title: Effect of Calendula officinalis hydroalcoholic extract on passive avoidance learning and memory in streptozotocin-induced diabetic rats.
abstract: BACKGROUND
  Medicinal plants, owing to their different mechanisms such as antioxidants effects, may improve learning and memory impairments in diabetic rats. Calendula officinalis (CO), has a significant antioxidant activity.
  
  
  OBJECTIVE
  To examine the effect of hydroalcoholic extract of CO on passive avoidance learning (PAL) and memory in streptozotocin (STZ)-induced diabetic male rats.
  
  
  METHODS
  A total of 32 adult male Wistar rats were randomly allocated to four groups: Control, diabetic, control + extract of CO and diabetic control + extract of CO groups with free access to regular rat diet.
  
  
  METHODS
  Diabetes in diabetic rats was induced by single intraperitoneal injection of 60 mg/kg STZ. After confirmation of diabetes, oral administration of 300 mg/kg CO extract to extract-treated groups have been done. PAL was tested 8 weeks after onset of treatment, and blood glucose and body weight were measured in all groups at the beginning and end of the experiment.
  
  
  METHODS
  The statistical analysis of data was performed by ANOVA followed by least significant difference post-hoc analysis.
  
  
  RESULTS
  Diabetes decreased learning and memory. Effect of CO extract in retention test (after 24 and 48 h) has been shown a significant decrease in step-through latency and increase in time spent in the dark compartment part. Also the extract partially improved hyperglycemia and reduced body weight.
  
  
  CONCLUSIONS
  Taken together, CO extract can improve PAL and memory impairments in STZ-diabetic rats. This improvement may be due to its antioxidant, anticholinergic activities or its power to reduce hyperglycemia.
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran ; Department of Pharmacognosy and Pharmaceutical Biotechnology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Shirin
authors.initials: S
authors.lastname: Moradkhani
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Iraj
authors.initials: I
authors.lastname: Salehi
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Abdolmaleki
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Komaki
keywords: Calendula officinalis; diabetes mellitus; learning; memory; passive avoidance