Biology subjects

Breton, J.

Publications and source records attributed to Breton, J..

8 recordsLinked to original sources

bioRxiv2026

Role of the gut microbiota in the remodelling of the jejunal, colonic, hepatic and blood proteomes in a mouse model of Anorexia Nervosa

Background: Anorexia nervosa (AN) is a typical form of eating disorder characterized by a severe body weight loss, a fear of gaining weight and dysmorphophobia. This disorder is associated with both psychiatric comorbidities and multi-organ dysfunctions. Increasing evidence suggests a role of the gut microbiota in the onset or maintenance of AN. Although a dysbiosis has been reported in patients with AN, the physiological consequences of this dysbiosis remain poorly documented. To gain further insight into the role of the gut microbiota in the pathophysiology of AN, we used the murine Activity-based Anorexia (ABA) model and compared the remodelling of the jejunal, colonic, hepatic and blood proteomes occurring in male mice with intact gut microbiota, as well as in gut microbiota-depleted animals. Results: We observed a significant proteome remodelling in several organs in response to the ABA model. More than 250 proteins involved in energy metabolism, catabolic processes, lipid metabolism, ghrelin regulation, and immune functions were found to show altered abundance in ABA mice compared to control mice. We observed in addition in the blood of ABA mice a significant increase in the level of circulating proteasome. By comparing mice treated or not with antibiotics, we identified 75 proteins whose regulation in ABA mice is gut-microbiota dependent. The other identified proteins were similarly affected in ABA mice with intact or depleted gut microbiota, suggesting that these factors are mainly regulated by food starvation and physical activity, and not directly by the gut microbiota. We finally confirmed that ORM2, a protein identified as significantly decreased in the plasma of ABA mice, is also decreased in the blood of patients suffering from AN. Conclusion: Our results demonstrate that the Activity-Based Anorexia model is associated with an extensive proteome remodelling in several organs and tissues. We highlight in addition that some of these targets are regulated in a gut microbiota-dependent manner, thereby reinforcing the hypothesis of a role of the gut microbiota in Anorexia Nervosa. Together, our study provides a valuable resource to better delineate the impact of undernutrition and maladaptive physical activity on the proteome of various organs and the role of the gut bacteria in the pathophysiology of Anorexia Nervosa.

pathology↗

bioRxiv2026

Smooth muscle cell estrogen receptor alpha promotes arterial stiffness in the absence of estradiol

BackgroundClinical evidence supports a greater impact of arterial stiffening in cardiovascular mortality in women versus men. Arterial stiffness increases across the menopausal transition, implicating a role of the loss of estrogens in arterial stiffening, but mediating mechanisms remain unclear. MethodsThe role of estradiol and smooth muscle cell (SMC) estrogen receptor alpha (ER) in arterial stiffening, by aortic pulse wave velocity (PWV), was assessed in 3 models: (1) the loss of estradiol in young, female mice comparing sham surgery or bilateral ovariectomy (OVEX) {+/-} estradiol, (2) the impact of sham versus OVEX surgery in young, female SMC-ER-intact and SMC-ER-knockout (KO) littermates, and (3) arterial stiffening during natural aging by comparing young and aged, female and male SMC-ER-intact and SMC-ER-KO littermates. Mechanistic pathways were assessed using histological assessment of aortic fibrosis and elastin degradation, aortic MMP expression, and atomic force microscopy. ResultsOVEX increased PWV and aortic medial fibrosis, with no impact on elastin integrity, in young female mice. Arterial stiffening and fibrosis were prevented in OVEX mice that were supplemented with estradiol. OVEX-induced arterial stiffening in SMC-ER-intact female mice was prevented in SMC-ER-KO littermates. In this model, OVEX was also associated with increased aortic medial fibrosis without changes in elastin integrity. Aging from 3 to 18 months significantly increased PWV in female and male SMC-ER-intact mice. Aging-induced stiffening was fully prevented in female and partially prevented in male SMC-ER-KO mice. SMC-ER contributes to aging-associated arterial stiffening by sex-specific mechanisms, including elastin degradation in females and phenotypic changes in SMC stiffness and probability to form cellular adhesions in males. Circulating estradiol was significantly decreased in serum from aged compared with young female mice. ConclusionsThese findings support that SMC-ER contributes to arterial stiffening in female and male mice in situations where the vasculature is exposed to low levels of estradiol.

physiology↗

bioRxiv2025

Behavioral Opportunism and Altered Dopamine Dynamics in Mice Exposed to Early Life Adversity

Early life adversity (ELA) confers risk for reward-related psychopathologies. These risks may stem from adaptations optimizing reward pursuit in anticipation of unreliable, resource poor environments. One rational adaptation to poor, unreliable environments is Behavioral Opportunism: updating expectations more slowly and acting vigorously only when reward is immediately available. To systematically test the impact of ELA on behavioral strategies and underlying reward processing mechanisms, we exposed mice to resource restriction (limited bedding and nesting materials for 7 days) to manipulate the reliability and quality of early life care. Subsequently, we tested adults reward learning and decision making in a two-arm bandit task and recorded dopamine signaling using dLight1.2 fiber photometry in the nucleus accumbens core. Exposure to ELA led to poorer choice discrimination, impaired learning, and decreased adaptation to changes in reward availability. Furthermore, ELA mice were slower to choose between levers but were faster to retrieve immediately available rewards when delivered, consistent with a strategy of behavioral opportunism. Dopamine signaling predicted behavior in both rearing conditions, and its fluctuations were strongly predictive of faster retrieval in ELA mice and an increased likelihood of choice repetition, implying that aberrant dopamine signals underlie slowed learning and vigorous action for immediately available rewards. To understand key features of maternal interactions driving these effects, we used home cage video monitoring to quantify maternal behaviors, continuously, across early life. We found that specific experiential outcomes, such as maternal kicking, intensified behavioral opportunism in adults, predicting poorer bandit task performance beyond the group effect of ELA. Behavioral opportunism provides an explanatory framework for interpreting altered reward processing and reward pursuit in adulthood for individuals exposed to ELA.

animal behavior and cognition↗

bioRxiv2025

Glutamine alters the response to stress in mice with diet-induced obesity in a sex-dependent manner.

RationalePatients with class III obesity often suffer from irritable bowel syndrome (IBS) while obesity and IBS share common pathophysiological mechanisms such as altered intestinal barrier function and gut microbiota dysbiosis. Oral glutamine (Gln) supplementation previously showed beneficial effects on gut barrier function in a sex-dependent manner and reduced abdominal pain in IBS patients. Thus, we assessed the sex-dependent response to an oral Gln supplementation in mice with diet-induced obesity and subjected to a chronic restraint stress to mimic IBS. MethodsMale (M) and female (F) C57BL/6 mice received a high fat diet (HFD; 60% kcal from fat) during 14 weeks (W14) and were subjected or not to a restraint stress (S) for the 4 last days. From W12, mice received or not Gln in drinking water (2g/kg/day; n=12/group). Plasma corticosterone, body composition, glucose tolerance (OGTT), intestinal permeability, inflammatory markers in colonic and white adipose tissues, cecal microbiota and short-chain fatty acid (SCFA) composition have been assessed. Within each sex, groups were compared by Kruskal-Wallis test or a 1-way ANOVA test. ResultsIn M-HFD mice, chronic restraint stress was associated with a better glucose tolerance (-15,46% AUC) and a reduced fasting glycemia that was not observed in F-HFD mice. Gln partially prevented body weight loss, reduced plasma resistin, plasma corticosterone and colonic permeability in female stressed obese mice. In male stressed obese mice, Gln limited lean mass loss, reduced colonic permeability and Ccl2 mRNA level in the subcutaneous adipose tissue. Chronic restraint stress and Gln modified cecal microbiota in both sexes but cecal SCFA composition only in male mice. In particular, stress induced an increased abundance of Pseudomonadota in male mice that was partially restored after Gln supplementation. In addition, cecal total SCFA were reduced in Gln-supplemented stressed HFD male mice compared to unstressed HFD mice. In female HFD mice, stress associated to Gln supplementation increased the abundance of Thermodesulfobacteriota and reduced colonic expression of Cxcr3 mRNA. ConclusionsChronic restraint stress has beneficial effects on glycemia control in male HFD mice without additive effects of Gln supplementation. By contrast, Gln reduces stress-induced corticosterone level and body weight loss only in females. These data, as well as the differential impact of Gln on intestinal permeability and gut microbiota according to the sex, deserves further investigations to decipher the underlying mechanisms.

pathology↗

bioRxiv2025

Characterisation of changes in the gut microbiota associated with eating disorders

BackgroundEating disorders are serious pathologies that often begin in adolescence or young adulthood and persist for a significant period of time, with a strong negative impact on patients quality of life and mortality. The etiological origins of eating disorders are complex and involve both biological, psychological and societal factors. The gut microbiota was recently proposed as one of the potential factors involved in eating disorders. To gain a better understanding of the potential role of the gut microbiota in these diseases, we used 16S rRNA sequencing to compare the composition of the faecal microbiota of patients with all typical forms of eating disorders, i.e. anorexia nervosa, bulimia nervosa or binge-eating disorder, with that of healthy individuals. ResultsOur results demonstrate that each type of eating disorder is associated with a specific gut bacterial signature. We observed, for example, a decrease in the relative abundances of Agathobacter and Romboutsia genera and an increase in Pseudomonas in patients with anorexia, while patients with binge-eating disorder exhibit a decrease in the relative abundances of Akkermansia and Intestinimonas and an increase in Streptococcus, Eggerthella and Proteus. We also highlight a heterogeneity of gut microbiota composition in different subcategories of eating disorders, such as restricting versus binge-purge type anorexia or typical versus atypical binge-eating disorder. By focusing on the comorbidities reported by patients, we finally identified several bacterial taxa, such as Acidaminococcus and Eggerthella, whose level correlates with the occurrence of anxiety or depressive-like symptoms. ConclusionsTogether, our work demonstrates that eating disorders are associated with specific changes in gut microbiota composition and highlight the necessity to finely stratify patients to identify robust microbial signatures. In addition, we identified bacterial taxa correlating with comorbidities and decreased quality of life reported by patients. Our results now pave the way for determining the predictive value of the abundance of these taxa on the duration of the pathology or on the likelihood of relapse. They also constitute a valuable resource to further demonstrate the causal role of the gut microbiota in the onset or chronicisation of eating disorders.

microbiology↗

bioRxiv2025

Nociceptin Orphanin F/Q Pathways are Dysregulated by Stress and Modulate Reward Learning and Motivation Across Species

Nociceptin orphanin F/Q has been implicated in stress-related depressive phenotypes. Specifically, exposure to chronic stressors upregulates nociceptin receptors (NOPR), whereas NOPR antagonism has anti-depressant/anti-anhedonic effects. The mechanisms underlying these effects remain, however, unclear. Here, we investigated the role of NOPR in depressive phenotypes alongside potentially prohedonic effects of NOPR antagonism across species. In Study 1, we evaluated whether exposure to early-life adversity (ELA) upregulated ventral tegmental area (VTA) and striatal prepronociceptin (Pnoc) gene expression in adult mice. In Study 2, we tested whether chronic social defeat altered Pnoc gene expression in reward-related regions. To establish whether direct NOPR modulation is implicated in reward-related behaviors, in Study 3, we assessed whether NOPR antagonism alters reward learning in rats. Finally, in Study 4, we tested whether NOPR antagonism boosts motivation among depressed humans. ELA induced anhedonic behavior and increased Pnoc expression in the VTA; in females (but not males), ELA increased Pnoc expression in the dorsal striatum (Study 1). Furthermore, chronic stress reduced Pnoc-expressing cells in the VTA, dorsal striatum and prefrontal cortex and susceptible rats showed reduced VTA NOPR gene (Oprl1)-expressing cells (Study 2). In a behavioral assay, a single 30-mg dose of a NOPR antagonist (BTRX-246040) boosted reward learning in rats (Study 3). Finally, in depressed humans, relative to placebo, 8-week treatment with BTRX-246040 increased incentive motivation (Study 4). Collectively, our findings indicate that chronic stressors alter Pnoc and mRNA levels of Pnoc-expressing cells in a sex-selective and region-specific manner impacting reward structures, and that NOPR antagonism shows anti-anhedonic properties.

neuroscience↗

bioRxiv2024

Sex-dependent effects of a glutamine supplementation on metabolic disorders, intestinal barrier function and gut microbiota in mice with diet-induced obesity.

RationaleObesity is often associated with sex-dependent metabolic complications, in which altered intestinal barrier function and gut microbiota contribute. Glutamine (Gln) supplementation previously showed beneficial effects on gut barrier function and glycemic control. We thus aimed to characterize in mice the sex-dependent effects of a Gln supplementation during high fat diet induced obesity. MethodsMale and female C57BL/6 mice received a standard (SD) or high fat diet (HFD; 60% kcal from fat) during 14 weeks (W14). From W12, mice received or not Gln in drinking water (2g/kg/day; n=12/group). Body composition, glucose tolerance, insulin sensitivity, intestinal permeability, colonic expression of 44 genes encoding factors involved in inflammatory response and gut barrier function, cecal microbiota and inflammatory/endocrine adipose response have been assessed. Data were analyzed using t-test or Mann-Whitney test (HFD effect), and two-way ANOVA (HFD x Gln) followed by Bonferroni post-tests. ResultsIn both male and female mice, Gln supplementation failed to improve body weight and body composition. However, Gln reduced glucose intolerance in HFD males (AUC reduced by 14.57%, p<0.05) that was associated to a partial restoration of plasma resistin and insulin and to a trend for a limitation of adipose inflammatory response. In males, Gln did not affect gut microbiota composition and colonic response. To the opposite, in females fed HFD, Gln supplementation led to gut microbiota changes (increase of Bacteroidota and Pseudomonadota phyla; increase of Muribaculaceae and Tannerellaceae families), increased colonic inflammatory markers (TNF, IL-1{beta}, TLR4, Myd88, Irf3) that were associated to increased inflammatory response in subcutaneous adipose tissue and increased HOMA-IR. ConclusionsHigh fat diet mice exhibit sex-dependent response to glutamine supplementation with protective effects in males and harmful effects in females. The role of gut microbiota should be deeply deciphered in further investigations.

pathology↗

bioRxiv2021

Adolescent rats extend help to outgroup members, highlighting a neural network for group identity categorization.

Prosocial behavior, in particular helping others in need, occurs preferentially in response to the perceived distress of ones own group members, or ingroup. The development of neural mechanisms underlying social selectivity towards ingroup members are not well established. Here, we used a rat helping behavior test to explore the development and neural basis of ingroup bias for prosocial behavior in adolescent rats. We previously found that adult rats selectively help others from their own social group, and that this selectivity is associated with activation in reward and motivation circuits. Surprisingly, we found that adolescent rats helped both ingroup and outgroup members, evidence suggesting that ingroup bias emerges in adulthood. Analysis of brain-wide neural activity, indexed by expression of the early-immediate gene c-Fos, revealed increased activity for ingroup members across a broad set of regions, which was congruent for adults and adolescents. However, adolescents showed reduced hippocampal and insular activity, and increased orbitofrontal cortex activity compared to adults. Adolescent rats who did not help trapped others also demonstrated increased amygdala connectivity. Together, these findings demonstrate that biases for group-dependent prosocial behavior develop with age in rats and suggest that specific brain regions contribute to this prosocial selectivity, overall pointing to possible targets for the functional modulation of ingroup bias. One Sentence SummaryProsocial selectivity increases with age in parallel with hippocampal and insular activation, providing insight into the neural classification of group membership.

neuroscience↗