Growth hormone (GH) is a key hormone that promotes lipolysis. Lipolysis is the breakdown of stored fats (triglycerides) into fatty acids, releasing them into the bloodstream for energy. Several hormones influence this process, but GH plays a significant role.
How Growth Hormone Stimulates Lipolysis
Studies show that GH directly stimulates lipolysis in adipose tissue, leading to increased levels of free fatty acids in the plasma. [Reference: Adipose tissue, growth hormone (GH) stimulates lipolysis, leading to an increase in plasma free fatty acid levels and a reduction in insulin sensitivity.28-Oct-2023] This effect is observed in both human and animal studies. [Reference: Growth hormone (GH) potently and dose dependently stimulates lipolysis in humans (Hansen et al. 2002). In mice, knockout (KO) of the GH receptor renders the...] The mechanism involves the activation of hormone-sensitive lipase (HSL), a key enzyme in the lipolytic pathway. [Reference: Hormone-sensitive lipase catalyzes the rate-limiting step in the release of fatty acids from triacylglycerol-rich lipid storage droplets of...]
Other Hormones Involved in Lipolysis
While GH is a significant stimulator, it's important to note that other hormones also influence lipolysis:
- Insulin: Acts as a primary inhibitor of lipolysis. [Reference: The most important regulatory hormone in lipolysis is insulin; lipolysis can only occur when insulin action falls to low levels, as occurs during fasting.] High insulin levels suppress lipolysis.
- Glucagon: Stimulates lipolysis through the cAMP pathway, activating HSL. [Reference: Activation of protein kinase A by cyclic adenosine monophosphate (cAMP) is sufficient to promote glycogenolysis and to activate hormone‐sensitive lipase.]
- Thyroid hormone: Has a complex role, stimulating both lipogenesis (fat production) and lipolysis. The net effect depends on the level of thyroid hormone. High levels generally lead to fat loss. [Reference: TH stimulates both lipogenesis and lipolysis, although when TH levels are elevated, the net effect is fat loss (191). TH influences key metabolic pathways that...]
- Catecholamines (e.g., epinephrine, norepinephrine): These hormones also stimulate lipolysis through cAMP-mediated activation of HSL.
Practical Insights
Understanding the hormonal regulation of lipolysis is crucial in various fields, including:
- Weight management: Manipulating GH levels (under medical supervision) or influencing other hormones involved in lipolysis could potentially assist in weight loss strategies.
- Metabolic disorders: Dysregulation of lipolysis is involved in conditions like obesity, type 2 diabetes, and metabolic syndrome.
- Pharmacology: Drugs targeting HSL or other enzymes involved in lipolysis are being developed for treating metabolic disorders.
