Adipose Tissue as an Endocrine Organ

Abstract

Adipose tissue is a complex, essential, and highly active metabolic and endocrine organ. Besides adipocytes, adipose tissue contains connective tissue matrix, nerve tissue, stromovascular cells, and immune cells. Together these components function as an integrated unit. Adipose tissue not only responds to afferent signals from traditional hormone systems and the central nervous system but also expresses and secretes factors with important endocrine functions. These factors include leptin, other cytokines, adiponectin, complement components, plasminogen activator inhibitor-1, proteins of the renin-angiotensin system, and resistin. Adipose tissue is also a major site for metabolism of sex steroids and glucocorticoids. The important endocrine function of adipose tissue is emphasized by the adverse metabolic consequences of both adipose tissue excess and deficiency. A better understanding of the endocrine function of adipose tissue will likely lead to more rational therapy for these increasingly prevalent disorders. This review presents an overview of the endocrine functions of adipose tissue.

Mechanisms by which diabetes increases cardiovascular disease

“…These defects seem to be closely related to increased body fat. Indeed, visceral abdominal fat has important endocrine functions, leading to increased serum levels of TNF-α, interleukin-6, plasminogen activator inhibitor (PAI-)1, and reduced expression of adiponectin [46]. These changes in adipokines -these are cytokines produced by adipose tissue -could also lead to reduced insulin signaling and activation of cytokines, transcription factors such as NFκB and activated mitogen kinases such as JNK, both also leading to insulin resistance.…”

Association Between Adiposity and Lean Mass With Long‐Term Cardiovascular Events in Patients With Coronary Artery Disease: No Paradox

“…Obesity is associated with an increased risk of coronary artery disease (CAD), heart failure, hypertension, atrial fibrillation, and many other cardiovascular conditions 1. Adipose tissue is not a simple storehouse for fat, but rather an endocrine organ that is capable of synthesizing and releasing a variety of molecules, such as leptin, adiponectin, tumor necrosis factor‐α, interleukin‐6, and many others, that play a central role in the pathophysiological features of inflammation and CAD 2. However, numerous publications have demonstrated the existence of an “obesity paradox,” where overweight and obese people with CAD or heart failure have a better prognosis than normal weight people with similar conditions and cardiovascular risk factors 3.…”

Angiotensin II: a hormone that affects lipid metabolism in adipose tissue

“…Part of this association may be explained by adipose tissue products that exert autocrine, paracrine and/ or endocrine effects that may affect metabolism. [1][2][3] A functional renin-angiotensin system (RAS) is present in human adipose tissue, [4][5][6] and local generation of angiotensin II (Ang II), the effector molecule of the RAS, by human (pre)adipocytes has been demonstrated. 7 The adipose tissue RAS may be involved in obesity-related disorders, such as insulin resistance, 8,9 possibly through an effect on adipocyte differentiation.…”