In a examine of fruit fly (Drosophila) larvae, a global crew of researchers has found how swallowing meals is linked to the discharge of the feel-good chemical serotonin within the mind – providing new perception into how and why animals eat.
If the identical mechanisms are current in people, then this may very well be a captivating perception into our personal drive to eat foods and drinks.
Scientists mapped the intestine’s enteric nervous system within the fruit fly intimately, and their findings shed new mild on the important act of swallowing: a conduct the researchers describe as “arguably the single most salient decision that an animal has to make”.
“We wanted to gain a detailed understanding of how the digestive system communicates with the brain when consuming food,” says neuroscientist Michael Pankratz, from the College of Bonn in Germany.
“In order to do this, we had to understand which neurons are involved in this flow of information and how they are triggered.”
The researchers actually went above and past in the middle of their examine: they fastidiously lower one of many larvae into hundreds of tiny slices earlier than photographing them below high-powered microscopes, mapping the paths of neurons and the connections between them.
A 3-dimensional mannequin was constructed from these images through laptop software program, resulting in the invention of a organic mechanism generally known as a stretch receptor, as within the esophagus, which connects the mouth to the abdomen.
The receptor is linked to 6 particular neurons within the larva’s mind, which get details about the swallowing motion, and – crucially – what’s being eaten. If good meals goes down the pipe, the mind pumps out a reward.
“[The neurons] can detect whether it is food or not and also evaluate its quality,” says neuroscientist Andreas Schoofs, from the College of Bonn.
“They only produce serotonin if good quality food is detected, which in turn ensures that the larva continues to eat.”
Fruit flies have below 200,000 neurons in complete, in comparison with the 100 billion or so within the human mind. Nonetheless, the complexity in these hundreds of nerve cells means they’ll act as a scaled-down model of the human physique, which is simpler to catalog – and right here, revealing a primary driver behind a course of each animal must survive.
The following stage is to see whether or not or not the identical map of neurons and launch of serotonin is current in different animals, together with people. We’ve extra organic similarities with fruit flies than you may assume, however quite a lot of scaling up will likely be required on this strategy to know if this feel-good issue when consuming is one in every of them.
“We don’t know enough at this stage about how the control circuit in humans actually works,” says Pankratz. “There is still years of research required in this area.”
The analysis is printed in Present Biology.
