Stress-sensitive neural circuits change the gut microbiome via duodenal glands, 2024, Chang et al.

Stress-sensitive neural circuits change the gut microbiome via duodenal glands
Hao Chang; Matthew H. Perkins; Leonardo S. Novaes; Feng Qian; Tong Zhang; Peter H. Neckel; Simon Scherer; Ruth E. Ley; Wenfei Han; Ivan E. de Araujo

Negative psychological states impact immunity by altering the gut microbiome. However, the relationship between brain states and microbiome composition remains unclear. We show that Brunner's glands in the duodenum couple stress-sensitive brain circuits to bacterial homeostasis. Brunner's glands mediated the enrichment of gut Lactobacillus species in response to vagus nerve stimulation.

Cell-specific ablation of the glands markedly suppressed Lactobacilli counts and heightened vulnerability to infection. In the forebrain, we mapped a vagally mediated, polysynaptic circuit connecting the central nucleus of the amygdala to Brunner's glands. Chronic stress suppressed central amygdala activity and phenocopied the effects of gland lesions. Conversely, excitation of either the central amygdala or parasympathetic vagal neurons activated Brunner's glands and reversed the effects of stress on the gut microbiome and immunity.

The findings revealed a tractable brain-body mechanism linking psychological states to host defense.


Link | PDF (Cell) [Open Access]

 

Highlights

• Secretion of mucin from the glands of Brunner promotes gut Lactobacilli proliferation

• Central amygdala neurons stimulate Brunner’s glands via vagal nerves

• Stress inhibits the central amygdala, thereby suppressing Brunner’s glands activity

• Impaired gland activity compromises Lactobacilli populations and host immunity

 

Every time they talk about stress, it all depends on what they even mean by stress. This simply does not translate to a common and standard notion of what stress means in every day life. What 'stresses' some people inspires others, and vice versa.

I guess this can all pretty much be summed as stress meaning subjectively unpleasant circumstances, to the point of restraint torture. Or whatever. Problem is, this is extremely far from the principle of "all other things being equal". They are not studying one general phenomenon. They are mostly just torturing animals and calling it equivalent to... whatever.

This kind of research is basically pointless and will never amount to anything.

 

I agree that studying 'stress' in mice is pretty gross.

But I think this result may tell us something very important - it may already have been known but ignored. It suggests that just being unwell or suffering from any stimulus that can set off vagal activity can change the microbiome, and gives a plausible mechanism.

Which means that any studies finding shifts in microbiota in an illness such as ME/CFS need to consider seriously that the shift may be secondary not just to drugs taken for symptoms but to just being ill. Totally unsurprising but useful to see confirmation that it can happen.