Evaluation of the Protective Effect of Olive Leaf Extracts on Anxiety-like Behaviors in an Animal Model of Parkinson\'s Disease

BACKGROUND AND OBJECTIVE: Oxidative stress is one of the main causes of Parkinson's disease. Mood disorders such as anxiety are commonly reported in these patients. Olive leaf extracts have strong antioxidative and neuroprotective properties due to the presence of various phenolic compounds. The aim of the present study was to investigate the effects of olive leaf extracts on anxiety-like behaviors in an animal model of Parkinson's disease, using elevated plus maze test. METHODS: In this experimental study, 42 rats were divided into six groups (seven rats per group): control, sham, patient and treatment (receiving extracts at doses of 50, 100 and 150 mg/kg) groups. The control group did not receive any injections, whereas the sham and patient groups received saline solutions and the treatment group received 50, 100 and 150 mg/kg of olive leaf extracts via gavage for seven weeks. All groups, except the control and sham groups, were administered unilateral 6-hydroxydopamine in the striatum, using a stereotactic device, and an animal model of Parkinson's disease was established. Three weeks after toxin injections, anxiety-like behaviors were assessed, using the elevated plus maze test. FINDINGS: The injection of 6-hydroxydopamine caused a reduction in the time of animals’ entry into the open arm and the number of entries. Administration of different concentrations of the extract caused an increase in the mentioned parameters in all treatment groups, compared to the patient group. CONCLUSION: The results showed that oral administration of olive leaf extracts caused a significant decrease in anxiety-like behaviors, induced by 6-hydroxydopamine in an animal model of Parkinson's diseas