Regulation Of Rat Preadipocytes' Proliferation And Differentiation By AA And DHA

Healthy, disease-free, 20-day-aged, male SD rats were selected as experimental material in this paper. Rat preadipocytes were isolated and cultured in vitro to investigate the regulation of arachidonic acid (AA) and docosahexaenoic acid (DHA) on cell's proliferation and differentiation. The expression of peroxisome proliferation activated receptor-?2 (PPAR-γ2) and cyclooxygenases-2 (COX-2) mRNA in adipocytes were also detected that treated by lower and higher concentration of AA and DHA. The objective of this study is to supply basis for clarifying the metabolism of AA and DHA on preadipocytes proliferation and differentiation. The proliferation of cells were detected by trypan blue exclusion, methyl thiazolyl tetrazolium (MTT) assay, Hoechst33342 fluorescence staining and flow cytometry method. Trypan blue exclusion and MTT results showed that AA promoted rat preadipocytes living ration, especially with a concentration of 120 μmol/L (P <0.01), and 120 μmol/L AA can reduce the cellular ration during G1 period of the adipocytes cell cycle, increase it during PrI period. Morphologic changes of rat adipocyte apoptosis induced by 160μmol/L AA at 48 hours and reduce the effect AA on cell's proliferation. DHA can reduce the proliferation of rat's preadipocytes, and 160 μmol/L DHA has remarkable effection compared with control group(P<0.05). By observed cells morphologic changes, oil red o staining lipids assay, vanilline total fat and total protein assay method to detect regulation of AA and DHA on adipocytes differentiation. The results are as follow: 40-80 μmol/L AA decreased the content of fat of adipocytes and inhibition preadipocyes transform to adipocytes, especially with 80 μmol/L AA(P<0.01), but 160 μmol/L AA has a opposition effect. DHA can inhibite cells differentiation, especially with 160 μmol/L DHA(P<0.05). The expression of PPAR-γ2 and COX-2 mRNA were detected by reverse transcriptase-polymerase chain reaction(RT-PCR).The results showed that lower concentration AA (40 μmol/L) and higher concentration of DHA (160 μmol/L) all could decrease the expression of PPAR-γ2, especially with 160 μmol/L DHA(P<0.01). The regulation of AA and DHA on COX-2 was complicated, 40 μmol/L AA and 160 μmol/L DHA up-regulated the expression of COX-2 mRNA(P<0.05), but 160 μmol/L AA and 40 μmol/L DHA down-regulated COX-2 mRNA of rat adipocytes(P<0.01).