Transferring the blues: Depression-associated gut microbiota induces neurobehavioural changes in the rat.
Level 5 - mechanism / opinion, no new human data
Animal interventional model (fecal microbiota transplantation in rats) combined with human case-control sampling
PubMed 27491067 · doi:10.1016/j.jpsychires.2016.07.019
What was done
Researchers recruited 34 patients with major depression and 33 matched healthy controls. They measured inflammatory and endocrine markers (cytokines, CRP, salivary cortisol, and plasma lipopolysaccharide-binding protein) using ELISA, and plasma tryptophan and kynurenine using HPLC. Fecal samples underwent 16S rRNA sequencing. Fecal microbiota from a subgroup of depressed patients and controls was transferred via oral gavage into microbiota-deficient rats to evaluate neurobehavioral and physiological effects.
What was found
The abstract reports no numerical values, confidence intervals, or statistical test results. It qualitatively reports that major depression was associated with decreased gut microbiota richness and diversity. Fecal microbiota transplantation from depressed donors to microbiota-depleted rats induced depressive-like features, including anhedonia, anxiety-like behaviors, and alterations in tryptophan metabolism.
Why it matters
This study provides experimental evidence in an animal model suggesting a potential causal role for gut microbiota in the neurobehavioral and metabolic features of depression.
Limits
The abstract provides no quantitative data or effect sizes. Causal mechanisms were tested exclusively in a rodent model, limiting direct generalizability to human depression. The human cohort was small (67 total participants), and the exact number of donor samples used for transplantation as well as the number of recipient rats were not reported in the abstract.
Cited by
- partial Fecal microbiota transplants from depressed human donors into healthy rats induce depressive behavior in the rats, and transplants from healthy humans into depressed rats reverse their depression.