Thermogenesis

There has been considerable focus on the development of drugs that lead to a reduction in the total amount of adipose tissue. These include agents targeted at limiting fat absorption, the inhibition of appetite, and the stimulation of energy expenditure (thermogenesis)-or a combination thereof. The best example of drugs,... 

Functionally, the onset of fever is mediated by an increase in metabolic heat production (thermogenesis) and cutaneous vasocontriction (to reduce heat loss from the skin), and by cessation of sweating, if present. The... 

Brain structure below the thalamus and main portion of the ventral region of the diencephalon, controlling homeostatic and nonhomeostatic basic body and brain functions, including circadian and feeding rhythms, energy metabolism, thermogenesis, sympathoadrenal, and neuroendocrine outflow (secretion of hormones by the pituitary gland), behavioral state and memory functions. 

PPAR5 Ubiquitous Potent TG- and LDL-C-lowering and potent HDL-C-raising increased oxidative disposal of fatty acids in adipose and skeletal muscle thermogenesis weight loss Fatty acids, eicosanoids (fatty acids derived from VLDL particles ) GW501516 currently in Phase II clinical trials Dyslipidemia, obesity atherosclerosis ... 

Brown adipose tissue is the site of nonshivering thermogenesis. It is found in hibernating and newborn animals and is present in small quantity in humans. Thermogenesis results from the presence of an uncouphng protein, thermogenin, in the inner mitochondrial membrane. 

Body temperature by regulating metabolic thermogenesis (e.g., shivering) and behaviors that cause an individual to seek a warmer or cooler environment... 

Beta-1, beta-2, and beta-3 adrenergic receptors are G-protein-coupled receptors. Beta-1 and beta-2 receptors mediate the positive inotropic, chronotropic, and dro-motropic effects of the endogenous catecholamines epinephrine and norepinephrine. The beta-3 subtype seems to play a role in regulating thermogenesis and lipid mobilization in brown and white adipose tissue. Several coding and promoter polymorphisms of these receptors have been identified. Clinical studies in asthma... 

However, for a quantitative kinetic analysis of the calorimetric data, corrections must be applied, because the thermal inertia of the calorimeter, which cannot be completely removed, causes in many cases the blurring of the thermogenesis. Several methods have been proposed, with different levels of sophistication. 

Calories consumed in food are used by the body as fuel. The body s use of calories as its source of energy is called thermogenesis. Literally, thermogenesis means the production of heat because when people burn calories, heat is produced. The body needs a constant supply of fuel to maintain normal functions that people don t usually think about, like breathing. 

The major types of adipose tissue are (1) white adipose tissue, which manufactures, stores, and releases lipid and (2) brown adipose tissue, which dissipates energy via uncoupled mitochondrial respiration. Obesity research includes evaluation of the activity of adrenergic receptors and their effect on adipose tissue with respect to energy storage and expenditure or thermogenesis. 

Khat produces sympathomimetic effects, increasing heart rate and blood pressure. When khat is chewed, the increases are gradual, maximizing at about 2 hours and lasting for 4 hours. However, tolerance develops to blood pressure and heart rate effects in habitual users. Mydriasis and increases in respiration also occur. Cathinone induces thermogenesis in brown adipose tissue, which is mediated by jS-adrenergic receptors (Tariq et al. 1989). 

Tariot PN, Cohen RM, Welkowitz JA, Sunderland T, Newhouse PA, Murphy DL, Tariq M, Islam MW, al-Meshal lA, el-Feraly FS, Ageel AM. (1989). Comparative study of cathinone and amphetamine on brown adipose thermogenesis. Life Sci. 44(14) 951-55. 

Thermic effect of food It has long been observed that eating a meal increases energy expenditure, a phenomenon also known as diet-induced thermogenesis or specific dynamic action. The increase depends on the type and quantity of food consumed. As an example, the effect of a carbohydrate-rich meal on the oxygen consumption of volunteers before and after exercise is shown in Figure 2.5. 

To produce heat so as to maintain body temperature (known as non-shivering thermogenesis) (Chapter 9). 

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