Inhibition of gastric secretions is brought about by

The correct option is GIP.

Gastric secretion is a highly regulated physiological process controlled by both hormonal and neural mechanisms to ensure optimal digestion. The regulation involves both stimulatory signals (which promote secretion) and inhibitory signals (which suppress secretion when digestion in the stomach is complete or when the duodenum needs time to process food).

Let's break down the role of the gastrointestinal hormones listed in the options to understand why GIP is responsible for inhibiting gastric secretions:

1. Gastric Inhibitory Peptide (GIP):
GIP (also known as glucose-dependent insulinotropic polypeptide) is a hormone synthesized and secreted by the K cells located in the mucosa of the duodenum and jejunum. It is released primarily in response to the presence of fat, proteins, and glucose in the duodenum. One of its primary physiological actions is the feedback inhibition of gastric acid secretion and gastric motility. By slowing down stomach emptying and reducing acid production, GIP protects the duodenum from excessive acidity and coordinates the transit of chyme.

2. Gastrin:
Gastrin is a hormone produced by the G cells of the gastric antrum and duodenum. Unlike GIP, gastrin is a primary stimulator of gastric acid secretion. It acts on parietal cells to trigger the release of hydrochloric acid (HCl).

3. Cholecystokinin (CCK):
CCK is secreted by the I cells of the duodenum and jejunum, mainly in response to fatty acids and amino acids. Its main functions are stimulating gallbladder contraction (to release bile) and pancreatic enzyme secretion, rather than serving as the primary direct inhibitor of gastric acid secretion.

4. Pancreozymin:
Pancreozymin is another name for Cholecystokinin (specifically referring to its action of stimulating the secretion of pancreatic enzymes). Thus, its primary role is digestive enzyme secretion from the pancreas.

Therefore, among the given choices, the hormone specifically known for bringing about the inhibition of gastric secretions is Gastric Inhibitory Peptide (GIP).