Regional differences of insulin action in adipose tissue: insights from in vivo and in vitro studies

Abstract

Adipose tissue is now recognized to have a multitude of functions that are of importance in the regulation of energy balance and substrate metabolism. Different hormones, in particular insulin and catecholamines, govern the storage and utilization of energy in the triglyceride depots. In addition, adipocytes produce several different substances with endocrine or paracrine functions, which regulate the overall energetic homeostasis. With excess energy storage, obesity develops, leading to increased risk for type 2 diabetes and cardiovascular disease. The distribution of body fat appears to be even more important than the total amount of fat. Abdominal and, in particular, visceral adiposity is strongly linked to insulin resistance, type 2 diabetes, hypertension and dyslipidaemia, leading to increased risk of cardiovascular disease. The adverse metabolic impact of visceral fat has been attributed to distinct biological properties of adipocytes in this depot compared with other adipose tissue depots. Indeed, regional variations in the metabolic activity of fat cells have been observed. Furthermore, expression studies aiming at defining the unique biological properties of adipose tissues from distinct anatomical sites have identified depot-related differences in the protein content of fat-produced molecules. In this review we wish to summarize important results from the literature and also some recent data from our own work. The main scope is to describe the biological functions of adipose tissue, and to focus on metabolic, hormonal, and signalling differences between fat depots.

Diet-induced obesity affects expression of adiponutrin/PNPLA3 and adipose triglyceride lipase, two members of the same family

“…To induce obesity, we selected cafeteria diet feeding; the cafeteria diet is a mixed, varied, palatable, hyperlipidic diet, extensively experienced and very useful as it mimics human obesity studies [25][26][27][28][29][30][31] because it induces voluntary hyperphagia, eliciting an increase of body weight and adipose mass in rats even after a short period of time. 32 Adipose tissue is distributed in different anatomical sites with different biological functions and metabolic activities, 33,34 and we have described important regional differences regarding adiponutrin and ATGL expression. 10,19 Thus, given the importance of body fat distribution, we performed our study in different adipose tissue depots.…”

Body size and the risk of biliary tract cancer: a population-based study in China

“…It is also unclear at what age excess body fat most affects disease risk, as measurements of body size have been mainly related to a single point in time, and whether obesity independently influences biliary cancer risk, given the close connection between obesity and gallstone risk and between gallstones and biliary tract cancer. In addition, the role of abdominal obesity or body fat distribution in biliary tract cancer are unclear, although abdominal obesity is more closely associated with lipid and hormone metabolism (Giorgino et al, 2005).…”

Association of adipose tissue blood flow with fat depot sizes and adipokines in women

“…Our data therefore support the hypothesis of subcutaneous fat acting as the primary metabolic 'sink,' protecting other organs from excessive post-prandial lipid levels. Visceral fat depot size has been strongly linked to metabolic and cardiovascular diseases; 24 differences in insulin action, gene expression, metabolic responses and adipokine secretion 25,26 among fat depots could explain this difference. It has also been proposed that extrinsic factors, including depot-specific blood flow and/or innervation, 27 could contribute to distinct gene expression patterns and metabolic profiles in adipocytes in different anatomical regions.…”