Adipose tissue control

Sundin, U. (1981) Brown Adipose Tissue. Control of Heat Production. Development During Ontogeny and Cold Adaptation. University of Stockholm. ISBN 91-7146-152-3. 

Facilitates passage of glucose, K., Mg across cellular membranes of skeletal and cardiac muscle, adipose tissue controls storage and metabolism of carbohydrates, protein, fats. Promotes conversion of glucose to glycogen in liver. 

Appetite control is a complex function of the brain that regulates feeding behaviour. This function integrates cognitive and emotional factors with a complex array of signals from the gastrointestinal tract and from adipose tissue. 

Ketogenesis is regulated at three cmcial steps (1) control of free fatty acid mobihzation from adipose tissue (2) the activity of carnitine palmitoyltransferase-1 in hver, which determines the proportion of the fatty acid flux that is oxidized rather than esteri-fied and (3) partition of acetyl-CoA between the pathway of ketogenesis and the citric acid cycle. 

Figure 25-8. Control of adipose tissue lipolysis. (TSH, thyroid-stimulating hormone FFA, free fatty acids.) Note the cascade sequence of reactions affording amplification at each step. The lipolytic stimulus is "switched off" by removal of the stimulating hormone the action of lipase phosphatase the inhibition of the lipase and adenylyl cyclase by high concentrations of FFA the inhibition of adenylyl cyclase by adenosine and the removal of cAMP by the action of phosphodiesterase. ACTFI,TSFI, and glucagon may not activate adenylyl cyclase in vivo, since the concentration of each hormone required in vitro is much higher than is found in the circulation. Positive ( ) and negative ( ) regulatory effects are represented by broken lines and substrate flow by solid lines.

A Variety of Mechanisms Have Evolved for Fine Control of Adipose Tissue Metabolism... 

In addition to fiber and carbohydrate content, protein intake from legumes may have weight-loss benefits for obese individuals just because proteins enhance post-meal satiety (Rolls, 1995). However, a possible specific role for phytoestrogens in obesity has been postulated through the modulation of the satiety response, a neuroendocrine mechanism controlled by leptin (a hormone secreted by adipose tissue and already known to be regulated by... 

Among 27 prospective and case-control studies, 16 reported inverse associations between some carotenoids and CVDs, taking plasma or serum concentration as carotenoid biomarkers (11 of 16 studies), dietary intake (5 of 16 studies), or adipose tissue level (1 of 16 studies). With regard to the findings from the studies based on CVD risk, only two of seven presented significant inverse associations of carotenoids, particularly lycopene and P-carotene, whereas five studies of nine showed inverse correlations between myocardial infarcts and lycopene and/or P-carotene the others presented no associations. ... 

Importantly, the mutant chicken exhibits lower levels of lutein and zeaxanthin in plasma and several other tissues in comparison with the control chicken, and that difference is already apparent in 1-day-old chickens and remains in 28-day-old chickens fed the same diet (Connor et al., 2007). In the WHAM chickens, the levels of lutein in the plasma, retina, skin, adipose tissue, liver and heart, respectively, have been found to be only 8%, 10%, 18%, 33%, 52%, and 60% of the corresponding levels in control chickens. Even though the diet in these chickens included three times more lutein than zeaxanthin and these ratios have been present in the plasma of both the control and WHAM chickens, there was a preferential accumulation of zeaxanthin over lutein in their retinas. 

The major hormone-sensitive control point for the mobilization of fat and the (f-oxidation pathway is the effect of phosphorylation on the activity of the hormone-sensitive lipase of the adipose tissue. The major direct control point for (f oxidation is the inhibition of carnitine acyl-... 

Liver histopathology and diarrhea recorded in all treated groups vs. none in controls. The 1000 mg/kg diet was the only ration to adversely affect the weight of all organs analyzed. After 5 weeks on PCP-free diet, residues were still measurable in adipose tissues of all treated birds (Stedman et al. 1980)... 

The role of GPR55 is unknown at present. Transcripts have been identified in various human tissues, including brain, spleen, ileum and omental (but not subcutaneous) adipose tissue. This last observation may point to a role in regulation of central adiposity, but blood pressure control has also been suggested as a possible function [88]. Specific ligands and/or knockout animals will be required to probe further the role of this receptor. 

The most recent National Human Adipose Tissue Survey did not detect endrin in adipose tissues from the general U.S. population (Stanley 1986). Endrin also was not detected in adipose breast tissue from breast cancer patients (n=5) or controls (n=5) in the United States (Djordjevic et al. 1994). A 1984 study based on autopsied adipose tissue from 141 cadavers from six Canadian Great Lakes municipalities showed no detectable concentrations of endrin (detection limit 2.4 ppb) (Williams et al. 1988). In a 1990-91 survey, only very low levels of endrin (average concentration 3.27 ng/g (ppb) range 0.23-8.56 ng/g [ppb] lipid)... 

Mirex has been found in human adipose tissue (Burse et al. 1989 Kutz et al. 1974). Although the route of exposure was not specified, exposure was probably via the inhalation, oral, and dermal routes. Levels of 0.16-5.94 ppm and 0.3-1.13 ppm in males and females, respectively, were found in tissue samples taken either from postmortem examinations or during surgery (Kutz et al. 1974). The adipose tissue samples came from individuals who lived in areas in which mirex was used extensively in a program to control fire ants. Adipose tissue levels of mirex ranging from 0.03 to 3.72 ppm have been found in residents living near a dump site in Tennessee (Burse et al. 1989). 

Triglyceride and fatty acid synthesis are promoted by insulin stimulation of liver and adipose tissues by causing the phosphorylation of the first and controlling enzyme in the pathway acetyl-CoA carboxylase (see Section 6.3.2). This enzyme catalyses the formation of malonyl-CoA and requires both allosteric activation by citrate and covalent modification for full activity. 

Adipose tissue, fat, is usually thought of as a metabolically sluggish energy reservoir and mechanical and thermal insnlator. It has proved to be much more than that. Adipose tissue influences the body weight, the inunnne response, the control of blood pressure, hemostasis, bone mass, and the fnnctions of thyroid and reproductive glands. It does these things largely on the basis of synthesis and release of a family of adipocyte peptide hormones. 

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