What type of peptides stimulate G cells to secrete gastrin?

Dipeptides and tripeptides are the types of peptides that stimulate G cells to secrete gastrin. G cells, located in the stomach's antrum, respond primarily to the presence of these short chains of amino acids, triggering the release of gastrin, a hormone that plays a crucial role in the digestive process.

When food enters the stomach, proteins are broken down into various peptide fragments, often including dipeptides and tripeptides. These fragments bind to specific receptors on G cells, thereby promoting gastrin secretion. The released gastrin, in turn, stimulates the parietal cells to secrete gastric acid, which is essential for protein digestion and also helps in controlling the growth of bacteria in the stomach.

Other forms of peptides, such as single amino acids or only longer polypeptides, may not effectively stimulate gastrin secretion in the same manner. The specificity of the interaction between G cells and dipeptides and tripeptides highlights the complexity and regulation of gastrointestinal hormones in response to varying forms of dietary proteins.