Obesogen은 일반적으로 비만을 유도하는 내분비계 교란물질(endocrine disrupting chemicals, EDCs)을 말한다. 이러한 obesogen의 작용 기전을 구명하고, 이를 억제 하는 기능성 식품 소재를 연구하는 것은 내분비계 교란물질로 인한 질병 치료와 건강증진에 주요한 방법이다. 현재 obesogen에 의한 비만을 억제하는 기능성 식품 소재 연구는 매우 제한적이거나 전무하다. 따라서 본 연구에서는 내분비계 교란물질에 대하여 주요한 노출기전으로 알려진 식품으로 섭취 가능한 내분비계 교란물질(BPA, BPS, and BPF; DOTP, and TOTM; EtP, MeP, and PrP)을 선정하여 비만유도 효과를 평가하였다. 본 연구의 첫 번째 목표는 3T3-L1 세포에서 obesogen들의 지질축적 유도 모델 확립이다. 분화유도 hormone (insulin, IBMX, dexamethasone)을 사용하여 지방전구세포의 분화를 유도하였다. 그 결과 dexamethasone과 obesogen을 동시에 처리한 경우 obesogen의 유무에 관계없이 지질 축적이 유도되어 차이를 확인 할수 없었다. 하지만 dexamethasone을 처리하지 않은 경우 BPA, BPS, BPF, EtP 및 DOTP 처리군에서 지질 축적이 농도 유의적으로 증가하였다. 또한 bisphenols 처리군에서 가장 많은 지질 축적이 유도되었다. 따라서 우리는 BPA와, BPA의 대체제인 BPS 및 BPF에 의해 발현이 증가되는 adipogenic transcription factors (ATFs)를 RT-PCR과 western blot assays로 조사하였다. 그 결과 모든 BPA, BPS 및 BPF 처리군에서 ATFs의 발현 증가가 확인 되었지만 obesogen 그룹간의 차이는 보이지 않았다. 따라서 우리는 비스페놀류 중 가장 널리 사용되는 BPA를 이용하여 obesogenic 작용기전을 구명하였다. 우리는 BPA처리 후 harvest time(1, 3, 6, 12, 24 및 48 시간)에 따른 master ATFs의 발현 변화를 측정하였으며, PPARγ의 antagonist인 GW9662와 agonist인 rosiglitazone를 이용하여 BPA의 PPARγ 발현유도를 확인하였다. PPARγ 및 C/EBPα의 단백질 발현 수준은 BPA 처리군에서 대조군에 비해 유의적으로 증가하였으며, 분화 48시간에서 더 명확하게 나타났다. 또한 BPA로 유도된 PPARγ 발현은 GW9662 처리로 인해 완전히 억제 되었다. 이러한 결과는 BPA가 PPARγ의 발현을 유도하여 비만 효과를 유발함을 시사한다. 또한 우리는 BPA로 유도된 3T3-L1세포의 분화와 비만 마우스에서 Cirsium setidens Nakai 추출물(CNE)의 anti-obesogenic 효과를 평가하였다. CNE는 분화 초기(48 hours) 및 분화 말단(10 days)에서 BPA로 유도된 PPARγ 및 C/EBPα의 발현을 억제하였으며 BPA 유도 지질 축적을 유의적으로 억제하였다. BPA로 유도된 비만 마우스 모델은 10주 동안 BPA(500 μg/kg/day)를 경구 투여하여 확립되었다. BPA로 유도된 비만 마우스 모델에서 CNE와 병용 투여된 그룹은 체중이 감소되었으며, 부고환 백색지방조직의 무게와 지방세포 크기 또한 정상 대조군과 유사하게 감소되었다. 혈장 지질 분석 결과에서는 BPA 투여군은 triglyceride 수치가 증가했지만 CNE 병용 투여군에서는 유의한 감소를 보였다. 또한 BPA 투여로 지방조직에서 발현 이 유도된 master ATFs와 lipogenesis 관련 효소는 CNE 병용 투여로 유의적으로 감소하였다. 이러한 결과는 CNE가 BPA 처리로 유발된 비만과 비만관련 대사 질환을 예방하는 기능성 식품 소재로서 잠재적인 가능성을 나타낸다. 본 연구는 내분비계 교란물질(Endocrine disrupting chemical)들이 obesogen으로서 비만을 유도하는 작용기전을 3T3-L1 지방세포 및 C57BL/6J 마우스 모델에서 확인하였으며, 강원도 산채 자원 중에서 소비량이 많은 곤드레 추출물에 대한 항오비소겐 효능을 평가하였다. 본 연구에서 수행된 항오비소겐 효능 평가 모델 및 작용기전 연구법은 향후 식품의약품안전처 신규기능성 평가의 모델로도 활용가치가 높을 것으로 사료된다.
Obesogenic endocrine disrupting chemicals (EDCs), commonly called obesogens, play an important role in adipogenesis. For this reason, elucidating the obesogenic mechanisms of EDC and designing foods that can inhibit it may be important in treating obesity-induced diseases and promoting health. To the best of our knowledge, there are very limited or no studies on the development of functional food ingredients that suppress EDC-induced obesity. Therefore, the objectives of this thesis were to compare the obesogenic effects of each EDCs, investigate the obesogenic mechanism, and develop the food ingredients that inhibit their obesogenic effects. In this study, EDCs including bisphenols [bisphenol A (BPA), bisphenol S (BPS) and bisphenol F (BPF)], phthalates [dioctyl terephthalate (DOTP) and tris (2-ethylhexyl) trimellitate (TOTM)] and parabens [ethylparaben (EtP), methylparaben (MeP) and propylparaben (PrP)] mainly ingested through food were selected to evaluate their obesogenic effects. Therefore, this study was to find out the effects of obesogens and their alternatives on adipogenesis in 3T3-L1 cells. Preadipocytes were treated with a MDI cocktail [3-isobutyl-1-methylxanthine (IBMX), dexamethasone, and insulin] as adipogenic inducer to which obesogens. Simultaneous treatment of obesogen and dexamethasone had no significant difference in the adipogenic effect with or without obesogens. However, in the absence of dexamethasone, treatment with BPA, BPS, BPF, EtP and DOTP during adipocyte differentiation (days 0-10 post-induction) resulted in a significant induction of lipid accumulation. Also, the obesogen-induced lipid accumulation was the highest in the bisphenols-treated group compared with other obesogen groups. We further investigated the expression of adipogenic transcription factors (ATFs) in 3T3-L1 cells induced by 20 μM of BPA, BPS, or BPF at both the mRNA and protein levels in terminal adipogenesis, as determined through reverse transcription-polymerase chain reaction and western blot assays. Since the use of BPA is the most widespread among bisphenols, we decided to investigate the obesogenic mechanism action of BPA. We investigated the changes in the expression of master ATFs according to the harvest time in the early stage (1, 3, 6, 12, 24, and 48 hours) in BPA-treated groups. Moreover, the underlying mechanism of the obesogenic effect of BPA was confirmed using the peroxisome proliferator-activated receptor γ (PPARγ) antagonist (GW9662) and agonist (rosiglitazone). The protein expression levels of PPARγ and C/EBPα were significantly increased after BPA treatment compared with MI (IBMX and insulin) treatment, and were more evident at 48 hours of differentiation time. Furthermore, increased PPARγ expression was completely inhibited by GW9662 treatment (11.82 ± 3.94 and 15.82 ± 6.25%, respectively) at 48 hours of differentiation time. These results suggest that BPA induce the expression of PPARγ, triggering the obesogenic effects. Lastly, the anti-obesogenic effects of Cirsium setidens Nakai extract (CNE) were evaluated as a functional food ingredient in BPA-induced 3T3-L1 adipocyte differentiation and obese C57BL/6J mice. CNE suppressed the expression of BPA-induced master ATFs during early differentiation (48 hours) as well as terminal differentiation (10 days). In addition, CNE completely inhibited the BPA-induced lipid accumulation in 3T3-L1 adipocyte. The BPA-induced obese mouse model was established by oral administration of BPA (500 μg/kg/day) for 10 weeks. In the group of mice co-administered with BPA and CNE, the weight gain of mice was reduced compared to the group administered with only BPA. The weight of epididymal white adipose tissue (WAT) and adipocyte size was reduced in BPA-administered group similar to the normal control group. In the results of plasma lipid profile analysis, the BPA-administered group was also increased triglyceride levels, but showed a significant decrease in the CNE co-administered group. The increased expression of ATFs and lipogenesis-related enzymes were reduced in CNE co-administered WAT. These findings indicate that CNE could potentially be used as a promising natural means to prevent the BPA-induced obesity and the obesity-related metabolic diseases. In conclusion, this study confirmed the mechanism action of EDCs to induce obesity as an obesogen in 3T3-L1 adipocytes and C57BL/6J mouse models and evaluated the anti-obesogen effect of CNE which distributed mainly in the Gangwon Province. The mechanism action of EDCs and anti-obesogen efficacy evaluation model developed through this study is considered to be valuable as a model for the evaluation of new functional ingredients by the Ministry of Food and Drug Safety.
ABSTRACTCONTENTSLIST OF TABLESLIST OF FIGURESABBREVIATIONSI. General IntroductionII. Literature review2.1. Obesity2.2. Endocrine disrupting chemicals (EDCs)2.3. Obesogen2.4. Establishment of an in vitro method for obesogen2.5. Establishment of an in vivo method for obesogen2.6. Development of functional food ingredients for obesogenIII. Part 1: Environmental obesogens (bisphenols, phthalates and parabens) and their adipogenic impacts in 3T3-L1 cells3.1. Abstract3.2. Introduction3.3. Materials and methods3.3.1. Chemicals and reagents3.3.2. Cell culture and differentiation3.3.3. Cell viability3.3.4. Oil red O staining assay3.3.5. Statistical analysis3.4. Results3.4.1. Effects of bisphenols, phthalates, and parabens on cell viability3.4.2. Effects of bisphenols (BPA, BPS, and BPF) on lipid accumulation in the presence of various dexamethasone concentrations3.4.3. Effects of phthalates (DOTP and TOTM) on lipid accumulation in the presence of various dexamethasone concentrations3.4.4. Effects of parabens (EtP, MeP and PrP) on lipid accumulation in the presence of various dexamethasone concentrations3.4.5. Comparison of adipogenic effects of bisphenols, phthalates, and parabens on lipid accumulation in the absence of dexamethasone3.5. Discussion3.6. ConclusionIV. Part 2: Molecular mechanism action of bisphenols-induced adipogenesis in 3T3-L1 adipocyte4.1. Abstract4.2. Introduction4.3. Materials and methods4.3.1. Chemicals and reagents4.3.2. Cell culture and differentiation4.3.3. Cell viability4.3.4. Oil red O staining4.3.5. RNA extraction and semi-quantitative reverse transcription polymerase chain reaction4.3.6. Western blot analysis4.3.7. Statistical analysis4.4. Results4.4.1. Effects of bisphenols on cell viability in terminal stage of 3T3-L1 cells differentiation4.4.2. mRNA expression of adipogenic transcription factors in terminal stage of BPA-, BPS-, and BPF-treated 3T3-L1 cells differentiation4.4.3. Protein expression of adipogenic transcription factors in terminal stage of BPA-, BPS-, and BPF-treated 3T3-L1 cells differentiation4.4.4. Effects of BPA, rosiglitazone and GW9662 on cell viability in early and terminal stage of 3T3-L1 cells differentiation4.4.5. Changes in protein expression of master adipogenic transcription factors in early stage of BPA-treated 3T3-L1 cells differentiation4.4.6. Adipogenic effects of BPA in 3T3-L1 adipocytes with suppressed PPARγ expression4.5. Discussion4.6. ConclusionV. Part 3: Cirsium setidens Nakai extract attenuates bisphenol A-induced 3T3-L1 adipocyte differentiation via the suppression of adipogenesis-related transcription factors5.1. Abstract5.2. Introduction5.3. Materials and methods5.3.1. Chemicals and reagents5.3.2. Sample preparation5.3.3. Cell culture and differentiation5.3.4. Cell viability5.3.5. Oil red O staining5.3.6. Western blot analysis5.3.7. Statistical analysis5.4. Results5.4.1. Effects of CNE on cell viability in early and terminal stage of BPA-treated 3T3-L1 adipocytes5.4.2. Effect of CNE on the expression levels of adipogenic transcription factors in early stage of BPA-treated 3T3-L1 adipocytes5.4.3. Effect of CNE on lipid accumulation in BPA-treated 3T3-L1 adipocytes5.4.4. Effect of CNE on the expression levels of adipogenic transcription factors in terminal stage of BPA-treated 3T3-L1 adipocytes5.4.5. Effect of CNE on the expression levels of lipogenesis-related enzymes in terminal stage of BPA-treated 3T3-L1 adipocytes5.5. Discussion5.6. ConclusionVI. Part 4: Cirsium setidens Nakai extract attenuates bisphenol A-induced obese C57BL/6J mice through regulation of adipogenesis and lipogenesis6.1. Abstract6.2. Introduction6.3. Materials and methods6.3.1. Sample preparation6.3.2. Animal and experimental design6.3.3. Biochemical analysis6.3.4. Histological analysis6.3.5. Western blotting analysis6.3.6. Statistical analysis6.4. Results6.4.1. Effect of CNE administration on the body and tissue weight in BPA-induced obese C57BL/6J mice6.4.2. Effect of CNE administration on the adipose tissue in BPA-induced obese C57BL/6J mice6.4.3. Effect of CNE administration on the plasma lipid profile in BPA-induced obese C57BL/6J mice6.4.4. Expression levels of adipogenic transcription factors in adipose tissue of BPA-induced obese C57BL/6J mice6.4.5. Expression levels of lipogenesis-related enzymes in adipose tissue of BPA-induced obese C57BL/6J mice6.5. Discussion6.6. ConclusionVII. ConclusionVIII. ReferencesAbstract in Korean