title: Protection against brain tissues oxidative damage as a possible mechanism for improving effects of low doses of estradiol on scopolamine-induced learning and memory impairments in ovariectomized rats.
abstract: BACKGROUND
  Regarding the anti-oxidative effects on the central nervous system, the possible protection against brain tissues oxidative damage as a possible mechanism for improving effects of low doses of estradiol on scopolamine-induced learning and memory impairments was investigated in ovariectomized (OVX) rats.
  
  
  METHODS
  The OVX rats treated by (1) vehicle, (2) scopolamine, and (3-4) scopolamine plus estradiol (20 or 20 or 60 μg/kg). Estradiol was administered (20 or 60 μg/kg, intraperitoneally) daily for 6 weeks after ovariectomy. The rats were examined for learning and memory using passive avoidance test. Scopolamine (2 mg/kg) was injected 30 min after training in the test. The brains were then removed to determine malondialdehyde (MDA) and thiol contents.
  
  
  RESULTS
  Scopolamine shortened the time latency to enter the dark compartment in (P < 0.01). Compared to scopolamine, pretreatment by both doses of estradiol prolonged the latency to enter the dark compartment (P < 0.01). The brain tissues MDA concentration as an index of lipid peroxidation was decreased (P < 0.05). Pretreatment by estradiol lowered the concentration of MDA, while it increased thiol content compared to scopolamine (P < 0.05 and P < 0.01).
  
  
  CONCLUSIONS
  These results allow us to suggest a protection against brain tissues oxidative damage as a possible mechanism for improving effects of low doses of estradiol on scopolamine-induced learning and memory impairments in OVX rats.
authors: Department of Physiology, Shahid Sadoghi University of Medical Sciences, Yazd, Iran.
authors: Seyed Hassan
authors: SH
authors: Hejazian
authors: Neurocognitive Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors: Sareh
authors: S
authors: Karimi
authors: Neurocognitive Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors: Mahmoud
authors: M
authors: Hosseini
authors: Neurogenic Inflammation Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors: Seyed Mojtaba
authors: SM
authors: Mousavi
authors: Department of Biochemistry, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors: Mohammad
authors: M
authors: Soukhtanloo
keywords: Estradiol; learning; memory; oxidative stress; scopolamine