Adipose tissue white

Additional roles traditionally recognised for white adipose tissue include thermal insulation (as in the blubber of sea mammals) and mechanical protection to internal organs. However, in recent years it has become apparent that the function of white adipose tissue is much more extensive. This follows from the discovery that it is a major endocrine organ, secreting a diverse... 

Little attempt has been made to develop drugs targeted specifically to white adipose tissue and the production of adipokines. It is likely, however, that there will be an increasing emphasis on this approach to the pharmacological treatment of obesity-related diseases, given the current views on the centrality of the adipokines to these disorders. It is, of course, the diseases that obesity leads to, rather than obesity itself, that constitute the main medical challenge. 

Trayhurn P, Wood IS (2004) Adipokines inflammation and Hie pleiotropic role of white adipose tissue. Br J Nutr 92 347-355... 

Tissue-Specific Expression. In the adult rodent, PPARy is expressed in brown and white adipose tissue, and at lower levels in intestine, retina, skeletal muscle, and lymphoid organs. In human, PPARy is most abundantly expressed in white adipose tissue and at lower levels in skeletal muscle, the heart, and liver, but not in lymphoid tissues, although PPARy has been identified in macrophages in human atheromas. 

PPARy White adipose tissue, atherosclerotic lesions Insulin-sensitizing and glucoselowering re-directs TG from non-adipose tissues and visceral adipose depots for storage in subcutaneous adipose tissue slowed progression of atherosclerosis Fatty acids, eico-sanoids Th iazolid i ned iones pioglitazone (Actos ), rosiglita-zone (Avandia ) Type 2 diabetes, (insulin resistance, metabolic syndrome)... 

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... 

Maeda H, Hosokawa M, Sashima T, Funayama K and Miyashita K. 2005. Fucoxanthin from edible seaweed, Undariapinnatifida, shows antiobesity effect through UCP1 expression in white adipose tissues. Biochem Biophys Res Commun 332(2) 392-397. 

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. 

Figure 7.5 An interference contrast photograph of a white adipose tissue celt Note the spherical lipid droplet fills most of the cell.

The hypothesis that is formulated on the basis of these properties is as follows. The signal for increased thermogenesis, when the body temperature falls, is an increase in the level of catecholamines, probably the local concentration of noradrenaline, which will be increased via stimulation of sympathetic nervous system. The catecholamine increases the activity of triacylglycerol lipase within the brown adipose tissue, by a similar mechanism to that which occurs in white adipose tissue (Chapter 7), i.e. by an... 

In vivo, FXR is expressed in white adipose tissue (WAT) with levels decreased in the WAT of dietary (high fat) and genetic objob mice) models of obesity. ... 

The kidney brush border also possesses a carnosine transport system and there is evidence that kidney also contains an active carnosinase (Sauerhoefer et al., 2005). There is also evidence that carnosine can influence sympathetic nervous activity in kidney (Tanida et al., 2005) as well as brown (Tanida et al., 2007) and white adipose tissue (Shen et al., 2008). Other studies have shown that carnosine has antidepressant activity in rats (Tomonaga et al., 2008). In chicks, carnosine induces hyperactivity (Tsuneyoshi et al., 2007) whereas its reverse structure (L-histidinyl-13-alanine) has sedative and hypnotic effects (Tsuneyoshi et al., 2008). The mechanisms involved in remain obscure however. 

Shen, J., Yao, J. F., Tanida, M., and Nagai, K. (2008). Regulation of sympathetic nerve activity by L-carnosine in mammalian white adipose tissue. Neurosci. Lett. 44,100-104. 

An example of high-contrast resonant imaging of tissue structures with this source is shown in Figure 5.4a. Here, the white adipose tissue of a mouse omentum majus is imaged at a depth of -10 pm from the surface at a Raman shift of 2850 cm ( ump = 924 nm A tokes = 1254 nm). In contrast, for the same Raman shift, two synchronized Ti sapphire lasers (Potma et al. 2002) would typically have pump and Stokes wavelengths of -710 nm and -890 nm, respectively, and are much more strongly scattered in turbid tissue. 

Al-Hasani, H. and Joost, H. G. (2005). Nutrition-/diet-induced changes in gene expression in white adipose tissue. Best Pract. Res. Clin. Endocrinol. Metab. 19, 589-603. 

Fig. 5.5. Left panel photon emission was measured by CCD camera ex vivo in tissues dissected (left panel) after administration of a compound X. Quantitative measurement of photon emission (rightpanel) shows increased accumulation of luciferase in white adipose tissue and liver after treatment.

Okuno, A., Tamamoto, H., Tobe, K., Ueki, K., Mori, Y., Iwamoto, K., Umesono, K., Akanuma, Y., Fujiwara, T., Horikoshi, H., Yazaki, Y., and Kadowaki, T. (1998). Troglitazone Increases the Number of Small Adipocytes Without the Changes of White Adipose Tissue Mass in Obese Zucker Rats./. Clin. Invest. 101, 1354-1361. 

Figure 22.2. Effect of DHA on liver weights and white adipose tissue (WAT) weights in diet-induced lipodystrophy model mice.

Fat loss. White adipose tissue is vascularised, much like a tumour, and growth of adipose tissue is highly dependent on the building of new blood vessels (angiogenesis). Recent studies with obese mice models have shown that proapoptotic peptide, directed against blood vessels, results in decreased food intake and significant fat loss. 

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