Selegiline is a monoamine oxidase-B (MAO-B) inhibitor with anti-Parkinsonian effects, but it is metabolized to amphetamines. Since another MAO-B inhibitor N-Methyl, N-propynyl-2-phenylethylamine (MPPE) is not metabolized to amphetamines, we examined whether MPPE induces behavioral side effects and whether MPPE affects dopaminergic toxicity induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Multiple doses of MPPE (2.5 and 5 mg/kg/day) did not show any significant locomotor activity and conditioned place preference, whereas selegiline (2.5 and 5 mg/kg/day) significantly increased these behavioral side effects. Treatment with MPPE resulted in significant attenuations against decreases in mitochondrial complex I activity, mitochondrial Mn-SOD activity, and expression induced by MPTP in the striatum of mice. Consistently, MPPE significantly attenuated MPTP-induced oxidative stress and MPPE-mediated antioxidant activity appeared to be more pronounced in mitochondrial-fraction than in cytosolic-fraction. Because MPTP promoted mitochondrial p53 translocation and p53/Bcl-xL interaction, it was also examined whether mitochondrial p53 inhibitor pifithrin-μ attenuates MPTP neurotoxicity. MPPE, selegiline, or pifithrin-μ significantly attenuated mitochondrial p53/Bcl-xL interaction, impaired mitochondrial transmembrane potential, cytosolic cytochrome c release, and cleaved caspase-3 in wild-type mice. Subsequently, these compounds significantly ameliorated MPTP-induced motor impairments. Neuroprotective effects of MPPE appeared to be more prominent than those of selegiline. MPPE or selegiline did not show any additional protective effects against the attenuation by p53 gene knockout, suggesting that p53 gene is a critical target for these compounds. Our results suggest that MPPE possesses anti-Parkinsonian potentials with guaranteed behavioral safety and that the underlying mechanism of MPPE requires inhibition of mitochondrial oxidative stress, mitochondrial translocation of p53, and pro-apoptotic process.
Bibliographical noteFunding Information:
This study was supported by a grant (14182MFDS979) from the Korea Food and Drug Administration and partially by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (no. NRF-2013R1A1A2060894 and no. NRF-2013R1A1A1007378), Republic of Korea, and by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (2011–0018355). Yunsung Nam and The-Vinh Tran were supported by the BK21 PLUS program, National Research Foundation of Korea, Republic of Korea. Equipment at the Institute of New Drug Development Research (Kangwon National University) was used for this study. The English in this document has been checked by at least two professional editors, both native speakers of English ( Beverly Hills English, Los Angeles, CA90024, USA).
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All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience