以卵巢剔除小鼠探討數種植物雌激素化合物/萃物之雌激素相關生理活性

Study on estrogenic activity in vivo of some phytoestrogenic compound / extracts in ovariectomized mice

許婉貞(Wang-chen Hsu)

指導教授 ： 黃青真

國立臺灣大學/生命科學院/微生物與生化學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.02977

摘要

因雌激素分泌逐漸減少，使停經期婦女發生更年期症候群。停經後婦女則面臨代謝症候群之風險增高、增加罹患心血管疾病的機率，且易有骨質疏鬆的情形。由於荷爾蒙替代療法被發現副作用，會造成一些疾病的風險升高。故許多研究致力探討具選擇性之雌激素替代物，例如:植物性雌激素。本研究目的為探討已在細胞實驗具雌激素活性的植物雌激素化合物/萃物在體內是否具雌激素活性，並探討其對缺乏雌激素所引起之代謝症候群及骨質疏鬆之預防功效。
八週齡C57BL/6J母鼠進行偽手術或卵巢剔除手術(OVX)。第一批實驗動物分成五組:偽手術小鼠分別餵食Basal Diet (SB組, n=4)或 3 g RRR-α-tocopherol (TOH) / kg diet (STOH組, n=6)；OVX mice分別餵食Basal (B組, n=5)、3 g TOH / kg diet (TOH組, n=5)或2 mg / kg diet Estradiol (E2組, n=5)。第二批動物分成五組: 偽手術小鼠餵食Basal diet (SB組, n=8)；OVX mice分別餵食Basal diet (B組, n=6)、 20 g苜蓿芽乙酸乙酯萃物/ kg diet (AEA組, n=6)、20 g月季花80%甲醇萃物/kg diet (RS組, n=4) 與2 mg Estradiol / kg diet (E2組, n=5)。實驗動物皆在給予實驗飼料14週後犧牲。
在體內雌激素生理生化反應方面，E2組之子宮重量、子宮和子宮周圍脂肪組織creatine kinase活性及肝臟ERαmRNA表現量高於B組(p＜0.05)，但其子宮ERα和β mRNA表現量較B組低 (p＜0.05)。樣品方面，TOH組之子宮周圍脂肪creatine kinase活性和子宮ERβmRNA表現量高於B組(p＜0.05)。AEA和RS組之肝臟ERα mRNA表現量顯著高於B組(p＜0.05)。TOH、AEA及RS組均不會造成子宮重量增高。陰道抹片的結果，E2組停滯在E期，而B組延長D期。TOH組5隻小鼠中有2隻延長D期，2隻為正常，1隻延長在E期。AEA組的6隻小鼠有3隻延長E期，另外3隻延長D期。RS組則和AEA組的情況相同。
而代謝症候群方面，B組之體重、脂肪重量和血糖皆顯著比SB組高 (p＜0.05)，顯示雌激素缺乏會誘發代謝症候群。而E2組之體重、脂肪重量、血糖、胰島素阻抗、血清和肝臟三酸甘油酯皆低於B組(p＜0.05)，顯示補充雌激素後可以防止代謝症候群。TOH組之脂肪相對重量較B組低(p＜0.05)。AEA組之血糖、胰島素阻抗和血清三酸甘油酯顯著低於B組(p＜0.05)。而RS組之血糖、胰島素阻抗、血清三酸甘油酯和膽固醇皆比B組低(p＜0.05)。
在預防骨質疏鬆方面，AEA組在第3週之鈣吸收顯著高於B組(p＜0.05)。E2組和SB組之鈣吸收則與B組無顯著差異。B組之股骨乾重/體重、灰分重/體重和鈣量/乾重之比例較SB組低 (p＜0.05)，且其腰骨鈣量較SB組低 ( p＜0.05)，顯示雌激素缺乏會減少骨鈣的保留。而E2組之股骨乾重/體重、灰分重/體重、鈣量和鈣量/乾重比例顯著高於B組(p＜0.05)，另外，其腰骨乾重、灰分重、乾重/體重、灰分重/體重和骨鈣量皆較B組高( p＜0.05)，顯示補充雌激素具調節骨鈣的作用。
綜之，本實驗以卵巢剔除鼠實驗模式，證實雌二醇之生理活性，並以其為正對照，驗證RRR-α-生育醇、苜蓿芽乙酸乙酯萃物及月季花80%甲醇萃物於體內可以呈現部份雌激素之生理功能，但不會促進子宮增生，且對缺乏雌激素之代謝症候群及骨質流失具部份保護效果。

關鍵字

更年期 ； 雌激素活性 ； 代謝症候群 ； 骨質疏鬆

並列摘要

Due to a decrease in estrogen production, women frequently suffer from menopausal syndrome at this age . In addition, post-menopausal women are at high risk for metabolic syndrome and cardiovascular disease as well as osteoporosis. As unfavorable side effects have been demonstrated in a clinical trial, hormone replacement therapy (HRT) is no longer recommended. In stead, research and development of ideal selective estrogen receptor modulars (SERMs), including phytoestrogens, are implemented. This study aims at examing the in vivo estrogenic response of three phytoestrogenic compound/extracts screened by in vitro assays. These are RRR-tocopherol, ethyl acetate extract of alfalfa sprout (AEA) and 80% methanol extract of Rosa chinesis (RS). Their potential in preventing metabolic syndrome and osteoporosis induced by estrogen deficiency were also evaluated.
C57BL/6J mice were sham-operated (Sham) or ovariectomized(OVX) at 8 week of age. In experiment 1 five groups were included: SB group (Sham mice fed basal diet, n=4), STOH group (Sham mice fed basal diet supplemented with 3 g RRR-α-TOH / kg diet, n=6), B group (OVX mice fed basal diet, n=5), E2 group (OVX mice fed basal diet supplemented with 2 mg estradiol / kg diet, n=5) and TOH group (OVX mice fed basal diet supplemented with 3 g RRR-α-tocopherol (TOH) / kg diet, n=5). Five groups were included in Experiment 2: SB, B and E2 groups were the same as above, AEA group (OVX mice fed basal diet supplemented with 20 g AEA) and RS group (OVX mice fed basal diet supplemented with 20 g RS). Mice were sacrificed after feeding experimental diets for 14 weeks.
The estrogenic response of estradiol was demonstrated by significantly higher uterus weight, the creatine kinase activity of uterus and white adipose tissue and ERα mRNA expression of liver, the lower mRNA expression of ERα and ERβ of the uterus in the E2 group compared to those in the B group (p＜0.05). The creatine kinase activity of white adipose tissue and ERβ mRNA expression of uterus were significantly higher in TOH compared ti those in the B group (p＜0.05). The ERα mRNA expressions of liver were also higher in AEA and RS groups than in the B group (p＜0.05). The uterus weight of TOH, AEA and RS groups was not different from that of the B group (p>0.05). Results of the vaginal smear examination indicated that E2 group persisted on the estrus stage while B group showed a prolonged diestrus stage. Two out of five TOH group of mice showed prolonged diestrus, one showed prolonged estrus, and the remaining two mice had somewhat regular cycle. Three out of six AEA group of mice showed a prolonged estrus, and the remaining three showed a prolonged diestrus. Similar results were observed in the RS group of mice. These results suggest that all three samples showed partial estrogenic response in these OVX mice.
The B group had higher final body weight, white adipose tissue weight and serum glucose than SB group (p＜0.05), indicating metabolic syndrome associated with estrogen deficiency. Body weight, white adipose tissue weight, serum glucose, HOMA-IR index, serum and hepatic triglyceride of the E2 group were significantly lower than those of the B group (p＜0.05),indicating estrogen effectively prevent metabolic syndrome in the OVX mice. Relative white adipose tissue weight of the TOH group was significantly lower than that of the B group (p＜0.05). The AEA group had lower serum glucose, HOMA-IR index and serum triglyceride than the B group (p＜0.05). The serum glucose, HOMA-IR index, serum triglyceride and cholesterol were also significantly lower in the RS group compared to the B group (p＜0.05).
The B group had less femur dry weight /BW, ash weight/BW and Ca/dry weight as well as Ca content of lumbar than the SB group (p＜0.05), indicating less well bone in the OVX state. Dry weight /BW, ash weight/BW, Ca content and Ca/dry weight of femur, dry weight, ash weight, dry weight/BW, ash weight/BW and Ca content of lumbar were significantly higher in the E2 group compared to those in the B group (p＜0.05), indicating the protective effect of estrogen on bone.
In conclusion, the estrogenic response as well as the protection of estrogen on metabolic syndrome and bone were demonstrated in the present OVX mice study. Using the estrogen-treated OVX mice as a positive control, RRR-α-tocopherol, EA extract of alfafa and 80% methanol extract of Rosa chinesis were demonstrated to show partial estrogenic activity in vivo without a uterotrophic effect. These phytoestrogenic compound/extract also showed partial protection in the metabolic syndrome but limited protection in bone.

並列關鍵字

phytoestrogen ； ovariectomized mice ； estrogenic response ； metabolic syndrome ； osteoporosis

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