GABA-mediated regulation of lipid metabolism: a conserved relation with diverse physiological significances.

Gamma-aminobutyric acid (GABA) is a four-carbon non-proteinogenic amino acid that is primarily known for its role as an inhibitory neurotransmitter in mammals. It is synthesized from glutamate by the enzyme L-glutamic acid decarboxylase and metabolized via the GABA shunt pathways. GABA is known to influence various metabolic processes, and recent studies have shown its influence on lipid metabolism. This review explores the distinct relationship between GABA and lipid metabolism by highlighting their role in physiological processes in animals, plants, and microalgae. In animals, GABA acts as a metabolic regulator, particularly in the liver, where it mitigates diseases associated with fat accumulation, such as obesity, hyperlipidemia, and type 2 diabetes mellitus, by modulating adipogenesis and lipogenesis (fat synthesis and accumulation), lipolysis (fat breakdown), and thermogenesis and oxidation (energy expenditure). Conversely, in plants and algae, it plays a vital role in stress responses and developmental processes by suppressing lipid membrane degradation and by promoting lipid accumulation. We also delve into the metabolic pathways through which GABA interacts with lipid metabolism, including its connection to the tricarboxylic acid cycle and its involvement in the GABA shunt. This review underscores the multifaceted nature of GABA, revealing its critical contribution to lipid homeostasis, highlighting its relevance in metabolic disorders in animals, and stress responses in both plants and algae. Despite being a relatively underexplored area, the GABA-lipid relationship holds substantial significance due to its involvement in varied physiological processes, suggesting promising avenues for future therapeutic research and biotechnological applications.