Hypothalamic control
Eating behavior is formed in the hypothalamic nuclei, which receive impulses from peripheral nerve endings.
- Appetite stimulants: GABA, dopamine, β-endorphin, enkephalins.
- Appetite inhibitors: serotonin, norepinephrine, cholecystokinin, somatostatin.
Of particular importance is neuropeptide Y, which stimulates the feeling of hunger. Normally, leptin suppresses its synthesis, but when hypothalamic sensitivity to leptin decreases, neuropeptide Y is disinhibited, which triggers overeating.
Key adipokines
Adipose tissue is not just an energy depot, but an active endocrine organ:
- Leptin: synthesized by adipocytes, reduces appetite and increases energy expenditure. Its level is proportional to fat mass.
- Adiponectin: increases tissue sensitivity to insulin. Its concentration drops in obesity.
- Resistin: an insulin antagonist that inhibits glucose uptake by cells.
- Ghrelin: produced in the stomach and intestines, it is a potent hunger stimulant.
Mechanisms of obesity development
Obesity is often associated with impaired regulatory loops:
- Leptin deficiency: absolute or relative leptin deficiency leads to a constant feeling of hunger.
- Centrogenic mechanism: psychogenic factors where eating becomes a way to gain pleasure by activating behavioral reinforcement systems.
- Metabolic shifts: adipokine imbalance in children and adults potentiates the development of insulin resistance and disrupts free fatty acid metabolism.
Briefly: answers to topical questions
In which specific hypothalamic nuclei are the hunger and satiety centers localized?
The satiety center is localized in neurons of the ventromedial hypothalamic nucleus. The specific nuclei forming the hunger center are not specified in the provided materials. In general, impulses from peripheral nerve endings are integrated in the hypothalamic nuclei, leading to the production of mediators—appetite stimulants (GABA, dopamine) or inhibitors (serotonin, cholecystokinin).
Which biologically active substances are classified as adipokines?
The main adipokines include the following biologically active substances:
- Leptin — reduces appetite and increases the body's energy expenditure;
- Adiponectin — correlates with tissue sensitivity to insulin;
- Resistin — is a cysteine-rich protein insulin antagonist;
- Ghrelin — regulates energy balance and directly stimulates appetite.
Which gastrointestinal hormones, besides ghrelin and cholecystokinin, are involved in the formation of the feeling of satiety?
The provided sources do not cite a confirmed list of GI hormones specifically involved in forming the feeling of satiety, other than cholecystokinin. The following is confirmed:
- cholecystokinin is classified as an appetite inhibitor and forms the feeling of satiety;
- somatostatin is also indicated as an appetite inhibitor that forms the feeling of satiety;
- incretins — GLP-1 and glucose-dependent insulinotropic polypeptide — are GI hormones secreted by the small intestine in response to food intake and potentiate glucose-stimulated insulin secretion, but their involvement in forming satiety is not indicated in the sources.
What are the main pathogenetic mechanisms of obesity development?
The main pathogenetic mechanisms of obesity development include the following variants:
- Centrogenic mechanism — associated with mental disorders and a constant desire to eat;
- Leptin mechanism — occurs due to absolute or relative leptin deficiency;
- Insulin mechanism — caused by an increase in the number or hypersensitization of insulin receptors, which activates lipogenesis;
- Hypothyroid mechanism — develops due to insufficient thyroid hormone action, suppressing metabolism and lipolysis.
Leptin STOPS SATIETY (reduces appetite), Ghrelin GRABS FOOD (stimulates hunger).
Class and exam questions
Why doesn't leptin help lose weight in obesity?
In obesity, a decrease in hypothalamic sensitivity to leptin often develops. As a result, the "satiety signal" is not perceived, and the synthesis of neuropeptide Y, which stimulates hunger, is not suppressed.
What is the difference between the actions of leptin and resistin?
Leptin helps reduce appetite and energy expenditure, whereas resistin is an insulin antagonist and prevents normal glucose uptake by cells.
How do ghrelin levels change throughout the day?
Ghrelin levels are higher on an empty stomach, which stimulates food-seeking behavior. After eating, its concentration decreases, contributing to the formation of a feeling of satiety.
What else to study on this topic
- The pulsatile nature of leptin secretion and its nocturnal peak.
- The role of leptin as a growth factor (angiogenesis, cell proliferation).
- The effect of adiponectin on the development of diabetes mellitus.
- Genetic aspects of ghrelin gene mutations.
- The relationship between adipocyte differentiation and resistin synthesis.
Master the entire topic in the "Pathophysiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Appetite Regulation and Adipokines" and 4,913 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 135 video lessons on the subject
Other topics in the section "Chapter 10. Disorders of Lipid Metabolism"
Free video lessons: pathophysiologyShort lessons with lecture notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.