BIOL–15 Extra Credit
Bugs, Guts, and Brains Seminar Summary
During the seminar “Bugs, guts and brains: How gut microbiota shapes your mind and body” on November 7, Physiologist from UC Davis, Dr. Helen Raybould discussed how gut microbes in humans and animals affects neurophysiology based primarily on the foods we eat and the genes expressed in the gut. There is an intersection between micro and host physiology that affects the overall health and behavior of the host. To understand this, the neural pathways by which macronutrients are detected in the intestine were discussed.
The gut’s primary function is the intake, digestion and absorption of nutrients and water. It is of high importance, as it is the largest immune and endocrine organ in the body. It generates signals when eating to digest the food, and in turn the nutrients stimulates hormone release, causing activation of neurons in the brain to achieve regulation of food intake and homeostasis. The gut and lumen is the biggest interface between the inside of the body and the outside world.
The gastrointestinal tract is considered to be a sensory organ. Endocrine cells respond to the gut and transmit information to the body. The epithelial layer lines the gut, and the hormones and peptides are released from the basilolateral foot of the cell. Chemosensing cells respond to all nutrients, and make up the concept that the gut is a sensory organ. Microvilli have contact with the lumen and do the sensing. The introduction of glucose in the body stimulates the release of 5HT (luminal chemosensors) enteroendocrine cells. Endocrine cells have to be mediated through the bloodstream. They act as true hormones in that they activate neurons, in turn activating the gut, and ultimately send the information to the brain.
Vagal afferent neurons transmit activities of the gut lumen to the central nervous system. Pancreatic secretions and are fed forward to the hypothalamus (related to behavior), resulting