title: Antihyperglycemic action of rhodiola-aqeous extract in type1-like diabetic rats.
abstract: BACKGROUND
  Rhodiola rosea (Rhodiola) is a plant in the Crassulaceae family that grows in cold regions of the world. It is mainly used in clinics as an adaptogen. Recently, it has been mentioned that Rhodiola increases plasma β-endorphin to lower blood pressure. Thus, the present study aims to investigate the antidiabetic action of Rhodiola in relation to opioids in streptozotocin-induced diabetic rats (STZ-diabetic rats).
  
  
  METHODS
  In the present study, the plasma glucose was analyzed with glucose oxidase method, and the determination of plasma β-endorphin was carried out using a commercially available enzyme-linked immunosorbent assay. The adrenalectomy of STZ-diabetic rats was used to evaluate the role of β-endorphin. In addition, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting analysis were performed to investigate mRNA and protein expressions.
  
  
  RESULTS
  Rhodiola-water extract dose-dependently lowered the plasma glucose in STZ-diabetic rats and this action was reversed by blockade of opioid μ-receptors using cyprodime. An increase of plasma β-endorphin by rhodiola-water extract was also observed in same manner. The plasma glucose lowering action of rhodiola-water extract was attenuated in bilateral adrenalectomized rats. In addition, continuous administration of rhodiola-water extract for 3 days in STZ-diabetic rats resulted in an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle and a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver. These effects were also reversed by blockade of opioid μ-receptors.
  
  
  CONCLUSIONS
  Taken together, rhodiola-water extract improves hyperglycemia via an increase of β-endorphin secretion from adrenal gland to activate opioid μ-receptors in STZ-diabetic rats.
authors.affiliation: Department of Nursing, Tzu Chi College of Technology, Hualien City 97005, Taiwan. ncs838@yahoo.com.tw.
authors.forename: Chiang-Shan
authors.initials: CS
authors.lastname: Niu
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Chen
authors.forename: Ho-Shan
authors.initials: HS
authors.lastname: Niu
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006943:Hyperglycemia / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors; D029771:Rhodiola / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D001615:beta-Endorphin / Q000097:blood / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D047908:Intracellular Signaling Peptides and Proteins; D010936:Plant Extracts; D012333:RNA, Messenger; D017450:Receptors, Opioid, mu; C495694:Slc2a4 protein, rat; D014867:Water; D001615:beta-Endorphin; C582554:Pck1 protein, rat; D010729:Phosphoenolpyruvate Carboxykinase (GTP)