Lipid Mobilization

Lipid Mobilization

At night, the body enters the postabsorptive state, where it relies on stored energy rather than incoming food for fuel.

Postabsorptive State and Fatty Acid Release

• During the postabsorptive state, fatty acids are released from adipose tissue to be used as an energy source.

Hormone-Sensitive Lipase (HSL)

• Human adipose tissue does not directly respond to glucagon.
• A decrease in insulin levels activates hormone-sensitive lipase (HSL).
• HSL hydrolyzes triacylglycerols, resulting in the production of fatty acids and glycerol.
• Epinephrine and cortisol can also activate HSL, influencing metabolic processes.
• The effects of these hormones on metabolism will be covered in greater detail in the subsequent chapter.

Glycerol Transport

• Glycerol, released during lipolysis, can be transported to the liver.
• In the liver, glycerol can participate in:
  • Glycolysis: The breakdown of glucose.
  • Gluconeogenesis: The synthesis of glucose.

Lipoprotein Lipase (LPL)

• Hormone sensitive lipase is active within adipose cells
• Lipoprotein lipase (LPL) is required for the metabolism of chylomicrons and very low-density lipoproteins (VLDL).
• LPL is an enzyme that releases fatty acids from triacylglycerols found in these lipoproteins.