Chapter Category: Cell Metabolism
From the book Adipose Tissue
White Adipose Tissue as a Secretory and Endocrine Organ:Leptin and Other Secreted Proteins
Paul Trayhurn, Nigel Hoggard, D. Vernon Rayner
We are currently undergoing a revolution in our perspectives on the physiological role of white adipose tissue (WAT). Traditionally, white fat has been viewed primarily as a longterm energy storage organ. The deposition of triacylglycerol with twice the energy density of carbohydrate and with little associated water (in the region of 15%) provides a concentrated and highly efficient energy reserve. The central role of WAT in the storage of lipid has resulted in lipogenesis and lipolysis being viewed as the major metabolic processes associated with the organ, and much is known about the nature and regulation of these pathways. A second role widely attributed to WAT, at least for the subcutaneous deposits, is that of thermal insulation and in the case of the blubber of aquatic mammals such as whales the tissue may even have a mechanical role. Brown fat, the other form of adipose tissue, has the generation of heat, both thermoregulatory and in relation to the regulation of energy balance, as its primary function (see Chapters 4 and 5 by Klaus).
\r\nThe overall picture of the central functions of WAT has changed radically in recent years, with white fat now being viewed as a major endocrine organ, secreting both a critical hormone and a number of protein factors which play either a local or systemic role. By virtue of the secretion of these diverse factors it is now evident that WAT is actively involved in a range of physiological processes, including the regulation of energy balance and the control of blood pressure and of vascular homeostasis. In this chapter we present an overview of the endocrine and secretory role of WAT. The protein secreted by white fat which has been principally responsible for altering our views on the functional role of the tissue is the cytokinelike hormone leptin and this factor is therefore the principal focus of the chapter.
\r\n- ISBN: 1-58706-040-X
- Publication date: September 1, 2001
- Series: Intelligence Unit
Adipose Tissue
Edited by: Paul Trayhurn, Nigel Hoggard, D. Vernon Rayner
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