The potential role of AMP-activated protein kinase (AMPK) in regulating lipid metabolism in the Manila clam Ruditapes philippinarum under hyposalinity stress

Lipid metabolism is considered to play a crucial role in assisting aquatic animals to adapt to environmental change. In the Manila clam, Ruditapes philippinarum, the involvement of AMPK in the regulation of lipid metabolism under hyposalinity stress is not well understood. Hence, in this study, two populations (TS wild population and FZ culture population) of R. philippinarum were employed in experimentation on the effects of hyposalinity stress. The enzyme activities of triglyceride, total cholesterol, and free fatty acid in the clam hepatopancreas significantly decreased under hyposalinity. Conversely, a significant increase in AMPK gene expression was observed. Under hyposalinity stress, the levels of SREBP-1c, ACC, and SCD gene expression were decreased, whereas the levels of CPT1 and ACOX1 expression were increased. The results indicate that the AMPK gene may be activated under hyposalinity. This activation could subsequently inhibit lipid metabolism, promote lipid oxidation, provide energy for osmotic pressure regulation, and maintain energy balance. Our study delivers important insights into the molecular mechanisms by which AMPK regulates lipid metabolism, energy metabolism, and osmotic regulation in R. philippinarum under hyposalinity stress. Additionally, it offers a valuable reference for the breeding and farming of R. philippinarum.