title: The effects of insulin, glucagon, glutamate, and glucose infusion on blood glutamate and plasma glucose levels in naive rats.
abstract: BACKGROUND
  Elevated levels of glutamate in brain fluids, in the context of several neurodegenerative conditions, are associated with a worsened neurological outcome. Because there is a clear relationship between brain glutamate levels and glutamate levels in the blood, and an association of the latter with stress, the purpose of this study was to investigate the effects of glucose, insulin, and glucagon on rat blood glutamate levels.
  
  
  METHODS
  Rats received either 1 mL/100 g of rat body weight (BW) intravenous isotonic saline (control), 150 mg/1 mL/100 g BW intravenous glucose, 75 mg/1 mL/100 g BW intravenous glutamate, 50 g/100 g BW intraparitoneal glucagon, or 0.2 UI/100 g BW intraparitoneal insulin. Blood samples were subsequently drawn at 0, 30, 60, 90, and 120 minutes for determination of blood glutamate and glucose levels.
  
  
  RESULTS
  We observed a significant decrease in blood glutamate levels at 30 minutes after injection of glucose (P<0.05), at 30 and 60 minutes after injection of insulin (P<0.05), and at 90 and 120 minutes after injection of glucagon. Plasma glucose levels were elevated after infusion of glutamate and glucose but were decreased after injection of insulin.
  
  
  CONCLUSIONS
  The results of this study demonstrate that glucose, insulin, and glucagon significantly reduce blood glutamate levels. The effect of insulin is immediate and transient, whereas the effect of glucagon is delayed but longer lasting, suggesting that the sensitivity of pancreatic glucagon and insulin-secreting cells to glutamate is dependent on glucose concentration. The results of this study provide insight into blood glutamate homeostasis and may assist in the implementation of new therapies for brain neuroprotection from excess glutamate.
authors.affiliation: Division of Anesthesiology, Soroka Medical Center, Beer-Sheva, Israel. zlotnika@bgu.ac.il
authors.forename: Alexander
authors.initials: A
authors.lastname: Zlotnik
authors.forename: Benjamin Fredrick
authors.initials: BF
authors.lastname: Gruenbaum
authors.forename: Yael
authors.initials: Y
authors.lastname: Klin
authors.forename: Shaun Evan
authors.initials: SE
authors.lastname: Gruenbaum
authors.forename: Sharon
authors.initials: S
authors.lastname: Ohayon
authors.forename: Eyal
authors.initials: E
authors.lastname: Sheiner
authors.forename: Ruslan
authors.initials: R
authors.lastname: Kuts
authors.forename: Matthew
authors.initials: M
authors.lastname: Boyko
authors.forename: Yoav
authors.initials: Y
authors.lastname: Bichovsky
authors.forename: Yoram
authors.initials: Y
authors.lastname: Shapira
authors.forename: Vivian I
authors.initials: VI
authors.lastname: Teichberg
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D005934:Glucagon / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D018698:Glutamic Acid / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D010179:Pancreas / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D018698:Glutamic Acid; D005934:Glucagon; D005947:Glucose