Dopamine (DA) receptor (D1 and D2-like receptors) agonists are known to affect expression levels of DA receptors. Rotigotine, a DA D2-like receptor agonist, has been developed for treating Parkinson’s disease (PD). However, its role in PD by acting through DA D2-like receptors has not been fully understood yet. The purpose of this study was to investigate neuroprotective effects of rotigotine through DA D2 and D3 receptors in 6-hydroxydopamine (6-OHDA) induced mouse model of PD. Expression level of tyrosine hydroxylase (TH) was examined using immunohistochemistry and Western blot analysis. Results revealed that unilateral injection of 6-OHDA into the midbrain caused significant loss of TH positive cells in the substantia nigra, whereas rotigotine inhibited such loss of TH cells in 6-OHDA-induced mouse model of PD. In vitro experiments demonstrated that rotigotine increased expression levels of TH against 6-OHDA-induced toxicity. The expression level of TH after treatment with L’741,626, a D2 receptor antagonist was decreased more than that after treatment with GR 103691, a D3 receptor antagonist. These results suggest that rotigotine can protect DA neurons against 6-OHDA induced toxicity and that the protective effect of rotigotine for DAergic neurons through a DA D2 receptor is stronger than that through a DA D3 receptor.

Introduction
Materials and Methods
    Animals
    Primary cell culture and drug treatments
    Stereotaxic surgery and drug treatments
    Sample preparation and immunohistochemistry
    Western blot analysis
    Statistics
Results
Discussion
References

• Si-joon Lee(Institute of Animal Medicine & Department of Veterinary Medicine, Gyeongsang National University/Laboratory Animal Center, Daegu Gyeongbuk Medical Innovation Foundation)
• Mun-ki Kim(Institute of Animal Medicine & Department of Veterinary Medicine, Gyeongsang National University)
• Chung-kil Won(Institute of Animal Medicine & Department of Veterinary Medicine, Gyeongsang National University) Corresponding author