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Exploring ghrelin: How does this mysterious hormone control our appetite?
In our daily lives, there is always a force that drives us to feel hungry, and that is the famous "hunger hormone" ghrelin. This mysterious hormone is produced primarily by enteroendocrine cells in our gastrointestinal tract, especially in the stomach. The secretion of ghrelin is closely related to our eating habits. Its blood concentration usually reaches a peak before a meal and decreases rapidly after a meal.
Ghrelin is considered not only a regulator of food intake, but also involved in the regulation of energy balance and endocrine function.
According to research, ghrelin can increase gastric motility and stimulate the secretion of gastric acid, which helps the body prepare for eating. Not only that, ghrelin can also affect specific neurons in the brain, such as the fasting sensor in the forebrain, thereby increasing appetite.
History and nomenclature of ghrelin
The discovery of this hormone dates back to 1999, when scientists successfully identified the receptor for ghrelin - the growth hormone secretion-stimulating hormone type 1A receptor (GHS-R1A). The name derives from ghrelin's role in promoting the release of growth hormone, closely related to its original meaning, "growth". This background provides us with a deeper understanding of this hormone.
Ghrelin gene, crystal structure and transcripts
The mRNA produced by the GHRL gene has four exons, which are then cut to produce pre-proghrelin consisting of 117 amino acids and active ghrelin. During this process, ghrelin must be linked to octanoic acid to become its biologically active form. All of this happens in the stomach and pancreas, and the inactive form of ghrelin, non-octanoate, is unable to activate the GHS-R receptors but can still perform other effects.
Function and mechanism of action of ghrelin
Ghrelin plays an important role in the regulation of energy homeostasis, influencing our body weight by modulating hunger signals and energy expenditure. When the hormone ghrelin is released into the blood, our appetite increases rapidly. Although ghrelin promotes motivation to eat, it does not increase the amount of food consumed at each meal.
Ghrelin levels peak before meals and decrease after meals, indicating a close relationship with food intake.
Studies have shown that ghrelin injections can lead to increased food intake in animals, making ghrelin not only an appetite stimulant but also an important regulator of energy balance. Ghrelin not only plays a role in energy control, but also promotes the expression of rewarding behaviors by triggering neurons in the brain's reward center. This makes us wonder, in the process of seeking pleasure in eating, will ghrelin restrict our behavior or liberate our desires?
Ghrelin and the functions of various physiological systems
Ghrelin is involved in a wide range of physiological mechanisms, from regulating blood sugar metabolism to affecting sleep patterns. Preliminary studies have shown that ghrelin may be closely related to the regulation of sleep, and much evidence has confirmed that lack of sleep can affect the secretion of ghrelin.
In terms of the reproductive system, the secretion of ghrelin can inhibit the release of gonadotropin, which may affect fertility. In the cardiovascular system, ghrelin has shown potential to protect the heart and is closely linked to inflammatory responses.
Clinical significance of ghrelin
The role of ghrelin in disease also deserves attention. For example, in patients who undergo gastric bypass surgery, ghrelin levels are significantly reduced, which may aid in weight management. Conversely, in some conditions caused by hunger and emaciation, such as anorexia, ghrelin levels are elevated, possibly reflecting the body's need for food intake. This change in ghrelin triggers a deeper thought: Can changes in ghrelin under different health conditions be the key to our understanding of eating behavior?
Ghrelin is not only an important hormone for regulating appetite, but also a key player in energy metabolism, sleep quality and cardiovascular health. As scientific research further explores the potential of this mysterious hormone, it may be possible to develop ghrelin-based disease treatments in the future. However, with this knowledge in hand, should we rethink the relationship between our eating habits and our body's needs?
