聖約翰草對3T3-L1脂肪細胞生成作用之影響

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Title:	聖約翰草對3T3-L1脂肪細胞生成作用之影響
Other Titles:	Effects of Saint John's wort on adipogenesis in 3T3-L1 adipocytes
Authors:	陳品錡 Chen, Pin-Chi
Contributors:	陳珠亮 Chen, Chu-Liang 東海大學畜產與生物科技學系
Keywords:	脂肪細胞;細胞分化;脂質代謝;聖約翰草 adipocytes;differentiation;lipid metabolism;Saint John''s wort;Hypericum perforatum L.
Date:	2006
Issue Date:	2011-04-07T05:56:37Z (UTC)
Abstract:	本研究以3T3-L1前脂肪細胞為試驗模式，探討聖約翰草（Saint John’s wort; Hypericum perforatum L）甲醇萃取物對脂肪細胞生成作用（adipogenesis）的影響。由oil-Red O脂質染色結果判定聖約翰草花萃取物比莖或葉之萃取物，更能抑制脂肪細胞分化脂質的堆積。於細胞不同分化階段添加聖約翰草花萃取物，以 oil-Red O脂質染色與 GPDH活性測定結果發現，在分化前期經聖約翰草處理的細胞其最後的分化並未受到影響，儘管其分化前期的擴增作用明顯較低；而聖約翰草抑制分化的作用主要見於分化後期處理的細胞。西方點墨法（western blot analysis）與相對定量反轉錄聚合?連鎖反應（relative RT-PCR）分析顯示，聖約翰草處理會抑制一些扮演基因轉錄調節角色的細胞分化標幟基因，如 CCAAT/enhancer-binding protein β （C/EBPβ）以及 peroxisome proliferator-activated receptor γ （PPARγ）之表現，並可能透過此途徑而降低下游基因之表現，例如 adipocyte-fatty acid binding protein（A-FABP）、leptin、perilipin、與 hormonal sensitive lipase （HSL）。西方點墨法分析進一步顯示，聖約翰草花萃取物處理細胞之 protein kinase C (PKC）α、βI與 ζ蛋白質表現並未如對照組一般隨著細胞分化而表現降低，顯示聖約翰草可能藉由減少 PKC降解而抑制脂肪細胞的分化。我們同時發現當分化成熟的脂肪細胞曝露於聖約翰草花萃取物，其脂質分解作用（lipolysis）明顯增加；相對定量反轉錄聚合?連鎖反應結果顯示，此時其脂質分解作用相關基因，如 HSL、perilipin與 glycerol kinase mRNA表現亦明顯增加。最後，以細胞計數亦證明聖約翰草可抑制前脂肪細胞的分裂。由上述結果可知，聖約翰草花萃取物具多重作用而影響脂肪細胞生成，包括抑制前脂肪細胞的分裂、分化早期的細胞擴增、分化基因的表現、以及成熟脂肪細胞的脂質分解作用。 This study aimed to investigate the effects of Saint John’s wort (SJW)-methanol extracts on adipogenesis using the 3T3-L1 preadipocyte culture system. The results of oil-Red O staining showed that cells treated with SJW extracts during differentiation had lower degrees of lipid contents than the control cells, with the flower extracts had more inhibitory effects than the stem or leaf extracts. Treatment with the SJW flower extracts during early stages (day 0 to 2) did not inhibit cell differentiation as indicated by the results of oil-Red O staining and GPDH activity assay of the cells on day 6, but the treatment did decrease the mitotic clonal expansion. Cells treated with the flower extracts at late stages led to low degrees of differentiation compared with the untreated cells. Additionally, the expressions of the adipocyte differentiation-related transcription factors, such as CCAAT/enhancer-binding protein β (C/EBPβ), and peroxisome proliferator-activated receptor γ (PPARγ) were inhibited in the SJW flower extract-treated cells. And these may contribute to the decreased levels of the adipocyte-specific genes, including adipocyte-fatty acid binding protein (A-FABP), leptin, perilipin, and hormonal sensitive lipase (HSL), that are known to be expressed in the late stages of adipocyte differentiation. Furthermore, the levels of protein kinase Cs (PKCs), which usually decline along the adipocyte differentiation process as observed in the control cells, were unaltered in the SJW-treated cells, indicating that SJW extracts hindered the activation and thereafter downregulation of PKCs during adipocyte differentiation. The mRNA levels of lipolysis-related genes, namely perilipin, HSL, and glycerol kinase, were increased in the SJW-treated cells, suggesting that SJW flower extract treatment also increased the lipolytic activities in mature adipocytes. Finally, the SJW extracts were able to inhibit preadipocyte proliferation as estimated by cell enumeration. Overall, the SJW-methanol extracts inhibit adipogenesis by affecting different facets of the process, including the inhibition of preadipocyte division and mitotic clonal expansion during early stages of differentiation, the modulation of adipocyte differentiation through differentiation-related genes, and the elevation of lipolysis activities.
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