The effect of hydroalcoholic extract of olive leaf on learning and memory deficit induced by dopaminergic neurons impairment in male rat

Background and Objective: Parkinson’s disease is one of the neurodegenerative diseases along with learning and memory disorder. Phenolic compounds in olive leaf extract have antioxidant properties. The aim of this study was to investigate the protective effect of hydroalcoholic extract of olive leaf on memory disorder induced by dopamine neurons impairment in male rat.

Materials and Methods: In this study, 42 male rats were randomly divided into 6 groups: control, sham, impairment group (6-HODA was injected into the striatum nucleus unilaterally at the end of 3rd week) and 3 extract-treated groups (rats received 50, 100 and 150 mg/kg/day of olive leaf extract orally for six weeks). The sham and impairment groups received solvent extract. Then, during three continuous weeks after toxin injection, recognition memory was examined by novel object recognition task (NORT). Apomorphine-induced rotational testing of animals was done at the third week after impairment.

Results: Dopamine neurons impairment which is caused by 6-OHDA toxin injection led to significant reduction in discrimination ratio during three weeks (p < 0.001) and consumption of 50, 100 and 150 mg/kg of olive leaf extract caused significant increase in this factor (p < 0.001).

Conclusion: Results of this study indicated that consumption of olive leaf extract leads to dopaminergic neurons protection and memory disorder reduction in the parkinsonian rat model.