational iron needs and represents a conserved response to PAE.

IMPACT

Prenatal alcohol exposure causes a functional iron deficiency in a model that also impairs cognition in later life. Prenatal alcohol exposure causes fetal anemia. This fetal anemia is accompanied by elevated hepcidin and erythropoietin. Findings are consistent with prior observations that prenatal alcohol exposure increases maternal-fetal iron requirements during pregnancy.

Fetal Alcohol Spectrum Disorder and Iron Homeostasis

Prenatal alcohol exposure results in a spectrum of behavioral, cognitive, and morphological abnormalities collectively referred to as fetal alcohol spectrum disorder (FASD). FASD presents with significant phenotypic variability and may be modified by gestational variables such as maternal nutritional status. Iron serves a critical function in the development of and processes within central nervous system (CNS) structures. Gestational iron deficiency alters CNS development and may contribute to neurodevelopmental impairment in FASD. This review explores the relationship between iron deficiency and fetal alcohol spectrum disorder as described in small animal and human studies. Consideration is given to the pathophysiologic mechanisms linking iron homeostasis and prenatal alcohol exposure. Existing data suggest that iron deficiency contributes to the severity of FASD and provide a mechanistic explanation linking these two conditions.

Brain Iron and Mental Health Symptoms in Youth with and without Prenatal Alcohol Exposure

Prenatal alcohol exposure (PAE) negatively affects brain development and increases the risk of poor mental health. We investigated if brain volumes or magnetic susceptibility, an indirect measure of brain iron, were associated with internalizing or externalizing symptoms in youth with and without PAE. T1-weighted and quantitative susceptibility mapping (QSM) MRI scans were collected for 19 PAE and 40 unexposed participants aged 7.5–15 years. Magnetic susceptibility and volume of basal ganglia and limbic structures were extracted using FreeSurfer. Internalizing and Externalizing Problems were assessed using the Behavioural Assessment System for Children (BASC-2-PRS). Susceptibility in the nucleus accumbens was negatively associated with Internalizing Problems, while amygdala susceptibility was positively associated with Internalizing Problems across groups. PAE moderated the relationship between thalamus susceptibility and internalizing symptoms as well as the relationship between putamen susceptibility and externalizing symptoms. Brain volume was not related to internalizing or externalizing symptoms. These findings highlight that brain iron is related to internalizing and externalizing symptoms differently in some brain regions for youth with and without PAE. Atypical iron levels (high or low) may indicate mental health issues across individuals, and iron in the thalamus may be particularly important for behavior in individuals with PAE.