You know that feeling of fullness you get after eating a large meal? Well, scientists have now discovered and mapped the signals that travel the highway between your stomach and your brain, which let your mind know that you’re satiated after a meal rich in protein. Understanding this connection is important for scientists in strategizing future approaches to prevent and treat obesity.
A short lesson on the biology of hunger
Food intake is regulated by mu-opioid receptors (MORs.) MORs are located on neuropods (similar in architecture to neurons) that inhabit the walls of the major blood vessel that drains the blood from the gut. They have been called the gateway to drug addiction, because they bind with morphine and give positive reinforcement when activated. When these receptors are stimulated, they enhance food intake (hunger) and when blocked, they suppress food intake (resulting in a feeling of fullness, or lack of hunger.)
Researchers have found that the products of proteins which have undergone the digestion process, called peptides, have the ability to block MOR activation, resulting in a curbing of one’s appetite. These peptides function to send signals to our brains, which then trigger a signal that is sent back down to our gut, which prompts our intestine to release glucose, effectively suppressing our desire to eat.
So protein is good for lowering appetite, but the conclusions don’t stop there
In addition to the possibilities of improving obesity treatments, these findings present an opportunity for scientists to better understand how foodborne viruses can access the brain.
What happens when you feed someone the rabies virus
Since the brain understands what’s going on within the gut in real time due to a constant interchange of messages, researchers decided to monitor the colons of subjects with the rabies virus to see how the brain is consequently affected. Rabies is able to spread throughout the body by first infecting the neurons, and is regularly used in lab experiments to get a better visualisation of neuronal connections.
Since neuropods are so similar to neurons in their mechanics, it was amazing to note that the virus infected the gut cells that contained neuropods. This means that the virus then had access to the brain-gut highway, and a direct access to the nervous system. This might also imply how other viruses could gain access to the nervous system as well.
Undoubtedly there will be more to learn as scientists continue to develop a complete map of the brain-gut highway.