BRS5 → BRS6 — Gut–Vagal Influence on Stress-Axis Regulation
Vagal and microbial signals from BRS5 can modify HPA-axis and autonomic regulation in BRS6.
Dependency
Gut afferent traffic, especially vagal signalling, can change stress-axis responsiveness and autonomic tone. BRS6 remains the owner of cortisol rhythm and metabolic allocation; BRS5 supplies a peripheral modulatory input.
Principal Routes
| Route | Contribution to BRS6 | Relationship |
|---|---|---|
| Vagal/ENS signalling | Can alter HPA-axis and autonomic responses | Conditional; key evidence is preclinical |
| Autonomic coupling (HRV-related) | Associates vagal tone with stress neurobiology | Conditional; not gut-specific by itself |
Network Interpretation
This is a peripheral-to-stress-axis route. It should not be collapsed into BRS5 → BRS1. Transmitter effects, if any, remain BRS5 → BRS6 → BRS1 or other mediated paths.
Boundary and Evidence Status
Bravo et al. show vagus-dependent HPA-related effects in mice. Thayer et al. meta-analyse heart-rate variability and neuroimaging; that supports autonomic–brain coupling, not a demonstrated gut intervention on BRS6. The dependency is retained as conditional.
Supporting Evidence
- Bravo et al., 2011 — Mouse study in which gut bacteria modulated stress-related central signalling via the vagus nerve.
- Thayer et al., 2012 — Meta-analysis linking heart-rate variability to neuroimaging markers of stress and health; not a gut-metabolite trial.