Neuroprotective effect of epigallocatechin gallate in an experimental model of Parkinson’s disease induced by 6-hydroxydopamine

Background and Objective: Parkinson's disease is a common movement disorder in elders caused by depletion of dopaminergic neurons in the substantia nigra in midbrain. Due to antioxidant and neuroprotective properties of epigallocatechin gallate (EGCG), the present study investigated its neuroprotective effect in an experimental model of Parkinson's disease.

Materials and Methods: In this experimental study, male rats (n=32) were divided into 4 groups: sham, EGCG-treated sham, EGCG-treated lesion and lesion groups. Model of Parkinson's disease was induced by injecting 12.5 microgram of 6-hydroxydopamine- ascorbate dissolved in saline solution into the left side of neostriatum. In EGCG-treated sham and EGCG-treated lesion groups, 20 mg/kg of EGCG was administered intraperitonealy two times with an interval of 24 hours before steriotoxic surgery. After 1 week, the rotational behavior following apomorphine injections was assessed in one hour and dopaminergic neurons in substantia nigra were counted.

Results: In the lesion group, apomorphine caused contralateral rotational behavior (p < 0.001) and the number of neurons in left substantia nigra was significantly reduced in comparison with sham group (p < 0.05). Administration of EGCG in lesion group significantly reduced the number of apomorphine -induced rotations (p < 0.05), however it had no effect on the number of neurons in the substantia nigra.

Conclusion: Pre-treatment with intraperitoneal administration of EGCG can reduce the motor asymmetry (attenuation of rotational behavior) in the experimental model of Parkinson's disease but it does not have a significant protective effect on toxicity of 6-hydroxydopamine.