The effects of aqueous cinnamon bark extract and cinnamaldehyde on neurons of substantia nigra and behavioral impairment in a mouse model of Parkinson’s disease

Background and Objective: Parkinson's disease (PD) is characterized by a progressive loss of dopaminergic neurons in substantia nigra. In recent years, there have been interests in the role of the free radical damage in PD. Cinnamon and its derivative, cinnamaldehyde acts as powerful antioxidant and anti-inflammatory agents. This research focused on the effects of cinnamon extract and cinnamaldehyde on neurons of SNc of a mouse model of Parkinson’s disease. Materials and Methods: 45 adult male mice with an average weight of 25-35 g were divided into 9 groups of 5 each: group 1: control PBS, group 2: control serum, group 3: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), group 4: MPTP + low dose of cinnamon extract pretreatment (20 mg/kg), group 5: MPTP+ high dose of cinnamon extract pretreatment (40 mg/kg), group 6: MPTP + low dose of cinnamon extract treatment (20 mg/kg), group7: MPTP + high dose of cinnamon extract treatment (40 mg/kg), group 8: MPTP + cinnamaldehyde pretreatment (30 mg/kg), group 9: MPTP+ cinnamaldehyde treatment (30 mg/kg). Rotarod test was used to assess motor and balance of the mice. After behavioral studies, all mice were anesthetized and perfused transcardially with 0.1 M PBS (PH=7.4) followed by 4% buffered paraformaldehyde fixative. The brain of the mice were removed and fixed in the paraformaldehyde and stained for Nissl and the number of Nissl-stained neurons were counted. Data was analyzed using SPSS software by one way ANOVA. Results: Aqueous cinnamon extract and cinnamaldehyde improved rotarod performance of MPTP-lesioned mice and prevented loss of Nissl-stained neurons of SNc of the midbrain. Conclusion: These findings suggest that cinnamaldehye as a natural antioxidant may protect  neurons of SNc neurons against Parkinson’s disease.