Limosilactobacillus reuteri abundance linked to increased tameness and oxytocin in selectively bred mice
Background
Animal domestication profoundly alters behavior, particularly increasing tameness. While genetic factors contribute to traits like active tameness (motivation to approach humans), their low heritability suggests significant non-genetic influences. The gut microbiota is a prime candidate, known for its role in the gut-brain axis and influence on brain function. Understanding these microbial contributions could offer novel insights into behavioral modulation and the domestication process, addressing gaps in purely genetic explanations for complex behavioral traits.
Study Design
Researchers conducted shotgun metagenomic analyses on faecal samples from 80 mice (10 males and 10 females from two tamed and two nonselected groups). These mice were derived from a genetically heterogeneous wild-derived stock, selectively bred for active tameness. To test causality, a pyruvate-secreting L. reuteri strain was administered to nonselected mice. Primary endpoints included assessment of active tameness, measurement of blood oxytocin concentrations, and plasma pyruvate levels to investigate potential mechanistic pathways.
Results
Tamed mice exhibited markedly higher levels of active tameness compared to nonselected controls, accompanied by elevated blood concentrations of oxytocin and pyruvate. While overall taxonomic and functional diversity of the gut microbiota remained largely unchanged, a significant finding emerged: the abundance of Limosilactobacillus reuteri was significantly increased in the tamed mice. This specific microbial shift was a key differentiator. > Administration of a pyruvate-secreting L. reuteri strain to nonselected mice successfully elevated blood oxytocin levels and enhanced active tameness, although plasma pyruvate levels were not increased by this intervention. These findings strongly suggest a direct association between L. reuteri and behavioral modulation, potentially mediated through oxytocin-related pathways, offering mechanistic insights into microbial contributions to animal domestication.
Key Findings
- Tamed mice showed markedly higher active tameness and elevated blood oxytocin and pyruvate levels.
- Abundance of
Limosilactobacillus reuteriwas significantly increased in tamed mice. - Administering
L. reuterito nonselected mice elevated blood oxytocin and enhanced active tameness. - Plasma pyruvate levels were not increased by
L. reuteriadministration, suggesting a more complex pathway. L. reuteriis associated with behavioral modulation, potentially via oxytocin-related pathways.
Why It Matters
This study provides compelling evidence that specific gut microbes, like Limosilactobacillus reuteri, can directly influence complex behaviors such as tameness, potentially via the oxytocin pathway. Modulating gut microbiota could offer a novel strategy for influencing behavioral traits, moving beyond traditional genetic selection. For biohackers and researchers, this opens avenues for exploring probiotic interventions to impact mood, social behavior, or stress responses, given oxytocin's broad roles. While preclinical, it suggests that targeted microbial interventions might one day be developed to enhance desirable behavioral traits in animals or even humans, though human translation requires extensive further research.
limosilactobacillus-reuteri
gut-brain-axis
tameness
oxytocin
pyruvate
domestication