Effect of Nelumbinis semen powder on anti-obesity and anti-diabetic properties in high-fat diet-induced obese C57BL/6 mice

국문 초록 (Abstract)

본 연구는 연자육분말을 5%, 10%를 첨가한 식이를 5주령 수컷 C57BL/6 마우스에게 12주간 급여하여 항비만 및 항당뇨 효과를 알아보기 실시하였다. 실험군은 정상식이군 (CON), 고지방식이군 (HFD), 고지방식이+연자육분말5% (HFD-5%NS), 고지방식이+연자육분말10% (HFD-10%NS)의 4개군으로 나누었다. 항비만 측정항목으로는 식이섭취량, 체중, 지방조직무게, 혈액지질분획을, 항당뇨 항목은 혈당, 복강내 당부하검사, 인슐린저항성 등이었다. 식이섭취량은 연자육분말 첨가식이군 모두에서 HFD군에 비해 높았으나 식이효율은 낮았다 (p < 0.05). 부고환지방과 신장주변지방은 HFD군에 비해 HFD-5%NS군에서 평균 33.9% 감소5하였으며 혈청 LDL-C과 TG 수준은 평균 29.5% 감소하였고 HDL-C는 25.8% 증가하였다(p < 0.05). 연자육분말 첨가식이군 모두에서 고지방식이군에 비해 AI 및 CRF 수치는 감소하여 심혈관 보호효능을 보였다. 또한, 고지방식이군에 비해 연자육분말 첨가식이군은 혈청 ALT를 감소시키고, 간 조직내 지방구의 수와 크기를 감소시켜 간보호효과를 보였다(p<0.05). 혈당은 연자육분말 첨가군 모두에서 HFD군에 비해 낮았고, 복강내 당부하 검사결과 역시 HFD군에 비해 평균 13.8%의 감소를 확인하였다 (p < 0.05). 인슐린저항성은 HFD군에 비해 HFD-5%NS군과 HFD-10%NS군에서 26.8%, 47.3% 개선되었다 (p < 0.05). 이에 항비만과 항당뇨 관련 유전자 발현정도를 확인한 결과, 지방분해 인자인 PPAR-α 단백질 발현량은 연자육분말 첨가군 모두에서 HFD군에 비해 평균 1.5배 증가하였다. 인슐린 감수성 관련인자인 PPAR-γ 단백질 발현량 역시 HFD군에 비해 평균 1.5배 증가하였고 당 수용체인 GLUT4 단백질은 CON군보다도 높은 발현량을 보였다 (p < 0.05). 한편, 염증인자인 TNF-α 단백질 발현량은 HFD군에 비해 연자육분말 첨가군서 평균 0.65배 감소하였다 (p < 0.05). 결론적으로, 본 연구의 연자육분말 첨가는 고지방식이군에 비해 내장지방 감소, 혈청지질 개선, 간보호효과를 보였으며 혈당과 내당능 및 인슐린 저항성 개선효과를 나타내었다. 연자육 분말의 항비만 및 항당뇨 효능은 PPAR-α, PPAR-γ, GLUT4, TNF-α 등 관련 단백질 발현량의 조절작용에 의한 것으로 사료되었다.

다국어 초록 (Multilingual Abstract)

Nelumbinis semen extract showed a high antioxidant activity as compared to 40 species of Korean natural and medicinal plants. The purpose of this study was to determine the effect of Nelumbinis semen (NS) powder with regards to its anti-obesity and anti-diabetic properties on high-fat diet-induced obese C57BL/6 mice for 12 weeks. We categorized mice into 4 groups (CON, control diet; HFD, high fat diet; HFD-5%NS, high fat diet with Nelumbinis semen powder 5%; HFD-10%NS, high fat diet with Nelumbinis semen powder 10%). To determine anti-obesity effects, the body weight, food intake, organ weight, fat weight, biochemical profiles, and H&E staining were measured. Food intake was higher in HFD-5%NS and HFD-10%NS groups, whereas food efficiency ratio was highest in the HFD group among the 4 groups (p < 0.05). HFD-5%NS significantly reduced the body weight and fat weight, including epididymal fat and perirenal fat, by 39.1% and 28.6%, respectively, and also reduced the serum triglyceride levels by 20.6%, as compared to HFD. HFD-5%NS and HFD-10%NS groups showed hepatoprotective properties in that they reduced the serum ALT levels (p < 0.05) while also reducing fat globules, both in size and number, in liver as compared to the HFD group. The random blood glucose levels, intraperitoneal glucose tolerance test and serum insulin levels were all assessed in order to determine anti-diabetic properties. HFD-5%NS and HFD-10%NS significantly regulated the blood glucose and improved the glucose intolerance, a 12.5% and 15.0% reduction of AUC of IPGTT respectively, and a 26.8% and 47.3% improvement homeostatic model assessment insulin resistance (HOMA-IR) respectively compared to HFD (p < 0.05). Also, with regards to gene expressions related to anti-obesity and anti-diabetes, HFD-5%NS and HFD-10%NS increased PPAR-α protein expression 1.7 times and 1.3 times respectively, as compared to HFD. HFD-5%NS and HFD-10%NS increased PPAR-γ protein expression 1.4 times and 1.6 times respectively, as compared to HFD, and increased GLUT4 protein expression even more than CON. However, HFD-5%NS and HFD-10%NS decreased TNF-α protein expression 0.7 times and 0.6 times respectively, as compared to HFD (p < 0.05). Thus, given these findings, this study confirmed anti-obesity and anti-diabetic efficacy of Nelumbinis semen powder. Therefore, it is anticipated that the data in this study provides fundamental data for Nelumbinis semen powder’s functional and health-promoting uses, as related to anti-obesity and anti-diabetes.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Materials and Methods 5
• 2.1 Sample preparation 5
• 2.2 Antioxidant activity of Nelumbinis semen extract 5
• 2.3 Animal breeding and experimental design 6
• 2.4 Diet preparation and formula composition for animal study 7
• 2.5 Blood and organ collection 9
• 2.6 Blood chemical analysis 9
• 2.7 Histopathological analysis 9
• 2.8 Blood glucose measurement 10
• 2.9 Intraperitoneal glucose tolerance test 10
• 2.10 Western blot analysis 10
• 2.11 Statistical analysis 11
• 3. Results 12
• 3.1 Antioxidant activity of Nelumbinis semen extract 12
• 3.2 Nelumbinis semen powder reduced body weight gain and food efficiency ratio 12
• 3.3 Nelumbinis semen powder reduced organ and fat weight per unit 14
• 3.4 Nelumbinis semen powder improved blood chemical profiles 16
• 3.5 Nelumbinis semen powder reduced the number and size of fat vacuoles in liver 18
• 3.6 Nelumbinis semen powder alleviated hyperglycemia 20
• 3.7 Nelumbinis semen powder alleviated glucose intolerance 22
• 3.8 Protein expression of PPAR-α, TNF-α, PPAR-γ and GLUT4 25
• 4. Discussion 30
• 5. Summary and Conclusion 39
• References 41
• 국문초록 47