To further understand An overlooked gut microbiota product, a 2018 rodent study found:
“Microbial metabolites short-chain fatty acids (SCFAs) have been implicated in gastrointestinal functional, neuroimmune regulation, and host metabolism, but their role in stress-induced behavioural and physiological alterations is poorly understood
SCFAs are primarily derived from fermentation of dietary fibres, and play a pivotal role in host gut, metabolic and immune function. All these factors have previously been demonstrated to be adversely affected by stress.
Administration of SCFAs to mice undergoing psychosocial stress alleviated enduring alterations in anhedonia and heightened stress-responsiveness, as well as stress-induced increases in intestinal permeability.
SCFA treatment alleviated psychosocial stress-induced alterations in reward-seeking behaviour, and increased responsiveness to an acute stressor and in vivo intestinal permeability. In addition, SCFAs exhibited behavioural test-specific antidepressant and anxiolytic effects, which were not present when mice had also undergone psychosocial stress.”
https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1113/JP276431 “Short-chain fatty acids: microbial metabolites that alleviate stress-induced brain–gut axis alterations”
One way researchers advance science is to relate aspects of their findings to previous studies. That approach works, but may miss items that weren’t covered in previous research.
This study fed specific quantities of three SCFAs – acetate, butyrate, and propionate – apparently due to previous research findings. If other SCFAs produced by gut microbiota were ignored – like crotonate (aka unsaturated butyrate) – how would that approach advance science?
I found this study from its citation in Harnessing endogenous defenses with broccoli sprouts.