When many people think of the nervous system, they think of the brain. After all, we are taught that the body cannot feel hot or cold, pain or comfort without a signal from the all-important brain. Yet scientists today are looking at other parts of the nervous system, called “peripheral” nervous systems, which regulate body functions on their own. One important area is the gut, where the gut nervous system responds to nutrients and keeps the body healthy.
At the Joint Annual Meeting, held this past July in New Orleans, scientists discussed the role of the nutrients and the gut nervous system during a symposium titled “Nonruminant Nutrition Symposium: Nutrient and neuroendocrine regulation of gastrointestinal function.” The goal of the symposium was to share research and better understand how working with the gut nervous system can improve digestion in livestock.
David Bravo, a scientist from feed additive company Pancosma, wrote a summary of the symposium for the Journal of Animal Science. Bravo explained that the gut is “a sensory organ and detection system with various key players regulating its function.”
In the first symposium presentation, University of Melbourne researchers John Furness discussed how the gut nervous system, which is made up of around 500 million neurons, regulates bodily functions like water absorption. Just as the tongue can sense different flavors, the special endocrine cells in the gut can sense different nutrients. Furness and Poole explained how the presence of certain nutrients can stimulate the release of more than 20 hormones. When the gut nervous system and endocrine system are working correctly, the body absorbs nutrients and moves waste out. Unfortunately, said Furness and Poole, the system can be disrupted by surgery or illness.
The second presenter, researcher Jackie Wood from Ohio State University, focused on the immune system as one of the “key players” that affect gut function. Wood discussed the “brain-in-the-gut” theory, which proposes that animals evolved sensory neurons in the gut to avoid a long and unreliable connection to the central nervous system. Wood said the gut nervous system is like a mediator between the central nervous system and the immune system. The gut nervous system acts as the first responder when the immune system encounters bacteria, parasites, viruses or toxins in food.
David Sigalet from the University of Calgary then discussed how a hormone called GLP-2 helps control gut function. This hormone is produced when cells in the gut sense undigested nutrients. The hormone then induces the development of cells that digest the nutrients. Sigalet said treatment with GLP-2 has been shown to help human babies with gut development problems. Perhaps, he said, GLP-2 is also crucial in livestock species.
To round out the symposium, University of Liverpool research Soraya Shirazi-Beechey focused on the response of the gut nervous system and endocrine system to different concentrations of glucose in the gut. Shirazi-Beechey presented data from young pigs showing that sensors called sweet taste receptors sense glucose and lead to the release of GLP-2. This study confirms research in rodents and emphasizes the complex relationship between food, the gut and the gut nervous system.
“Further elucidation of the interplay between various components of the gut, and how they react to signals from the diet, could facilitate the discovery of novel feed additives and the development of sustainable technologies for improving production efficiency,” wrote Bravo.
Understanding the gut nervous system could keep livestock and humans healthier. This research could also help feed the world. According to Bravo, improving gut function could boost production of food animals. With more healthy, efficient animals, producers could raise more food for more people.
This symposium was sponsored, in part, by Pancosma and the European Federation of Animal Science (EAAP)with publication sponsored by the Journal of Animal Science and the American Society of Animal Science. Abstracts and papers featured in this article can be read at http://journalofanimalscience.org/
David Bravo, Pancosma
Madeline McCurry-Schmidt, American Society of Animal Science