Essay On Adipose Tissue

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Fasting upregulates PPARγ in adipocyte AMPK activated
Adipose
Structure and Function
There are two categories of human adipose tissue, subcutaneous adipose tissue (SCAT) and visceral adipose tissue (VAT). Adipose tissue can be further classified as white adipose tissue (WAT) and brown adipose tissue (BAT). Adipose is composed of adipocytes, pre-adipocytes, fibroblasts, and immune cells. A vascular network runs through adipose while nerves innervate the tissue as well. Adipocytes found in WAT contain a single large lipid droplet which is considered an organelle. The nucleus and other organelles are displaced to the side of the adipocyte close to the membrane [1].
BAT functions in heat production through thermogenesis. WAT comprises the majority of adipose found in adults. WAT adipocytes store fatty acids (FA) esterified with glycerol in the form of triacylglycerols (TAG). Circulating FAs are attached to lipoproteins are transported into adipocytes via lipoprotein lipase. Glucose and other non-lipid entities may be converted into lipids via lipogenesis within adipocytes. Adipocytes also serve an endocrine function secreting adipocytokines such as adiponectin, leptin and resistin [1].
Under a fasted state adipocytes respond to a high glucagon:insulin ratio by hydrolyzing TAGs into free FAs and glycerol. The FAs may be taken up by other cells and used to produce energy through β-oxidation within the mitochondrial matrix. The glycerol may enter gluconeogenesis [1].
Add a brief synopsis of what happens with pre-adipocytes and adipogenesis under fasted condtions
AMPK
Structure and Function
Adenosine monophosphate kinase (AMPK) is considered the energy sensor of cells. When AMPK is activated under conditions of low intracellular energy ...

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...ts and other data. Fasting for 15 hours increases the AMP/ATP ratio in adipocytes. The binding of AMP to AMPKγ allows for LKB1 to phosphorylate AMPKα Thr172. Activated AMPK may phosphorylate eIF2α rendering it inactive. PPARγ mRNA may continue to be transcribed, but it cannot be translated while eIF2α is inactive meaning less PPARγ is expressed. Less C/EBPα mRNA is translated as well due to inactivated eIF2α. A reduction in PPARγ translates to a decrease in C/EBPα activation and the feed forward loop between these complexes is also reduced. Under fasted conditions adipocytes are attempting to conserve energy by down-regulating anabolic processes such as lipogenesis through the down-regulation of lipogenic initiation factors such as PPARγ.
There is sufficient evidence both in vitro and in vivo to conclude that fasting down-regulates PPARγ in adipocyte AMPK activated.

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