Effects Of PFOS On Lipid And Glucose Metabolism In Caenorhabditis Elegans

Perfluorooctane sulfonate?PFOS?,a typical perfluorooctane sulfonate compound,has various biological toxicities including reproductive toxicity,developmental toxicity,neurotoxicity and genotoxicity.However,the molecular mechanism of PFOS-disturbed lipid metabolism and glucose metabolism is not known.Compared with higher animals,Caenorhabditis elegans?C.elegans?as a typical model organism has the ability to fully synthesize polyunsaturated fatty acids from de novo via the polyunsaturated fatty acid synthesis pathway,which combines the processes of plants and animals.In this paper,C.elegans was exposed to multiple doses of PFOS,aiming to study the effect of PFOS on the lipid metabolism and glucose metabolism of C.elegans.Detailed work and obtained results were listed as following:1.A method for methyl esterification of fatty acids from C.elegans was established.The contents of 9 typical unsaturated fatty acids in nematodes were quantitatively determined by gas chromatography-mass spectrometry?GC-MS?.High recovery rate was obtained by 2-h methyl esterification using 0.5%methyl esterification reagent?H₂SO₄/MeOH?.The ng/mL level detection limit of GC-MS was far below the PFOS concentrations in C.elegans??g/mL level?,indicating the high sensitivity of our analytical method.2.After 72-h exposure to different concentrations?0,0.01,0.1,0.5,1,5?mol/L?of PFOS at L1 phase of C.elegans,fatty acids contents in nematodes were determined using GC-MS.PFOS resulted in a decrease in fatty acid content in C.elegans,which mainly attributed to the reduction in unsaturated fatty acids;expression of key genes involved in fatty acid synthesis,such as Acetyl-CoA carboxylase-related gene acc-4,?9 desaturase related gene fat-7,was significantly down-regulated with the increase dose of PFOS?p<0.05?,indicating that PFOS might affect the expression of key enzymes in the early stage of fatty acid synthesis,resulting in decreased levels of fatty acids in C.elegans.3.Lipid metabolism is closely related to glucose metabolism and oxidative phosphorylation.The glucose content of C.elegans was decreased with the increasing PFOS concentrations after 72-h exposure.Compared with the control group,the contents of pyruvate and ATP was significantly decreased in 1?mol/L PFOS-exposed C.elegans?p<0.05?.Expression of genes involved in gluconeogenesis,glycolysis,and insulin pathway including pck-1,pyk-1,pyk-2,pfk-1.1,gpd-2,ctl-1,and daf-2 were also checked.The above results indicated that PFOS might affect the relative expression of genes associated with sugar metabolism in C.elegans,resulting in the disturbance of C.elegans glycometabolism homeostasis.Exposure of PFOS lead to the decrease in the content of fatty acids and glucose,as well as pyruvate and ATP content in the C.elegans,implying the imbalance of tricarboxylic acid cycle,which might result in the death of C.elegans.In conclusion,we established a sensitive and reliable GC-MS method for the analysis of fatty acids in C.elegans,quantitatively measured the effect of PFOS exposure on fatty acid metabolism and related gene expression in C.elegans,and further analyzed the effect of PFOS exposure on glucose metabolism and tricarboxylic acid cycle in C.elegans.The obtained results indicated that PFOS could significantly inhibit lipid metabolism,glucose metabolism,and the synthesis of ATP in C.elegans,leading to its multiple toxic effects.