Gut endocrine secretions and their relevance to satiety

The three major regions of the gastrointestinal tract (stomach, upper small intestine, ileum/colon) are each the source of factors influencing food intake. These can enhance appetite or, conversely, inhibit it. The active factors include hormones, lipid mediators, nutrients and gastric distension. Vagal afferent neurons mediate the effects of some gut signals on the brain, but other gut hormones also act directly on the brain in areas where the blood-brain barrier can be penetrated. Many different interactions between these factors are now emerging. Collectively, this system presents an array of new potential targets in seeking to modify energy intake.