Early-life stress, microbiota, and brain development: probiotics reverse the effects of maternal separation on neural circuits underpinning fear expression and extinction in infant rats

AbstractExposure to early life stress (ELS) during childhood or prenatally increases the risk of future psychiatric disorders. The effect of stress exposure during the neonatal period is less well understood. In preterm infants, exposure to invasive procedures is associated with altered brain development and future stress responses suggesting that the neonatal period could be a key time for the programming of mental health. Previous studies suggest that ELS affects the hypothalamic epigenome, making it a good candidate to mediate these effects. In this study, we used a mouse model of early life stress (modified maternal separation; MMS). We hypothesised MMS would affect the hypothalamic transcriptome and DNA methylome, and impact on adult behaviour. MMS involved repeated stimulation of pups for 1.5 h/day, whilst separated from their mother, from postnatal day (P) 4–6. 3’mRNA sequencing and DNA methylation immunoprecipitation (meDIP) sequencing were performed on hypothalamic tissue at P6. Behaviour was assessed with the elevated plus, open field mazes and in-cage monitoring at 3–4 months of age. MMS was only associated with subtle changes in gene expression, but there were widespread alterations in DNA methylation. Notably, differentially methylated regions were enriched for synapse-associated loci. MMS resulted in hyperactivity in the elevated plus and open field mazes, but in-cage monitoring revealed that this was not representative of habitual hyperactivity. ELS has marked effects on DNA methylation in the hypothalamus in early life and results in stress-specific hyperactivity in young adulthood. These results have implications for the understanding of ELS-mediated effects on brain development.

Download Full-text

Early-Life Stress Modulates Gut Microbiota and Peripheral and Central Inflammation in a Sex-Dependent Manner

International Journal of Molecular Sciences ◽

10.3390/ijms22041899 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1899 ◽

Cited By ~ 1

Author(s):

Hae Jeong Park ◽

Sang A. Kim ◽

Won Sub Kang ◽

Jong Woo Kim

Keyword(s):

Gut Microbiota ◽

Relative Abundance ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Early Life Stress ◽

Female Rats ◽

Rrna Gene ◽

Dependent Manner ◽

Male And Female Rats

Recent studies have reported that changes in gut microbiota composition could induce neuropsychiatric problems. In this study, we investigated alterations in gut microbiota induced by early-life stress (ELS) in rats subjected to maternal separation (MS; 6 h a day, postnatal days (PNDs) 1–21), along with changes in inflammatory cytokines and tryptophan-kynurenine (TRP-KYN) metabolism, and assessed the differences between sexes. High-throughput sequencing of the bacterial 16S rRNA gene showed that the relative abundance of the Bacteroides genus was increased and that of the Lachnospiraceae family was decreased in the feces of MS rats of both sexes (PND 56). By comparison, MS increased the relative abundance of the Streptococcus genus and decreased that of the Staphylococcus genus only in males, whereas the abundance of the Sporobacter genus was enhanced and that of the Mucispirillum genus was reduced by MS only in females. In addition, the levels of proinflammatory cytokines were increased in the colons (IFN-γ and IL-6) and sera (IL-1β) of the male MS rats, together with the elevation of the KYN/TRP ratio in the sera, but not in females. In the hippocampus, MS elevated the level of IL-1β and the KYN/TRP ratio in both male and female rats. These results indicate that MS induces peripheral and central inflammation and TRP-KYN metabolism in a sex-dependent manner, together with sex-specific changes in gut microbes.

Download Full-text

Maternal Separation as Early-Life Stress Causes Enhanced Allergic Airway Responses by Inhibiting Respiratory Tolerance in Mice

The Tohoku Journal of Experimental Medicine ◽

10.1620/tjem.246.155 ◽

2018 ◽

Vol 246 (3) ◽

pp. 155-165 ◽

Cited By ~ 3

Author(s):

Ryusuke Ouchi ◽

Tasuku Kawano ◽

Hitomi Yoshida ◽

Masato Ishii ◽

Tomomitsu Miyasaka ◽

...

Keyword(s):

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Early Life Stress ◽

Airway Responses

Download Full-text

Maternal separation in rodents: a journey from gut to brain and nutritional perspectives

Proceedings of The Nutrition Society ◽

10.1017/s0029665119000958 ◽

2019 ◽

Vol 79 (1) ◽

pp. 113-132 ◽

Cited By ~ 3

Author(s):

Marion Rincel ◽

Muriel Darnaudéry

Keyword(s):

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Human Subjects ◽

Early Life Stress ◽

Long Term Effects ◽

Early Life Adversity ◽

Critical Window ◽

Beneficial Impact ◽

The Impact

The developmental period constitutes a critical window of sensitivity to stress. Indeed, early-life adversity increases the risk to develop psychiatric diseases, but also gastrointestinal disorders such as the irritable bowel syndrome at adulthood. In the past decade, there has been huge interest in the gut–brain axis, especially as regards stress-related emotional behaviours. Animal models of early-life adversity, in particular, maternal separation (MS) in rodents, demonstrate lasting deleterious effects on both the gut and the brain. Here, we review the effects of MS on both systems with a focus on stress-related behaviours. In addition, we discuss more recent findings showing the impact of gut-directed interventions, including nutrition with pre- and probiotics, illustrating the role played by gut microbiota in mediating the long-term effects of MS. Overall, preclinical studies suggest that nutritional approaches with pro- and prebiotics may constitute safe and efficient strategies to attenuate the effects of early-life stress on the gut–brain axis. Further research is required to understand the complex mechanisms underlying gut–brain interaction dysfunctions after early-life stress as well as to determine the beneficial impact of gut-directed strategies in a context of early-life adversity in human subjects.

Download Full-text

Downregulation of kainate receptors regulating GABAergic transmission in amygdala after early life stress is associated with anxiety-like behavior in rodents

Translational Psychiatry ◽

10.1038/s41398-021-01654-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jonas Englund ◽

Joni Haikonen ◽

Vasilii Shteinikov ◽

Shyrley Paola Amarilla ◽

Tsvetomira Atanasova ◽

...

Keyword(s):

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Early Life Stress ◽

Kainate Receptors ◽

Gabaergic Transmission ◽

Cortical Afferents ◽

Functional Modulation ◽

Endogenous Activity ◽

Dependent Mechanism

AbstractEarly life stress (ELS) is a well-characterized risk factor for mood and anxiety disorders. GABAergic microcircuits in the amygdala are critically implicated in anxiety; however, whether their function is altered after ELS is not known. Here we identify a novel mechanism by which kainate receptors (KARs) modulate feedforward inhibition in the lateral amygdala (LA) and show that this mechanism is downregulated after ELS induced by maternal separation (MS). Specifically, we show that in control rats but not after MS, endogenous activity of GluK1 subunit containing KARs disinhibit LA principal neurons during activation of cortical afferents. GluK1 antagonism attenuated excitability of parvalbumin (PV)-expressing interneurons, resulting in loss of PV-dependent inhibitory control and an increase in firing of somatostatin-expressing interneurons. Inactivation of Grik1 expression locally in the adult amygdala reduced ongoing GABAergic transmission and was sufficient to produce a mild anxiety-like behavioral phenotype. Interestingly, MS and GluK1-dependent phenotypes showed similar gender specificity, being detectable in male but not female rodents. Our data identify a novel KAR-dependent mechanism for cell-type and projection-specific functional modulation of the LA GABAergic microcircuit and suggest that the loss of GluK1 KAR function contributes to anxiogenesis after ELS.

Download Full-text

Abstract 335: Vascular Histone Deacetylase Mediates Early Life Stress-Induced Endothelial Dysfunction

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.33.suppl_1.a335 ◽

2013 ◽

Vol 33 (suppl_1) ◽

Author(s):

Dao H Ho ◽

Jennifer S Pollock

Keyword(s):

Endothelial Dysfunction ◽

Nadph Oxidase ◽

Protein Expression ◽

Histone Deacetylase ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Chromatin Modification ◽

Early Life Stress ◽

Mrna Levels

Chromatin remodeling is an important factor in the etiology of vascular pathologies. Also, early life stress (ELS) is linked to increased risk of vascular disease in adults. We used maternal separation with early weaning (MSEW) to study mechanisms of ELS-mediated adult vascular dysfunction in male C57BL/6J mice. Litters were subjected to maternal separation 4h/day (postnatal day (PD) 2-5) and 8h/day (PD6-16), and weaned at PD17. Control (CON) litters were undisturbed until weaning at PD21. Subsequent experiments were performed at 12 weeks old. MSEW blunted aortic ACh-mediated vasorelaxation (MSEW: 68% vs CON: 90%, p=0.01), while SNP-induced vasorelaxation was similar in CON and MSEW aortae. Apocynin (300 μM) and superoxide dismutase (100 U/mL) normalized MSEW-induced endothelial dysfunction. We hypothesize that ELS induces aortic endothelial dysfunction by increasing NADPH oxidase expression and/or decreasing nitric oxide synthase 3 (NOS3) expression. Aortic protein expression of NADPH oxidase subunit p67 was elevated in MSEW mice (45% increase from CON, n=11, p=0.02). NOS3 protein expression and NOS3 serine 1177 phosphorylation was not different between groups, indicating that NOS3 activation by phosphorylation does not contribute to ELS-induced endothelial dysfunction. We further hypothesize that chromatin modification mediates ELS-induced endothelial dysfunction. Aortic mRNA expressions of 84 chromatin modification enzymes (methyltransferases, demethylases, acetyltransferases, deacetylases) were assessed by qRT-PCR. Only histone deacetylase (HDAC) 1, 6 and 9 mRNA levels were significantly upregulated in MSEW aortae compared to CON (17%, 29% and 67% increase, respectively, p<0.05). However, only HDAC 9 protein expression was elevated in MSEW aortae (2 fold increase from CON, n=6, p=0.01). Accordingly, histone 3 lysine acetylation was slightly decreased in MSEW aortae (16% decrease from CON, n=6, p = 0.06). Pretreatment of aortae with an HDAC inhibitor, trichostatin A (TSA), normalized ACh-induced vasorelaxation in MSEW mice (MSEW: 68% vs MSEW + TSA: 88%, p=0.02), while not affecting ACh-induced vasorelaxation in CON mice. We conclude that ELS induces endothelial dysfunction, most likely, through an HDAC 9-mediated pathway.

Download Full-text

Abstract 008: Early Life Stress Induces Renal Pro-inflammatory Immune Responses

Hypertension ◽

10.1161/hyp.66.suppl_1.008 ◽

2015 ◽

Vol 66 (suppl_1) ◽

Author(s):

Carmen De Miguel ◽

Dao H Ho ◽

Analia S Loria ◽

Ijeoma Obi ◽

Jennifer S Pollock

Keyword(s):

Immune Response ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Immune Cell ◽

Early Life Stress ◽

Adult Rats ◽

Activation Markers ◽

Ifn Gamma ◽

Inflammatory Status

We previously reported that maternal separation (MatSep), an animal model of early life stress, sensitizes rats to pro-hypertensive stimuli in adulthood. We hypothesized that MatSep induces a renal pro-inflammatory immune response. Immune cell populations and expression of cytokines were assessed by magnetic bead isolation, FACS analysis, ELISA and RT-PCR in adult male MatSep and normally-reared littermate control rats. Circulating and renal mononuclear or T cell numbers were similar between control and MatSep rats (n=4-11/group, p>0.05). Both groups presented similar percentages of circulating macrophages and T H , T C , and T reg cells (n=4, p>0.05). However, the percentage of circulating B cells was significantly decreased in MatSep rats (23.7±1.2% vs. 20.1±0.7%; n=4, p<0.05). Pro-inflammatory cytokine IL-1Beta was significantly elevated in kidneys from MatSep rats (4.4±0.5 vs. 7.9±1.0 pg/mg prot; n=7-8/group; p<0.05). However, IFN-gamma, IL-6, and IL-4 were not different between control and MatSep rats. To further assess the immune system in MatSep and control rats, we acutely challenged adult rats with lipopolysaccharide (LPS; 2 mg/kg; i.v., 14 h). LPS significantly elevated renal expression of pro-inflammatory chemokine receptors (CCR3, CCR4, CXCR4), cytokines (IFN-gamma, CCL3, CCL4, IL-16), and activation markers (CD40, CD40lg) in MatSep rats (4 to 6 fold increase; n=5/group, p<0.05), suggesting that MatSep induces an exaggerated pro-inflammatory renal immune response to LPS. In conclusion, early life stress induces a renal pro-inflammatory status in adulthood that leads to sensitization to further immune challenges. Funded by P01 HL 69999 to JSP, NIH T32 DK007545 to CDM, F32 HL 116145 to DHH and K99/R00 HL 111354 to ASL.

Download Full-text

Abstract P219: Mice Exposed To Early Life Stress Have Impaired Autonomic Activity At Baseline And In Response To Acute Stress In Adulthood

Hypertension ◽

10.1161/hyp.76.suppl_1.p219 ◽

2020 ◽

Vol 76 (Suppl_1) ◽

Author(s):

Megan K Rhoads ◽

Kasi C McPherson ◽

Keri M Kemp ◽

Bryan Becker ◽

Jackson Colson ◽

...

Keyword(s):

Cardiovascular Disease ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Acute Stress ◽

Low Frequency ◽

Early Life Stress ◽

Total Power ◽

Increased Risk ◽

Inactive Period

Early life stress (ELS) is an independent risk factor for the development of cardiovascular disease in adulthood in both humans and rodent models. Maternal separation and early weaning (MSEW), a model of ELS, produces mice with an increased risk of cardiovascular dysfunction in adulthood, despite resting blood pressures (BP), heart rates (HR), and body weights comparable to normally reared controls. Autonomic regulation of HR and BP is an important component of the homeostatic response to stress but has not been investigated in MSEW mice. We hypothesized that exposure to MSEW impairs autonomic function at baseline and in response to an acute psychosocial stressor in adult male mice. C57Bl/6J litters were randomly assigned to MSEW or normally reared control conditions. MSEW litters were separated from dams for 4 h on postnatal days (PDs) 2-5, 8 h on PDs 6-16, and weaned at PD 17. Control litters were undisturbed until weaning at PD 21. At 9 weeks old, telemeters were implanted in MSEW (n=16) and control mice (n=12). During cage switch stress (CSS), mice were moved to a soiled, unfamiliar cage for 4 h. HR, systolic BP (SBP), diastolic BP (DBP), and activity (monitored by telemetry) were similar between control and MSEW mice at baseline and during CSS (p>0.05, 2-way ANOVA). Spectral analysis of HR, SBP, and DBP indicated that HR variability (HRV) total power was lower in MSEW mice during the 12 h inactive period compared to controls (18.9±1.1 ms 2 vs. 27.5±3.1 ms 2 ; p=0.0033, 2-way ANOVA) at baseline. HRV low frequency (LF) power was also lower during the 12 h inactive period in MSEW mice (4.2±0.4 ms 2 vs.6.6±0.9 ms 2 ; p=0.009). At baseline, 12 h and 24 h DBP variability LF/high frequency (HF) ratio, normalized LF, and normalized HF power were lower in the MSEW group (p<0.05, all comparisons). During the final 90 minutes of CSS, MSEW mice had lower HRV total, LF, and HF power compared to controls (p<0.05); although HR, SBP, DBP, and activity remained similar between groups. These data suggest that MSEW mice have impaired autonomic control of HR and DBP and lack the ability to robustly respond and recover from an acute stressor. Reduced responsiveness of the autonomic nervous system may contribute to the increased risk of cardiovascular disease development in adult mice exposed to MSEW.

Download Full-text

Early life stress due to repeated maternal separation alters the working memory acquisition brain functional network

Stress ◽

10.1080/10253890.2020.1777974 ◽

2020 ◽

pp. 1-9

Author(s):

María Banqueri ◽

Alba Gutiérrez-Menéndez ◽

Marta Méndez ◽

Nélida M. Conejo ◽

Jorge L. Arias

Keyword(s):

Working Memory ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Early Life Stress ◽

Functional Network ◽

Brain Functional Network ◽

Memory Acquisition

Download Full-text

Maternal separation-induced increases in vascular stiffness are independent of circulating angiotensinogen levels

Journal of Applied Physiology ◽

10.1152/japplphysiol.00703.2019 ◽

2020 ◽

Vol 129 (1) ◽

pp. 58-65

Author(s):

Timothy M. Mahanes ◽

Margaret O. Murphy ◽

An Ouyang ◽

Frederique B. Yiannikouris ◽

Bradley S. Fleenor ◽

...

Keyword(s):

High Fat Diet ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Early Life Stress ◽

Normal Diet ◽

Vascular Stiffness ◽

High Fat ◽

Vascular Contractility ◽

Circulating Levels

This study demonstrates that there was no correlation between circulating levels of angiotensinogen (AGT) and the development of vascular stiffness in rats exposed to early-life stress and fed a normal diet. This study also shows that early-life stress-induced hypersensitive vascular contractility to angiotensin II in rats fed a high-fat diet is independent of circulating levels of AGT and occurs without further progression of vascular stiffness. Our data show that early-life stress primes the adipose tissue to secrete AGT in a sex- and species-independent fashion.

Download Full-text