Progress on the Biological Metabolic Pathways and Biomarkers of Gamma-Hydroxybutyric Acid, In Vivo

Gamma-hydroxybutyric acid is a kind of endogenous short-chain organic fatty acid, which has pharmacological effects such as euphoric and sedative, but its clinical use is strictly limited due to its high toxicity and easy addiction. In recent years, gamma-hydroxybutyric acid has been abused significantly and even used in drugassisted crimes. It is difficult to identify gamma-hydroxybutyric acid because of its physiological presence in vivo and it has fast entry and exit characteristics. In vivo, gamma-hydroxybutyric acid is synthesized by the biotransformation of gamma-aminobutyric acid, gamma butyrolactone and 1,4-butanediol, and is metabolized through the gamma-hydroxybutyric acid-gamma-aminobutyric acid, gamma-hydroxybutyric acid-succinic acid-tricarboxylic acid cycle, alpha- and beta-oxidation of gamma-hydroxybutyrate, and xenobiotic metabolism of gamma-hydroxybutyric acid. A variety of gamma-hydroxybutyric acid metabolism-related compounds are produced in the metabolic process, among which, 2,3-dihydroxybutyric acid, 3,4-dihydroxybutyric acid and glycolic acid are stable in urine, easy to identify and have a long detection window, which is expected to solve the difficult problem of gamma-hydroxybutyrate identification. The biosynthesis, catabolism and metabolism-related markers of gamma-hydroxybutyric acid were systematically and comprehensively sorted out and summarized in order to provide theoretical reference for related studies on gamma-hydroxybutyric acid identification.