Conjugated linoleic acid reduces lipid accumulationvia down-regulation expression of lipogenic genes and up-regulation of apoptotic genes in grass carp（Ctenopharyngodon idella）adipocyte in vitro

Abstract

Abstract The relationship between conjugated linoleic acid (CLA) and lipogenesis has been extensively studied in mammals and some cell lines, but it is relatively rare in fish, and the potential mechanism of action of CLA reducing fat mass remains unclear. The established primary culture model for studying lipogenesis in grass carp (Ctenopharyngodon idella) preadipocytes was used in the present study, and the objective was to explore the effects of CLA on intracellular lipid and TG content, fatty acid composition, and mRNA levels of adipogenesis transcription factors, lipase and apoptosis genes in grass carp adipocytes in vitro. The results showed that CLA reduced the size of adipocyte and lipid droplet, decreased the content of intracellular lipid and TG, which was accompanied by a significant downregulation of mRNA abundance in the transcriptional regulators (PPARγ, C/EBPα, SREBP-1c ), lipase genes(LPL、 FAS、ACC) and decreasing the content of SFAs, n-6 PUFA, increasing the content of MUFA and n-3 PUFA in primary grass carp adipocyte. In addition, CLA induced adipocyte apoptosis through downregulated anti-apoptotic gene(Bcl-2 ) mRNA level, upregulated pro-apoptotic genes(TNF-α, Bax, Caspase-3, and Caspase-9) mRNA level in a dose-dependent manner. These findings suggest that CLA can act on grass carp adipocytes through various pathways, including decreasing adipocyte size, altering fatty acid composition, restraining adipocyte differentiation, promoting adipocyte apoptosis, and thereby reducing lipid accumulation.