Lipolysis, simple process with big impact
Its all about changes of triglyceride (TG) into fatty acid (FA) and glycerol. Lipolysis converts the most abundant energy storage, triglyceride, into ready to use fatty acid. This process happened in mane places at the entire human body. The most important place is in the adipose tissue where 95% of body’s TG stored. The other spot is in muscle, liver tissue and extracelular fluid.
In adipose tissue lipolysis is done due to demand for systemic FA. However, lipolysis in muscle and liver is happened due to increase demand of local energy needs. This is necessary since lipolysis turnover in those tissue happend faster than lipolysis in adipose tissue. Thus this process is necessary for compensation of short term lack of FA. In the muscle and liver, FA will be used for oxidation or reesterification. Both processed are driven by homone sensitive lipase (HSL).
HSL also control lypolisis process in adipose tissue. This enzyme is called hormone sensitive since its significantly regulated by presence of both insulin and cathecolamine level in human body. Signal from cathecolamine is received by beta adrenergic receptor while insulin is received by insulin receptor. Those receptor activation then activate downstream process including HSL activity.
Lipolysis is an important process in whole body fuel metabolism and disturbance in this process implicates some disease. Increasing FA in circulation as the end product of lipolysis process would inhibit body glucose disposal. Excess of lypolisis induces hypertriglyceridemia and leading to atherosclerosis. Disturbance in FA regulation could manifest from certain conditions including obesity, stress, aging and diabetes.
Coppack SW et al. In vivo regulation of lipolysis in humans. Journal of Lipid Research, 1994, 35, 177-194.