The concept of cholecystokinin

Cholecystokinin(CCK) is a polypeptide consisting of 33 amino acids isolated from the small intestine extract. To stimulate the gallbladder to shrink and excite the role of pancreatic enzyme secretion.

Overview of Cholecystokinin

Cholecystokinin was certified and purified in 1928 and in 1943. There are many chemical structures of natural cholecystokinin, CCK-33, CCK-39, CCK-58, and a 8-peptide cholecystokinin isolated from goat and human cerebellum. Cholecystokinin-containing cells are present in the mammalian duodenum and jejunum mucosa, and the cells are identical to human intestinal I cells. In 1978 it was found that cholecystokinin is also present in the central nervous system, and the content is greater than the small intestine content, exists in the cortex frontal lobe, cortical pear, caudate nucleus, hippocampus, thalamus, hypothalamus, cerebellum and brain. Cholecystokinin is rapidly degraded in blood and has a half-life of about 3 minutes. With a variety of biological effects, mainly to stimulate the secretion and synthesis of pancreatic enzymes, enhanced pancreatate bicarbonate secretion, stimulate gallbladder contraction and Odyssey sphincter relaxation, but also excitement of liver and gallbladder secretion, regulating the small intestine, colon movement, but also as satiety factor to adjust the feeding.

Introduction of cholecystokinin

Cholecystokinin published in the January 2004 issue of the United States, "AJP-Gastrointestinal and Liver Physiology" (American Journal of Gastrointestinal and Liver Physiology) on a study shows that cholecystokinin in the coordination of gastrointestinal activities play a role in eating An important medium for mass control.

Dr. John Moran TH of Johns Hopkins School of Medicine points out that when eating, the intake of nutrients accumulates in the stomach and gradually enters the small intestine. Intake of nutrients can cause a series of physiological reactions, thereby promoting the overall digestion process.

Researchers pointed out that in the course of eating, will release a variety of neuropeptides and neurotransmitters, and further coordination of gastrointestinal secretion and movement, and ultimately lead to satiety and stop eating. Which cholecystokinin is a brain/intestinal hormone, food intake to promote its secretion.

Dr. Moran says cholecystokinins play a role in regulating coordination of gastrointestinal activity and are an important medium for food intake control.

The explanation of the term of cholecystokinin

Cholecystokinin (CCK) is a peptide hormone released by small intestinal mucosal I cells. Its main role is to promote pancreatic acinar secretion of a variety of digestive enzymes, promote gallbladder contraction, discharge bile, water and HCO3-induced secretion is weak. Cholecystokinin can also act on vagal afferent fibers and stimulate pancreatic secretion by vagal-vagal reflex. Cholecystokinin acts on the pancreas by Ca2 + activation by activating the phosphatidyl alcohol system. Cholecystokinin and secretin have synergistic effect.

After eating, the protein hydrolyzate can stimulate the small intestine mucosa to release a cholecystokinin to stimulate the small intestinal mucosa I cells secrete cholecystokinin. The factors that cause cholecystokinin secretion from strong to weak are: protein decomposition products, fatty acid salts, HCl, fat, sugar has no effect. In addition, insulin can enhance cholecystokinin amylase secretion effect.

Small intestine mucosa secretion of cholecystokinin is very sensitive to trypsin, trypsin can inhibit the cholecystokinin release peptide, so the cholecystokinin release peptide, causing cholecystokinin release and pancreatic enzyme secretion increased, the trypsin will So that the loss of activity, and thus inhibit the inhibition of cholecystokinin and trypsin further secretion. The physiological significance of feedback regulation of pancreatic enzyme secretion is to prevent excessive secretion of trypsin. I summarize the effects of gastrin, secretin, cholecystokinin and digestion in the following table:

Reduce the secretion of trypsin, that is to say in the diet to reduce the consumption of cattle, sheep, pig offal and some dried fruits and vegetables. This is why people who like to eat animal offal and dried fruit eat more and more want to eat.

The principle of cholecystokinin

Cholecystokinin through the effects of food and the body of the various enzymes in the complex, to help break down the decomposition of protein products, fatty acid salts, HCl and other stimuli secretion of cholecystokinin to stimulate the inside of the hypothalamus, resulting in a large number of satiety signals The

Cholecystokinin is easily degraded in blood to lose its activity with a half-life of about 3 minutes. At this time need to inhibit the secretion of trypsin, and sustained decomposition of cholecystokinin factor to stimulate the secretion of cholecystokinin, so that the abdominal signal continued to stimulate the thalamus. And acts on the feeding center nerve inhibition of appetite.

Medical prospect of cholecystokinin

Cholecystokinin as an important brain-gut peptide hormone, the digestive tract has a wide range of important regulatory role. Cholecystokinin content changes and changes in receptor sensitivity, often leading to the occurrence of gastrointestinal motility disease. In recent years, the physiological role of cholecystokinin in gastrointestinal motility and its pathologic effect in gastrointestinal motility have been paid attention to, and a lot of studies have been carried out to elucidate the basic physiological and pathological effects of cholecystokinin. Cholecystokinin analogues and receptor antagonists have been used in clinical clinics. The physiological effects of cholecystokinin are affected by various factors of neurohumoral fluid, the mechanism is more complex. In the present study, some human experiments and animal experiments, different animal species experiments, the overall and in vitro experiments there are differences and contradictions, and more to speculate to explain the reasons, can not form a unified theory. The physiological mechanism and mechanism of cholecystokinin are not fully understood. For further study of cholecystokinin and its receptors is conducive to further clarification of digestive tract physiology, is conducive to the diagnosis and treatment of gastrointestinal motility disease, the development of gastrointestinal motility of new drugs is also important.