What hormone stimulates the secretion of gastric juice in response to food?

Gastrin is the hormone that specifically stimulates the secretion of gastric juice in response to the presence of food in the stomach. When food enters the stomach, it stretches the gastric walls, triggering G cells in the gastric mucosa to release gastrin into the bloodstream. This hormone then promotes the secretion of gastric acid from parietal cells and pepsinogen from chief cells, both of which are essential for the digestion of proteins in the food.

Gastrin's role also includes increasing gastric motility, which helps mix the food with gastric juices for better digestion. This process is critical for the proper breakdown of food and absorption of nutrients. While other hormones like insulin are involved in metabolic processes and regulation of blood sugar levels, they do not directly stimulate gastric juice secretion. Serotonin is primarily involved in regulating mood and intestinal motility, and histamine, while it has a role in gastric acid secretion, primarily acts as a mediator in the action of gastrin rather than being the primary stimulator itself. Thus, gastrin stands out as the key hormone responsible for initiating gastric juice secretion in response to food intake.