Long-term consumption of fermented soybean-derived Chungkookjang enhances insulinotropic action unlike soybeans in 90% pancreatectomized diabetic rats. |
Authors: |
Kwon, DY Jang, JS Hong, SM Lee, JE Sung, SR Park, HR Park, S
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Citation: |
Kwon DY, etal., Eur J Nutr. 2007 Feb;46(1):44-52. Epub 2007 Jan 2. |
RGD ID: |
2311228 |
Pubmed: |
PMID:17200876 (View Abstract at PubMed) |
DOI: |
DOI:10.1007/s00394-006-0630-y (Journal Full-text) |
BACKGROUND: We previously reported that Chungkookjang (CKJ), fermented unsalted soybeans, exhibited better anti-diabetic action than cooked soybeans (CSB) in vitro, but its effectiveness and mechanism have not been studied in vivo. AIM OF THE STUDY: We investigated whether CKJ modulated insulin resistance, insulin secretion, and pancreatic beta-cell growth and survival in 90% pancreatectomized (Px) diabetic rats. METHODS: The Px rats weighing 201 +/- 12 g were divided into four groups and fed for 8 weeks with a CSB diet, a CKJ diet, a casein diet, or a casein diet plus rosiglitazone (20 mg/kg body weight/day). With the exception of protein sources and contents of isoflavonoid aglycones and glycosides, the composition of the diets was made identical by adding soybean oil and cellulose to a casein diet. At the end of the experimental periods, hyperglycemic clamp was performed in conscious, unstressed and overnight fasted Px rats to measure insulin secretion capacity. Insulin/IGF-1 signaling was measured by immunoblotting in isolated islets from the treated rats, and beta-cell mass, proliferation and apoptosis were also determined by immunohistochemistry. RESULTS: After 8-week administration, CSB did not modulate glucose-stimulated insulin secretion, but surprisingly, CKJ enhanced insulin secretion. In addition, CKJ potentiated insulin/IGF-1 signaling in islets via the induction of insulin receptor substrate-2 expression, leading to increasing pancreatic duodenal homeobox-1, insulin promoter transcription factor. In parallel with the enhancement of the signaling, CKJ elevated pancreatic beta-cell hyperplasia by increasing its proliferation and decreasing apoptosis, whereas CSB did not. CONCLUSION: Based on these results, the fermentation of soybeans predominantly with Bacillus subtilis generated isoflavonoid aglycones and small peptides, which improved insulinotropic action in islets of type 2 diabetic rats. Overall, the anti-diabetic action of CKJ was superior to CSB in type 2 diabetic rats.
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Objects referenced in this article
Gene |
PDX1 |
pancreatic and duodenal homeobox 1 |
Homo sapiens |
Gene |
Pdx1 |
pancreatic and duodenal homeobox 1 |
Mus musculus |
Gene |
Pdx1 |
pancreatic and duodenal homeobox 1 |
Rattus norvegicus |
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