Melissa officinalis aqueous extract ameliorates 6-hydroxydopamine-induced neurotoxicity in hemi-parkinsonian rat

ABSTRACT Background and Objective: Parkinson's disease (PD) is an age-related neurodegenerative disorder with massive loss of dopaminergic neurons in the substantia nigra pars compacta. L-Dihydroxyphenylalanine (L-DOPA) substitution is still the gold standard therapy for PD. However, there has been little information available on neuroprotective and regenerative therapies for PD. Due to the neuroprotective and anti-oxidant property of Melissa officinalis (MO), this research study was done to evaluate whether MO could improve behavioral and structural changes in an experimental model of early PD in rat. Materials and Methods: In this study, rats (n = 48) were divided into 4 groups, i.e. sham-operated, SO-treated sham-operated, 6-OHDA-lesioned and MO-treated lesioned groups. The experimental model of PD was induced by unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA, 12.5 mg/5ml of saline-ascorbate; left side). The treated sham and lesioned groups received MO at a dose of 100 mg/kg once a day before surgery for three times at an interval of 24 h. One week post-surgery, the animals were tested for rotational behavior by apomorphine for an hour and the number of dopaminergic neurons in the substantia nigra pars compacta (SNC) was counted. Results: MO pretreatment significantly improved apomorphine-induced turning behavior and partially prevented loss of SNC neurons with no significant effect on the Sham group. Conclusion: These results suggest that MO pretreatment could exert neuroprotection against 6-OHDA neurotoxicity, as observed by preservation of dopaminergic neurons and attenuation of motor asymmetry and this may have potential benefit in neurodegenerative and movement disorders like PD.