Differential brain responses to gradual intragastric nutrient infusion and gastric balloon distension: A role for gut peptides?
Level 3 - non-randomized controlled study
Within-subject experimental physiological crossover study in healthy humans.
PubMed 27639359 · doi:10.1016/j.neuroimage.2016.09.032
What was done
Fifteen healthy volunteers underwent H2 15O-PET brain imaging on two separate days in counterbalanced order to compare neural responses between gradual intragastric nutrient infusion (to maximal satiation) and mechanical gastric balloon distension (to individual pain threshold). Investigators measured regional brain activity, alongside plasma concentrations of ghrelin and peptide YY 3-36 (PYY 3-36), to evaluate the gut-brain signaling differences between nutrient ingestion and mechanical stretch.
What was found
The abstract does not report specific numerical values, effect sizes, or test statistics. Qualitatively, mechanical balloon distension progressively activated pain-responsive regions and deactivated exteroceptive sensory and default mode network areas. Nutrient infusion progressively deactivated pain neuromatrix regions and the orbitofrontal cortex, while activating the midbrain. Plasma PYY 3-36 increased and ghrelin decreased during nutrient infusion only, and decreasing ghrelin concentrations correlated with increasing midbrain neural activity.
Why it matters
The study suggests a neural mechanism explaining why healthy individuals tolerate large volumes of ingested food without pain: nutrient-induced physiological signals actively suppress pain matrix activity and modulate midbrain reward and pain-control regions, rather than mirroring the visceral pain pathways triggered by purely mechanical distension.
Limits
The sample size is small (n = 15) and restricted to healthy volunteers, limiting generalizability to clinical populations with functional gastrointestinal or eating disorders. The abstract provides no quantitative metrics, confidence intervals, or exact p-values.
Cited by
- context Stretching the stomach turns off the release of the hunger hormone ghrelin.