Cholecystokinin: What It Is, And Effects Of This Hormone And Neurotransmitter
Cholecystokinin (CCK) is a hormone secreted in the intestine and is activated in response to the ingestion of certain foods. It intervenes in processes such as digestion and appetite, generating a feeling of satiety that helps us regulate appetite.
In this article we explain in more detail what this hormone is and what functions it performs, how the satiety effect is produced and what the most recent research says about its possible role in preventing cognitive decline.
Cholecystokinin is produced in the small intestine, specifically in the duodenum and jejunum, and causes contraction of the gallbladder and pancreatic secretion. This hormone is also considered a neurotransmitter that is released in the nervous system especially in the hypothalamus.
This hormone belongs to the group of kinins, which are formed from globulins (a group of water-soluble proteins present in animals and plants) by proteolytic enzymatic action. Proteolysis involves the degradation of proteins, either by specific enzymes or through intracellular degradation.
The secretion or production of cholecystokinin It depends on factors such as the presence of some nutrients from the food stored in the intestine mainly fats and proteins (fatty acids and amino acids).
Features
Cholecystokinin fulfills several functions, both in its role as a gastrointestinal hormone and in its action as a neurotransmitter of the nervous system.
As a gastrointestinal hormone
Cholecystokinin, along with gastrin and secretin, constitutes one of the main hormones secreted at the gastrointestinal level. It is known that CCK secretion and its effects on gastric motility depend on ingested fats specifically the length of the fatty acid chain.
Cholecystokinin has also been found in the brain (mainly in the cortex, although also in other areas such as the retina, hippocampus, hypothalamus and spinal cord) and plays a role as a neurotransmitter or neuromodulator, acting on the neurons of the periaqueductal gray matter, which are related to perception. pain, and on the neurons of the medial hypothalamus, which are responsible for controlling food intake.
CCK levels usually rise towards the end of the meal, triggering satiety mechanisms. The presence of CCK in the amygdala and in some areas of the cerebral cortex has led researchers to suggest that this hormone could have a role related to emotions.
It has also been discovered that cholecystokinin has an anxiogenic (anxiety-causing) function in the brain, since in various studies it has been proven that injecting agonists into one of the CCK receptors produces autonomic and behavioral changes associated with sensations such as fear and anxiety, while antagonistic substances cause the opposite.
The CCK, in addition, seems to interact in synapses with another neurotransmitter, dopamine especially in the nigrostriatal fibers that innervate the striatum and the nucleus accumbens, a brain structure involved in reward systems and responsible for integrating motivational information with emotions and motor actions.
CCK and the satiety effect
Cholecystokinin (CCK) It is the best-studied satiety-inducing peptide Let’s see, below, how this effect is produced.
CCK is secreted by the I cells of the mucosa of the duodenum and jejunum in response to the presence of partially digested fats and carbohydrates from the stomach.
This hormone, as we have mentioned previously, causes contraction of the gallbladder, release of pancreatic enzymes, inhibition of motility and gastric emptying thus reducing the size of the food ingested.
The secretion of cholecystokinin is activated by the presence of products derived from the degradation of fats, peptides, amino acids and, to a lesser extent, dietary carbohydrates; and is inhibited by the intestinal concentration of pancreatic proteases (trypsin and chymotrypsin) and bile, after ingestion of food.
CCK causes contraction of the pylorus (the lower opening of the stomach that communicates with the small intestine), generating gastric distension that activates vagal afferents that relay to the nucleus of the solitary tract to, finally, stimulate the satiety center; a satiating effect that lasts approximately 90 minutes.
Recent research
Recent research carried out by scientists at the University of Iowa in the United States suggests that a high level of cholecystokinin could decrease a person’s chance of developing Alzheimer’s disease
The researchers carried out a study with 287 subjects and chose this hormone, which acts as a neurotransmitter in the brain, due to its high expression in the formation of a cognitive process such as memory.
Their objective was to detect whether there is a relationship between cholecystokinin levels and memory, and the state of gray matter in the hippocampus and other related brain areas.
At the same time, neuroscientists studied tau proteins (whose accumulation is linked to the development of Alzheimer’s disease), with the goal of seeing how they might interact with cholecystokinin and memory.
The results of the study concluded that, as tau protein levels increased, a similarly high level of cholecystokinin was no longer related to less memory impairment
This research highlights the importance of studying the nutritional aspect of diets, as well as its relationship with mental health and its implication in the prevention of cognitive deterioration and neurodegenerative disorders such as Alzheimer’s disease.
