Unexpected neuronal protection of SU5416 against 1-Methyl-4-phenylpyridinium ion-induced toxicity via inhibiting neuronal nitric oxide synthase

PLoS One. 2012;7(9):e46253. doi: 10.1371/journal.pone.0046253. Epub 2012 Sep 25.

Abstract

SU5416 was originally designed as a potent and selective inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2) for cancer therapy. In this study, we have found for the first time that SU5416 unexpectedly prevented 1-methyl-4-phenylpyridinium ion (MPP(+))-induced neuronal apoptosis in cerebellar granule neurons, and decreased 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced loss of dopaminergic neurons and impairment of swimming behavior in zebrafish in a concentration-dependent manner. However, VEGFR-2 kinase inhibitor II, another specific VEGFR-2 inhibitor, failed to reverse neurotoxicity at the concentration exhibiting anti-angiogenic activity, strongly suggesting that the neuroprotective effect of SU5416 is independent from its anti-angiogenic action. SU5416 potently reversed MPP(+)-increased intracellular nitric oxide level with an efficacy similar to 7-nitroindazole, a specific neuronal nitric oxide synthase (nNOS) inhibitor. Western blotting analysis showed that SU5416 reduced the elevation of nNOS protein expression induced by MPP(+). Furthermore, SU5416 directly inhibited the enzyme activity of rat cerebellum nNOS with an IC(50) value of 22.7 µM. In addition, knock-down of nNOS expression using short hairpin RNA (shRNA) abolished the neuroprotective effects of SU5416 against MPP(+)-induced neuronal loss. Our results strongly demonstrate that SU5416 might exert its unexpected neuroprotective effects by concurrently reducing nNOS protein expression and directly inhibiting nNOS enzyme activity. In view of the capability of SU5416 to cross the blood-brain barrier and the safety for human use, our findings further indicate that SU5416 might be a novel drug candidate for neurodegenerative disorders, particularly those associated with NO-mediated neurotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / pharmacology
  • 1-Methyl-4-phenylpyridinium / pharmacology*
  • Animals
  • Blotting, Western
  • Cells, Cultured
  • Indoles / pharmacology*
  • Neurons / drug effects*
  • Neurons / enzymology*
  • Nitric Oxide Synthase Type I / genetics
  • Nitric Oxide Synthase Type I / metabolism*
  • PC12 Cells
  • Pyrroles / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Zebrafish

Substances

  • Indoles
  • Pyrroles
  • Semaxinib
  • 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine
  • Nitric Oxide Synthase Type I
  • 1-Methyl-4-phenylpyridinium

Grant support

This work was supported by grants from the Research Grants Council of Hong Kong (PolyU5609/09M and 5610/11M), The Hong Kong Polytechnic University (G-U952) and the Shenzhen Shuangbai Funding Scheme 2008; the Science and Technology Development Fund (FDCT) of Macao SAR (045/2007/A3) and the Research Committee of the University of Macau (UL017/09-Y1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.