Effect of Calendula officinalis hydroalcoholic extract on passive avoidance learning and memory in streptozotocin-induced diabetic rats.

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.