Secretin belongs to the glucagon family. This protein is an endocrine hormone and its major site of production is the endocrine S cells located in the proximal small intestinal mucosa. The release of active secretin is stimulated by either fatty acids or an acidic pH in the duodenum. This hormone stimulates the secretion of bicarbonate-rich pancreatic fluids and has also been shown to regulate the growth and development of the stomach, small intestine, and pancreas. Secretin deficiency has been implicated in autistic syndrome, suggesting that the hormone could have a neuroendocrine function in addition to its role in digestion.
