The effect of aqueous extract of Melissa officinalis on the oxidative stress indices in the midbrain tissue

Parkinson disease (PD) is a common neuropathologic disorder. It is resulted from degeneration of the dopaminergic neurons of the substantia nigra pars compacta. It is known that the increased level of oxidative stress leads to the degeneration of dopaminergic neurons. Due to the antioxidant activities of Melissa officinalis, this study aimed to assess the effect of aqueous extract of Melissa officinalis on the oxidative stress indices of the midbrain. Forty eight male Wistar rats (weighing 250-300 g) were assigned to four groups including control (CON), control treated with the extract (CONE), leasioned (L) and leasioned treated with the extract (LE). The neurodegeneration was induced through the injection of 12.5 µg 6-hydroxydopamine (6-OHDA) in the left striatum. The CONE and LE groups were pretreated by 1 mg/kg/day of water extract of Melissa officinalis. The extract treatment was repeated three times with a 24-hour interval and then the neurodegeneration was induced in the animals. Two weeks after the neurodegeneration, the plasma level of malondealdehyde (MDA), nitrite, and superoxide dismutase (SOD) were measured. Results showed a significant increase in the level of MDA in the L group; pretreatment with the extract considerably declined the plasma concentration of MDA. Moreover, the SOD activity was profoundly lower in the L compared to the CON group. The extract was ineffective on the SOD activity in the LE group. The oral administration of water extract of Melissa officinalis (100 mg/kg) can diminish some stress oxidative inducers in the midbrain.