An Amygdalar-Vagal-Glandular Circuit Controls the Intestinal Microbiome.

Area of Science:

• Neuroscience
• Microbiology
• Immunology

Background:

• Psychological states influence gut immunity via the gut microbiome.
• The precise mechanisms linking brain activity to microbiome composition are not fully understood.

Purpose of the Study:

• To investigate the role of Brunner's glands in mediating the brain-gut-microbiome axis.
• To identify neural circuits connecting the brain to Brunner's glands and their impact on gut homeostasis.

Main Methods:

• Stimulation of abdominal vagal fibers.
• Cell-specific ablation of Brunner's glands.
• Intra-vital imaging and analysis of gut microbiome composition.
• Identification of neural circuits using neuroanatomical tracing.

Main Results:

• Brunner's glands mediate the enrichment of gut probiotics in response to vagal nerve stimulation.
• Ablation of Brunner's glands leads to dysbiosis, immunodeficiency, and increased mortality from gut infections.
• A neural circuit from the central amygdala to Brunner's glands was identified, regulating probiotic growth.

Conclusions:

• Brunner's glands act as a critical interface between brain activity and intestinal bacterial homeostasis.
• A vagal-glandular neuroimmune circuit regulates the gut microbiome, particularly Lactobacilli species.
• Targeting this circuitry offers potential for modulating the gut microbiome and related immune functions.