How are fatty acids released from adipose tissue?
Fatty acids are released from adipose by hydrolysis of their stored form, triacylglycerol. Hydrolysis is initiated by activation of the hydrolytic enzyme, hormone sensitive lipase (HSL). HSL is a phospho-dephospho enzyme which is active in the phospho- form. Phosphorylation of HSL is stimulated by the hormones epinephrine, norepinephrine, cortisol and ACTH. These hormones bind to the surface of the adipocyte, where they activate adenyl cyclase, initiating a typical c-AMP-mediated phosphorylation cascade, terminating with phosphorylation of HSL. After release from adipocytes, unesterified fatty acids are transported in the blood bound to serum albumin to tissues such as liver, heart and muscle, where they are taken up and oxidized.
