lipotropin

Lipotropin is a historical term used to describe a pituitary-derived peptide once believed to promote fat mobilization and lipolysis. In mid-20th century research, lipotropin was described as a factor from anterior pituitary extracts that could reduce body fat or plasma lipids in animal models. Over time, the term fell out of common use as understanding of pituitary peptides improved and the nature of lipotropic activity was questioned.

Chemically, lipotropin is connected to proopiomelanocortin (POMC), the large precursor protein from which several hypothalamic and pituitary hormones are derived. Beta-lipotropin refers to the C-terminal portion of POMC and is one of the peptides produced by POMC processing. Through proteolysis, beta-lipotropin can give rise to other peptides, such as beta-endorphin, which complicates attribution of a distinct, independent lipolytic role to intact lipotropin.

Physiological interpretation has evolved: early reports proposed a specific lipolytic effect on adipocytes, but subsequent studies suggested that what was labeled lipotropin may reflect activities of POMC-derived peptides, particularly beta-endorphin, rather than a unique circulating hormone with a defined metabolic function. As a result, the term lipotropin is rarely used in modern endocrine literature, and beta-lipotropin is typically considered within the broader family of POMC-derived peptides.

Clinical relevance is minimal in contemporary medicine. There are no approved therapies based on lipotropin, and current research tends to focus on the roles of POMC-derived peptides in energy balance, stress response, and analgesia rather than on a separate lipotropin hormone.