University of Bonn researchers discover brain to fat cell communication pathway that drives pathogen avoidance learning

University of Bonn study finds that fat cells release dopamine to help the brain remember to avoid pathogenic food sources.

By: AXL Media

Published: Apr 17, 2026, 7:07 AM EDT

Source: Information for this report was sourced from University of Bonn

Uncovering the Biological Basis of Conditioned Taste Aversion

When a living organism consumes food that causes illness, the brain quickly learns to avoid that specific source in the future, a survival mechanism known as conditioned taste aversion. While the behavioral outcome is well documented, the internal communication lines that trigger this change have remained a mystery. A new study published in the journal Neuron suggests that the interaction between brain cells and fat cells is a vital component of this learning process. Researchers from the University of Bonn and University Hospital Bonn, in collaboration with Tohoku University in Japan, utilized the fruit fly Drosophila to map this complex relationship between the immune system and behavior.

The Role of Specialized Neurons in Pathogen Detection

The research team conducted experiments where fruit flies were given a choice between a harmless bacterial strain and the pathogenic Pseudomonas entomophila. Initially, the flies were attracted to the odor of the harmful bacteria; however, their innate immune systems quickly raised an alarm. According to lead researcher Ilona Grunwald Kadow, receptors located on special neurons near the fly’s throat respond to components of the bacterial cell wall. These sensors act as an early warning system, detecting the presence of life-threatening microorganisms and initiating a physiological response that links the body's physical state to the brain's decision-making centers.

The Multi-Step Neurotransmitter Loop Between Organs

The detection of pathogens triggers a specific chain reaction involving two major neurotransmitters. When the throat receptors identify harmful germs, they release octopamine, a substance closely related to adrenaline. This chemical travels through neuronal branches to a fat store located in the fly’s head. According to the study, this octopamine then prompts the fat cells to produce dopamine. This dopamine is subsequently transported back into the fly’s brain, where it activates the neuronal networks responsible for learning and triggers a persistent avoidance response. This bidirectional axis ensures that the animal is deterred by the scent of the dangerous food source in future encounters.