High expression of nicotamide N-methyltransferase in patients with idiopathic Parkinson's disease

Richard Parsons, SW Smith, Rosemary Waring, Adrian Williams, David Ramsden

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62 Citations (Scopus)


We have previously speculated that elevated levels of nicotinamide N-methyltransferase (NNMT), the primary catabolic enzyme of nicotinamide. may result in reduced Complex I activity in idiopathic Parkinson's disease (IPD) in two ways: (1) reduction in the levels of nicotinamide available for nicotinamide adenine dinucleotide synthesis; and (2) increased methylation of compounds such as tetrahydroisoquinolines and beta-carbolines, which are potent Complex I inhibitors. Expression of NNMT was assessed in 91 cerebella (53 IPD. 38 control) using immunohistochemistry coupled with quantitative digital image analysis. Control cerebella showed a distribution of expression ascribed to low, intermediate and high expressors with ratios of 1:2:1 categories. Expression in the parkinsonian cerebella was significantly higher than in the control group (control group median expression 17%, mean expression 16.6%, range 0-51%, standard deviation 11.4%. standard error 1.9%; IPD group median expression 46%, mean expression 53.7%, range 21-100%, standard deviation 23.4%, standard error 3.2%: P <0.0001; unpaired t-test with Welch correction (parametric) and Mann-Whitney U-test (non-parametric)). These results confirm that NNMT expression is elevated in IPD, which may ultimately lead to neurodegeneration via a reduction in Complex I activity. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)13-16
Number of pages4
JournalNeuroscience Letters
Issue number1-2
Publication statusPublished - 1 Jan 2003


  • 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine
  • Parkinson's disease
  • nicotinamide adenine dinucleotide
  • complex 1
  • nicotinamide N-methyltransferase
  • neurodegeneration
  • cerebella


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