title: Beneficial Effect of Leptin on Spatial Learning and Memory in Streptozotocin-Induced Diabetic Rats.
abstract: BACKGROUND
  Diabetes mellitus is a chronic disease which may be accompanied by cognitive impairments. The expression of the obesity gene (ob) is decreased in insulin-deficient diabetic animals and increased after the administration of insulin or leptin. Plasma leptin levels are reduced in the streptozotocin (STZ)-induced diabetic rats. Therefore, the deleterious effects of diabetes on memory may be due to the reduction of leptin.
  
  
  OBJECTIVE
  Investigate the effect of subcutaneous injection of leptin on spatial learning and memory in STZ-induced diabetic rats.
  
  
  METHODS
  Animal experimentation.
  
  
  METHODS
  The rats were divided into three groups: 1-control, 2- diabetic, and 3- diabetic-leptin. Diabetes was induced in groups 2 and 3 by STZ injection (55 mg/kg) intraperitoneally (i.p). The animals received leptin (0.1 mg/kg) or saline subcutaneously (s.c) for 10 days before behavioral studies. Then, they were examined in the Morris water maze over 3 blocks after 3 days of the last injection of leptin.
  
  
  RESULTS
  The travelled path length and time spent to reach the platform significantly increased in the diabetic group (p<0.001) and decreased with leptin treatment (p<0.01 & p<0.001 respectively); also, a significant increase in path length and time was observed between the diabetic-leptin group and the diabetic group (p<0.01, p<0.001, respectively) in the probe test.
  
  
  CONCLUSIONS
  Leptin can exert positive effects on memory impairments in diabetic rats.
authors.affiliation: Department of Physiology, North Khorasan University of Medical Sciences Faculty of Medicine, Bojnurd, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Ghasemi
authors.affiliation: Department of Physiology, Neurocognitive Research Center, Mashhad University of Medical Sciences Faculty of Medicine, Mashhad, Iran.
authors.forename: Bamdad
authors.initials: B
authors.lastname: Zendehbad
authors.affiliation: Department of Physiology, Neurocognitive Research Center, Mashhad University of Medical Sciences Faculty of Medicine, Mashhad, Iran.
authors.forename: Hoda
authors.initials: H
authors.lastname: Zabihi
authors.affiliation: Department of Physiology, Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences Faculty of Medicine, Mashhad, Iran.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Hosseini
authors.affiliation: Department of Physiology, Neurocognitive Research Center, Mashhad University of Medical Sciences Faculty of Medicine, Mashhad, Iran.
authors.forename: Mousa Al Reza
authors.initials: MA
authors.lastname: Hadjzadeh
authors.affiliation: Department of Physiology, Neurocognitive Research Center, Mashhad University of Medical Sciences Faculty of Medicine, Mashhad, Iran.
authors.forename: Parichehr
authors.initials: P
authors.lastname: Hayatdavoudi
keywords: Leptin; spatial memory; streptozotocin