title: IGF-1 induction by acylated steryl β-glucosides found in a pre-germinated brown rice diet reduces oxidative stress in streptozotocin-induced diabetes.
abstract: BACKGROUND
  The pathology of diabetic neuropathy involves oxidative stress on pancreatic β-cells, and is related to decreased levels of Insulin-like growth factor 1 (IGF-1). Acylated steryl β-glucoside (PR-ASG) found in pre-germiated brown rice is a bioactive substance exhibiting properties that enhance activity of homocysteine-thiolactonase (HTase), reducing oxidative stress in diabetic neuropathy. The biological importance of PR-ASG in pancreatic β-cells remains unknown. Here we examined the effects of PR-ASG on IGF-1 and glucose metabolism in β-cells exposed to oxidative stress.
  
  
  RESULTS
  In the present study, a pre-germinated brown rice (PR)-diet was tested in streptozotocin (STZ)-induced diabetic rats. Compared with diabetic rats fed control diets, the PR-diet fed rats showed an improvement of serum metabolic and neurophysiological parameters. In addition, IGF-1 levels were found to be increased in the serum, liver, and pancreas of diabetic rats fed the PR-diet. The increased IGF-1 level in the pancreas led us to hypothesize that PR-ASG is protective for islet β-cells against the extensive injury of advanced or severe diabetes. Thus we examined PR-ASG to determine whether it showed anti-apoptotic, pro-proliferative effects on the insulin-secreting β-cells line, INS-1; and additionally, whether PR-ASG stimulated IGF-1 autocrine secretion/IGF-1-dependent glucose metabolism. We have demonstrated for the first time that PR-ASG increases IGF-1 production and secretion from pancreatic β-cells.
  
  
  CONCLUSIONS
  These findings suggest that PR-ASG may affect pancreatic β-cells through the activation of an IGF-1-dependent mechanism in the diabetic condition. Thus, intake of pre-germinated brown rice may have a beneficial effect in the treatment of diabetes, in particular diabetic neuropathy.
authors.affiliation: Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, United States of America. susuki@georgiahealth.edu
authors.forename: Seigo
authors.initials: S
authors.lastname: Usuki
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Tsai
authors.forename: Keiko
authors.initials: K
authors.lastname: Morikawa
authors.forename: Shota
authors.initials: S
authors.lastname: Nonaka
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Okuhara
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kise
authors.forename: Robert K
authors.initials: RK
authors.lastname: Yu
mesh_terms: D000215:Acylation / Q000187:drug effects; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001786:Blood Glucose / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D004032:Diet; D005786:Gene Expression Regulation / Q000187:drug effects; D018525:Germination / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005960:Glucosides / Q000494:pharmacology*; D006019:Glycolysis / Q000187:drug effects; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008954:Models, Biological; D012275:Oryza / Q000737:chemistry*; D018384:Oxidative Stress / Q000187:drug effects*; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species
chemical_list: D001786:Blood Glucose; D003470:Culture Media; D005960:Glucosides; D007328:Insulin; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D007334:Insulin-Like Growth Factor I; D005954:Glucosephosphate Dehydrogenase; D005947:Glucose