By Fatma Younis
Scientists have discovered a slow dopamine signal that travels from the gut to the brain, teaching us to enjoy foods that make us feel good. The finding, published in Nature, explains why coffee is widely loved despite its strong, bitter taste.
Slow Dopamine Signal from Gut to Brain
Researchers at the University of California, San Francisco identified a dopamine pathway that enables the brain to learn about the nutrient content of food. While fast-acting dopamine pathways were known, the slow-acting side had remained elusive until now.
Key Neural Pathway Identified
A specific circuit linking dopamine-producing neurons in the ventral tegmental area (VTA) to the anterior basolateral amygdala (aBLA) plays a central role. This pathway helps the brain associate a food's flavour with its nutritional value.
Experiments with Mice
In experiments, glucose water or a milkshake-like liquid was delivered directly into the stomachs of mice, bypassing taste receptors. Nutrients triggered sustained dopamine release in the basolateral amygdala. When these dopamine-releasing nerve fibres were artificially stimulated, the mice developed a preference for a calorie-free flavour.
Implications for Food Preferences
The VTA dopamine neurons are key to updating food preferences when new nutritional information arrives. The research reveals how the brain connects flavour information with delayed gut signals, raising the possibility that food preferences could one day be adjusted with targeted treatments. Senior author Zachary Knight noted that once the brain associates coffee's flavour with the caffeine uplift, coffee starts to taste better.
