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Regulation of Adipocyte Lipolysis

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Presentation on theme: "Regulation of Adipocyte Lipolysis"— Presentation transcript:

1 Regulation of Adipocyte Lipolysis
Catecholamines Epinephrine & Norepinephrine Beta Adrenergic Receptors Stimulate Alpha Adrenergic Receptors Inhibit Insulin Inhibitory

2 Catecholamines Stimulatory Inhibitory B-Adrenergic Receptors
Activates Stimulatory G-Protein Activates Adenylate Cyclase Generates cAMP Activates cAMP-dependent protein kinase Phosphorylates HSL & Perilipins Break down triglycerides Inhibitory A-Adrenergic Receptors Activates Inhibitory G-protein Inhibits Adenylate Cyclase

3 Catecholamines stimulate HSL to break down triglycerides to fatty acids and glycerol
Fatty acids and glycerol are released into the blood and circulated to other body tissues

4 ATGL Adipose Triglyceride Lipase
Enzyme that may be responsible for catalyzing the initial steps of triglyceride hydrolysis. Zimmermann et al. (2004) HSL knock-out mice showed an accumulation of diglycerides, suggesting that additional lipases may be present that can hydrolyze the first ester bond of triglycerides Still controversial

5 Lipoprotein Lipase (LPL) Phosphatidylinositol 3-Kinase (PI3K)
Insulin Lipoprotein Lipase (LPL) Phosphatidylinositol 3-Kinase (PI3K) Hydrolyzes Phosphorylates Plasma Triglycerides Phosphodiesterase-3 Degrades Into cAMP FFA

6 Insulin & LPL

7 PI3K Insulin Phosphorylates LPL Hydrolyzes triglycerides in the blood to increase FFA levels PI3K Inhibits lipolysis in adipose cells Mediates insulin-stimulated glucose uptake Phosphodiestesterase-3 Degrades

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