The endocrine function of adipose tissue: an update

Abstract

SummaryAdipose tissue secretes bioactive peptides, termed 'adipokines' , which act locally and distally through autocrine, paracrine and endocrine effects. In obesity, increased production of most adipokines impacts on multiple functions such as appetite and energy balance, immunity, insulin sensitivity, angiogenesis, blood pressure, lipid metabolism and haemostasis, all of which are linked with cardiovascular disease. Enhanced activity of the tumour necrosis factor and interleukin 6 are involved in the development of obesity-related insulin resistance. Angiotensinogen has been implicated in hypertension and plasminogen activating inhibitor-1 (PAI-1) in impaired fibrinolysis. Other adipokines like adiponectin and leptin, at least in physiological concentrations, are insulin sparing as they stimulate beta oxidation of fatty acids in skeletal muscle. The role of resistin is less understood. It is implicated in insulin resistance in rats, but probably not in humans. Reducing adipose tissue mass, through weight loss in association with exercise, can lower TNF-α and IL-6 levels and increase adiponectin concentrations, whereas drugs such as thiazolinediones increase endogenous adiponectin production. In-depth understanding of the pathophysiology and molecular actions of adipokines may, in the coming years, lead to effective therapeutic strategies designed to protect against atherosclerosis in obese patients

Contrasting cellularity on fat deposition in the subcutaneous adipose tissue and longissimus lumborum muscle from lean and fat pigs under dietary protein reduction

“…Sequestration of lipids into the adipose tissue is a critical process in the control of glucose homeostasis (Le Lay and Dugail, 2009). Indeed, leptin has the ability to reduce intracellular lipid levels in the skeletal muscle, thereby improving insulin sensitivity (Ronti et al, 2006). Following on the results found for insulin, the HOMA-IR index was, as one would expect, affected by genotype with higher values in the fat pigs when compared with the lean pigs, although without evidence for insulin resistance.…”

Fat poetry: a kingdom for PPARγ

“…This role will not be discussed here as it has been reviewed recently [115]. Similarly, the role of adipokine in the interaction between adipose tissue and immunity has been summarized recently and will not be presented here [34,77].…”

“…Although several adipokines involved in energy homeostasis were discovered in recent years, the so far most studied ones are leptin, adiponectin, resistin, angiopoietin-like protein 4, and preadipocyte factor 1, on which this section will concentrate. In addition, information on other adipokines is given in Table 1 and Figure 4, or can be found in several review articles [26,[34][35][36][37][38].…”

A 3-year Mediterranean-style dietary intervention may modulate the association between adiponectin gene variants and body weight change

“…Adipose tissue, traditionally considered as an energy storage depot, has demonstrated to be an active endocrine organ secreting numerous proteins that play important metabolic roles [1]. Adiponectin is abundantly expressed in adipose tissue [2], and can have antiatherogenic, antiinflammatory, and insulin-sensitizing properties [3].…”