Part 10/15:
These circulating cytokines, notably TNF-alpha and IL-6, can reach the brain, activating microglia, sensitizing neural circuits involved in pain, mood, and cognition, and fueling anxiety and depression. Conversely, stress and trauma can alter microbiome composition, creating a bidirectional feedback loop exacerbating inflammation and neural sensitization.
Animal studies corroborate this: microbiome transplants from stressed mice induce anxiety-like behaviors in naive hosts, highlighting the profound influence of gut ecology on neural and immune responses. Human studies link reduced short-chain fatty acids—beneficial microbial metabolites—with increased amygdala activity and impaired fear extinction, elucidating the neurocircuitry involved.