Evidence map›Paper›PMID 41808137›Full record

ArticleBMC medicine2026

A human-derived Bacteroides strain attenuates depressive-like behavior in a rat model of social defeat-induced stress.

Marisol I Dothard, Mariaelena Caboni, Daniel Norment, Nolan Sigmund, Sarah M Allard, Jack A Gilbert, Ekaterina Gavrish, Gabriel Al-Ghalith, Andre Der-Avakian, Philip Strandwitz

Abstract read
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In one paragraph

Article in BMC medicine, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

10 authors.

Marisol I Dothard *Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA.
Mariaelena Caboni *Holobiome, 650 Albany Street, Boston, MA, 02118, USA. mariaelena@holobiome.org.
Daniel NormentHolobiome, 650 Albany Street, Boston, MA, 02118, USA.
Nolan SigmundDepartment of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA.
Sarah M AllardScripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA.
Jack A GilbertScripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA.
Ekaterina GavrishHolobiome, 650 Albany Street, Boston, MA, 02118, USA.
Gabriel Al-GhalithHolobiome, 650 Albany Street, Boston, MA, 02118, USA.
Andre Der-AvakianDepartment of Psychiatry, University of California San Diego, La Jolla, CA, 92093, USA.
Philip StrandwitzHolobiome, 650 Albany Street, Boston, MA, 02118, USA.

Funding

National Institute of Health Small Business Innovation Research R44DK120181National Science Foundation Graduate Research Fellowship Program DGE-2038238Translational Research Institute for Space Health - Space Health Ingress Program (NASA) NNX16AO69A
6 · The paper itself

Abstract

backgroundThe gut microbiome has been linked to mood disorders via communication along the gut-brain axis. We previously found levels of fecal Bacteroides were inversely associated with brain signatures of depression in the prefrontal cortex of human subjects. Bacteroides are important human commensals, playing a keystone role in regulating the immune system and producing bioactive metabolites, like the neurotransmitter gamma-aminobutyric acid and B vitamins.

methodsTo better understand the link between Bacteroides and depression - and test a candidate novel next-generation probiotic - we administered a human-derived Bacteroides salyersiae strain, HB32, orally in rats that were subjected to the repeated social defeat model of stress-induced depression. The fecal microbiome and the prefrontal cortex transcriptome were then profiled for intervention-induced alterations.

resultsOrally delivered B. salyersiae HB32 reduced depressive-like behavior in male rats comparable to the drug ketamine, independently of the strain being administered in its viable or inactivated (iHB32) form. Mechanistically, we observed that stress-induced anhedonia required the vagus nerve for its phenotype to develop, suggesting crosstalk between the gut and the brain. In support of this, we found HB32 and iHB32, but not ketamine, rescued stress-induced differential expression patterns in the prefrontal cortex, including those related to serotonin signaling and oxidative stress. In the gut, prolonged exposure to social defeat led to broad shifts in the composition of the gut microbiome, with a predominant reduction of the endogenous Bacteroides. Administration of HB32, iHB32, and ketamine attenuated the impact of stress on the microbiome, and intake of live HB32 resulted in a significant increase of the B. salyersiae species in the fecal microbiome.

conclusionsDepressive-like behavior in male rats induced by repeated social defeat requires vagal signaling, suggesting gut-brain-axis crosstalk. In animals with an intact vagus nerve, oral administration of viable or inactivated B. salyersiae HB32 reversed behavioral changes induced by chronic stress at levels comparable to ketamine. Additionally, supplementation of HB32 and iHB32 was associated with attenuation of stress-related microbiome and prefrontal cortex transcriptional changes.

Indexed as

BacteroidesDepressionProbioticsSocial DefeatStress, PsychologicalAnimalsBehavior, AnimalDisease Models, AnimalFecesGastrointestinal MicrobiomeHumansMalePrefrontal CortexRatsRats, Sprague-DawleyDepressionGut-brain axisMicrobiomePostbioticProbiotic

Identifiers

PMID41808137
PMCPMC13088394

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LicenceCC BY-NC-ND
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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.