Multi-hit early life adversity affects gut microbiota, brain and behavior in a sex-dependent manner
Introduction
The multi-hit hypothesis (or cumulative stress hypothesis) proposes that neuropsychiatric disorders may be precipitated by a combination of two or more major adverse events in particular during development (Maynard et al., 2001, McEwen, 1998, Nederhof and Schmidt, 2012). Subjects exposed to one or more childhood adversities are more likely to become depressed following exposure to stress at adulthood than subjects without early adversity (Chapman et al., 2004, Nemeroff, 2016). Maternal infection and postnatal exposure to psychological stress or traumas have been found to represent important environmental risk factors for the development of psychiatric disorders, including autism, schizophrenia, anxiety-disorders and depression (Brown, 2011, Brown et al., 2014, Nemeroff, 2016). According to the multiple-hit hypothesis, prenatal infection could render the offspring more vulnerable to the deleterious effects of a second postnatal stimulus, such as stress. Previous findings have comforted this hypothesis in animal models combining prenatal inflammation and adolescent or adult stress exposure (Deslauriers et al., 2013, Giovanoli et al., 2013, Monte et al., 2017). However, the impact of prenatal inflammation combined with an early post-natal stress remains underexplored.
The mechanisms underlying the long-term behavioral effects of early adversity are still unclear. A large body of evidence suggests that the medial prefrontal cortex (mPFC), a brain area involved in the regulation of emotional behavior, plays a major role in mediating the effects of early-life stress (Arnsten, 2009, Ulrich-Lai and Herman, 2009). Recent work has demonstrated that the gut microbiota affects gene expression in the mPFC (Gacias et al., 2016, Hoban et al., 2017, Hoban et al., 2016). Gastrointestinal alterations during early-life, notably gut microbiota dysbiosis and loss of barrier function, can disturb brain development and lastingly impair gut-brain communication (Borre et al., 2014, Hsiao et al., 2013, Kim et al., 2017). In particular, maternal immune activation and maternal separation (MS) have been shown to produce intestinal defects such as visceral pain and increased intestinal permeability in association with behavioral outcomes (see Labouesse et al., 2015, O’Mahony et al., 2011 for reviews). Animals exposed to early-life immune or psychological stress also exhibit gut dysbiosis (Amini-Khoei et al., 2019, Bailey and Coe, 1999, Moya-Pérez et al., 2017, Murakami et al., 2017, O’Mahony et al., 2009, Pusceddu et al., 2015). Moreover, numerous studies using maternal immune activation or MS models have shown that microbiota-directed interventions such as probiotic treatments or fecal transplantation modulate brain and behavior, especially stress-related behaviors (De Palma et al., 2015, Giovanoli et al., 2016, Hsiao et al., 2013, Kim et al., 2017, Mattei et al., 2014, Moya-Pérez et al., 2017). Importantly, it has been reported that gut microbiota composition differs according to sex both in animals and humans (Fransen et al., 2017, Hollister et al., 2014, Jašarević et al., 2016, Markle et al., 2013). However, sex differences in gut microbiota in a context of early adversity remain underexplored. Indeed, most of the studies use males and the few studies involving males and females often pool data from both sexes (De Palma et al., 2015, El Aidy et al., 2017, Hsiao et al., 2013, Riba et al., 2018). This issue, which merits further investigation, is of particular importance with respect to the gender differences observed in the prevalence of psychiatric disorders. To support this notion, autism spectrum disorders are more prevalent in men (Werling and Geschwind, 2013), whereas women are more susceptible to anxiety and depression (Steel et al., 2014).
In the present study, we hypothesized that early adversity differentially affects the gut microbiota in males and females and that these differential effects may underlie the sex-related differences observed at the behavioral level. To test this hypothesis, we developed a mouse model of multifactorial early adversity combining prenatal inflammation (lipopolysaccharide (LPS) injection), post-natal MS and unpredictable chronic mild stress (UCMS) in dams and we investigated emotional behavior, mPFC gene expression and gut microbiota composition in male and female offspring (Fig. 1).
Section snippets
Effects of multi-hit early adversity on offspring’s body weight
LPS injection on E17 induced significant hypothermia in dams (t(15) = 4.98, p < 0.001), indicating that bacterial immune activation was effective (Supplementary Fig. S1). There was no significant effect of prenatal LPS on pup body weight on post-natal day (PND)2 (Supplementary Fig. S2A). However, the combination of prenatal LPS and MS (early adversity) significantly decreased the body weight of male pups at PND15 in comparison with control pups (males, t(15) = 2.46, p = 0.003; females, t
Discussion
Several studies have reported sex differences in gut microbiota composition in both humans and animals (Hollister et al., 2014, Markle et al., 2013). There is a growing number of studies investigating the role of the gut-brain axis, especially gut microbiota, in the regulation of stress-related emotional behaviors in animal models of early-life adversity. However, it is not clear whether early stress differentially affects the gut microbiota between males and females (Jašarević et al., 2017,
Animals
Experiments were approved by the Bioethical committee of the University of Bordeaux (N° 50120186-A) according to the European legislation (Directive 2010/63/EU, 22 September 2010). Mice were maintained in a 12-h light/12-h dark cycle (lights on at 0800 h) in a temperature-controlled room (22 °C) with free access to food and water, unless otherwise mentioned. Gestant female C3H/HeNRj mice (n = 30) purchased (Janvier Labs, Le Genest Saint Isle, France) at gestational day 2 were individually
Acknowledgements
This work was supported by the University of Bordeaux, INRA and AVIESAN Immunology, Hematology and Pneumology. M.R. was supported by a stipend of the French Ministry of Research. We warmly thank Céline Monot & Karine Le Roux for technical support and logistics with the microbiological analyses. We are grateful to the INRA MIGALE bioinformatics platform (http://migale.jouy.inra.fr) for providing computational resources. We also thank the Genotoul Get-PlaGe sequencing platform, and Thierry
References (90)
- et al.
On the role of corticosterone in behavioral disorders, microbiota composition alteration and neuroimmune response in adult male mice subjected to maternal separation stress
Int. Immunopharmacol.
(2019) - et al.
Chronic gastrointestinal inflammation induces anxiety-like behavior and alters central nervous system biochemistry in mice
Gastroenterology
(2010) - et al.
Microbiota and neurodevelopmental windows: implications for brain disorders
Trends Mol. Med.
(2014) - et al.
Endogenous regulation of visceral pain via production of opioids by colitogenic CD4(+) T cells in mice
Gastroenterology
(2014) The environment and susceptibility to schizophrenia
Prog. Neurobiol.
(2011)- et al.
Microbial reconstitution reverses maternal diet-induced social and synaptic deficits in offspring
Cell
(2016) - et al.
Adverse childhood experiences and the risk of depressive disorders in adulthood
J. Affect. Disord.
(2004) - et al.
Combination of prenatal immune challenge and restraint stress affects prepulse inhibition and dopaminergic/GABAergic markers
Prog. Neuropsychopharmacol. Biol. Psychiatry
(2013) - et al.
Sex-specific effects of early life stress on social interaction and prefrontal cortex dendritic morphology in young rats
Behav. Brain Res.
(2016) - et al.
Prenatal infection leads to ASD-like behavior and altered synaptic pruning in the mouse offspring
Brain. Behav. Immun.
(2017)
Specific neurodevelopmental damage in mice offspring following maternal inflammation during pregnancy
Neuropharmacology
Antibiotic-induced microbiota perturbation causes gut endocannabinoidome changes, hippocampal neuroglial reorganization and depression in mice
Brain. Behav. Immun.
Compositional and functional features of the gastrointestinal microbiome and their effects on human health
Gastroenterology
Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders
Cell
Effects of FG7142 and immobilization stress on the gene expression in the neocortex of mice
Neurosci. Res.
Psychotropic effects of Lactobacillus plantarum PS128 in early life-stressed and naïve adult mice
Brain Res.
Minocycline rescues decrease in neurogenesis, increase in microglia cytokines and deficits in sensorimotor gating in an animal model of schizophrenia
Brain. Behav. Immun.
Two-hit model of schizophrenia induced by neonatal immune activation and peripubertal stress in rats: Study of sex differences and brain oxidative alterations
Behav. Brain Res.
Involvement of TLR4 in the long-term epigenetic changes, rewarding and anxiety effects induced by intermittent ethanol treatment in adolescence
Brain Behav. Immun.
Maternal deprivation induces depressive-like behaviours only in female rats
Behav. Brain Res.
Bifidobacterium CECT 7765 modulates early stress-induced immune, neuroendocrine and behavioral alterations in mice
Brain. Behav. Immun.
Mismatch or cumulative stress: toward an integrated hypothesis of programming effects
Physiol. Behav.
Paradise lost: the neurobiological and clinical consequences of child abuse and neglect
Neuron
Early life stress alters behavior, immunity, and microbiota in rats: implications for irritable bowel syndrome and psychiatric illnesses
Biol. Psychiatry
Adolescent mice show anxiety- and aggressive-like behavior and the reduction of long-term potentiation in mossy fiber-CA3 synapses after neonatal maternal separation
Neuroscience
Long-lasting changes in behavioural and neuroendocrine indices in the rat following neonatal maternal separation: gender-dependent effects
Brain Res.
Effect of lactobacillus rhamnosus HN001 in pregnancy on postpartum symptoms of depression and anxiety: a randomised double-blind placebo-controlled trial
EBioMedicine
Juvenile stress induces a predisposition to either anxiety or depressive-like symptoms following stress in adulthood
Eur. Neuropsychopharmacol. J. Eur. Coll. Neuropsychopharmacol.
Stress signalling pathways that impair prefrontal cortex structure and function
Nat. Rev. Neurosci.
Exposure to juvenile stress exacerbates the behavioural consequences of exposure to stress in the adult rat
Int. J. Neuropsychopharmacol.
A novel function for Egr4 in posterior hindbrain development
Sci. Rep.
Maternal separation disrupts the integrity of the intestinal microflora in infant rhesus monkeys
Dev. Psychobiol.
A comparison of normalization methods for high density oligonucleotide array data based on variance and bias
Bioinforma. Oxf. Engl.
Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve
Proc. Natl. Acad. Sci.
Elevated maternal C-reactive protein and autism in a national birth cohort
Mol. Psychiatry
Ribosomal Database Project: data and tools for high throughput rRNA analysis
Nucl. Acids Res.
Antidepressant effect of optogenetic stimulation of the medial prefrontal cortex
J. Neurosci.
Microbiota and host determinants of behavioural phenotype in maternally separated mice
Nat. Commun.
Digging and marble burying in mice: simple methods for in vivo identification of biological impacts
Nat. Protoc.
Cognitive and emotional alterations are related to hippocampal inflammation in a mouse model of metabolic syndrome
PloS One
Gene expression omnibus: NCBI gene expression and hybridization array data repository
Nucl. Acids Res.
Serotonin transporter genotype modulates the gut microbiota composition in young rats, an effect augmented by early life stress
Front. Cell. Neurosci.
Emotional memory impairments in a genetic rat model of depression: involvement of 5-HT/MEK/Arc signaling in restoration
Mol. Psychiatry
Pre- and neonatal exposure to lipopolysaccharide or the enteric metabolite, propionic acid, alters development and behavior in adolescent rats in a sexually dimorphic manner
PloS One
The Impact of gut microbiota on gender-specific differences in immunity
Front. Immunol.
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