title: Olive leaf extract suppresses messenger RNA expression of proinflammatory cytokines and enhances insulin receptor substrate 1 expression in the rats with streptozotocin and high-fat diet-induced diabetes.
abstract: Type 2 diabetes, characterized by hyperglycemia and hyperlipidemia, is a metabolic disease resulting from defects in both insulin secretion and insulin resistance. Recently, olive leaf has been reported as an anti-inflammatory, antioxidant, and antidiabetic agent. This study sought to investigate whether olive leaf extract can improve the insulin resistance and inflammation response in rats with type 2 diabetes induced by high-fat diet and streptozotocin. After administering olive leaf extract for 8 weeks (200 and 400 mg/kg body weight), rats given the higher dose showed significantly lower blood glucose, serum total cholesterol, and triglyceride levels compared with those of diabetic control rats (P < .05). Results of oral glucose tolerance tests, homeostasis model assessment of insulin resistance, and messenger RNA (mRNA) expression of tumor necrosis factor α and interleukin (IL) 6 in the liver show significantly decreased glucose level in rats given either dose of olive leaf extract (P < .05). Both olive leaf extract-treated groups showed significantly increased insulin receptor substrate 1 expression (P < .05). Tumor necrosis factor α, IL-6 and IL-1β mRNA expressions in epididymis adipose tissue were significantly lower in rats that received higher dose of olive leaf extract (P < .05). Lymphocyte infiltration was not observed in these rats. The results suggest that olive leaf extract may attenuate insulin resistance by suppressing mRNA expression of proinflammatory cytokines and elevating of insulin receptor substrate 1 expression.
authors.affiliation: Major in Food and Nutrition, College of Human Ecology, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
authors.forename: Ya-Nan
authors.initials: YN
authors.lastname: Liu
authors.affiliation: Division of Biology Science, College of Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
authors.forename: Ji-Hye
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Major in Food and Nutrition, College of Human Ecology, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
authors.forename: Hyunjin
authors.initials: H
authors.lastname: Park
authors.affiliation: Major in Food and Nutrition, College of Human Ecology, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address: hskim@sookmyung.ac.kr.
authors.forename: HyunSook
authors.initials: H
authors.lastname: Kim
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D059305:Diet, High-Fat; D007249:Inflammation / Q000097:blood / Q000188:drug therapy*; D018836:Inflammation Mediators / Q000378:metabolism; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D031658:Olea; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D012333:RNA, Messenger / Q000378:metabolism; D017208:Rats, Wistar; D013311:Streptozocin
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D055504:Insulin Receptor Substrate Proteins; D010936:Plant Extracts; D012333:RNA, Messenger; D013311:Streptozocin
keywords: Insulin receptor substrate-1; Insulin resistance; Olive leaf extract; Proinflammatory cytokines; Type 2 diabetes