Leptin (from Greek λεπτός leptos, "thin" or "light" or "small") is a protein hormone predominantly made by adipose cells and its primary role is likely to regulate long-term energy balance.
As one of the major signals of energy status, leptin levels influence appetite, satiety, and motivated behaviors oriented towards the maintenance of energy reserves (e.g., feeding, foraging behaviors).
The amount of circulating leptin correlates with the amount of energy reserves, mainly triglycerides stored in adipose tissue. High leptin levels are interpreted by the brain that energy reserves are high, whereas low leptin levels indicate that energy reserves are low, in the process adapting the organism to starvation through a variety of metabolic, endocrine, neurobiochemical, and behavioral changes.
Leptin is coded for by the LEP gene. Leptin receptors are expressed by a variety of brain and peripheral cell types. These include cell receptors in the arcuate and ventromedial nuclei, as well as other parts of the hypothalamus and dopaminergic neurons of the ventral tegmental area, consequently mediating feeding.
Although regulation of fat stores is deemed to be the primary function of leptin, it also plays a role in other physiological processes, as evidenced by its many sites of synthesis other than fat cells, and the many cell types beyond hypothalamic cells that have leptin receptors. Many of these additional functions are yet to be fully defined.
In obesity, a decreased sensitivity to leptin occurs (similar to insulin resistance in type 2 diabetes), resulting in an inability to detect satiety despite high energy stores and high levels of leptin. A synonym for LEP is OB (for obese).
Leptin receptor and Energy expenditure
Predominantly, the "energy expenditure hormone" leptin is made by adipose cells, and is thus labeled fat cell-specific. In the context of its effects, the short describing words central, direct and primary are not used interchangeably.
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Le but est de connaitre et comprendre le fonctionnement des systèmes cardiovasculaire, urinaire, respiratoire, digestif, ainsi que du métabolisme de base et sa régulation afin de déveloper une réflect
Ce cours présente les principes fondamentaux à l'œuvre dans les organismes vivants. Autant que possible, l'accent est mis sur les contributions de l'Informatique aux progrès des Sciences de la Vie.
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Covers carbohydrate, lipid, and protein metabolism, insulin-receptor interaction, fat storage, and blood glucose control.
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