Abstract
We report that GTP cyclohydrolase (GCH1), the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis, is a key modulator of peripheral neuropathic and inflammatory pain. BH4 is an essential cofactor for catecholamine, serotonin and nitric oxide production. After axonal injury, concentrations of BH4 rose in primary sensory neurons, owing to upregulation of GCH1. After peripheral inflammation, BH4 also increased in dorsal root ganglia (DRGs), owing to enhanced GCH1 enzyme activity. Inhibiting this de novo BH4 synthesis in rats attenuated neuropathic and inflammatory pain and prevented nerve injury-evoked excess nitric oxide production in the DRG, whereas administering BH4 intrathecally exacerbated pain. In humans, a haplotype of the GCH1 gene (population frequency 15.4%) was significantly associated with less pain following diskectomy for persistent radicular low back pain. Healthy individuals homozygous for this haplotype exhibited reduced experimental pain sensitivity, and forskolin-stimulated immortalized leukocytes from haplotype carriers upregulated GCH1 less than did controls. BH4 is therefore an intrinsic regulator of pain sensitivity and chronicity, and the GTP cyclohydrolase haplotype is a marker for these traits.
Original language | English |
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Pages (from-to) | 1269-1277 |
Number of pages | 9 |
Journal | Nature Medicine |
Volume | 12 |
Issue number | 11 |
DOIs | |
State | Published - Nov 2006 |
Externally published | Yes |
Bibliographical note
Funding Information:We acknowledge R. Keller, co-principal investigator of the Maine Lumbar Spine Study, for his support and advice; A. Häussler, P. Kahler, I.N. Grundei, A. Kirchhof, A. Bollettino, H. Hipp and C. McKnight for technical assistance; S. Niemann and A. Kingman for genetic and biostatistical advice; E.R. Werner for biochemical advice and C. Hesslinger (Pharmazentrum Frankfurt, J.W. Goethe-University, Frankfurt, Germany; current affiliation: ALTANA Pharma AG, Konstanz, Germany) for the GTP cyclohydrolase antibody. The work was supported by grants from the US National Institutes of Health (NS039518 and NS038253, C.J.W.; NS052623, M.C.; Z01 DE00366, M.B.M.; Z01 AA000301, D.G.; DE16558, DE07509 and NS045685, L.D. and W.M.), the Deutsche Forschungsgemeinschaft (DFG322_2-1, S.F.B.; 553/C6, I.T. and G.G.), the Bundesministerium für Bildung und Forschung (BMBF 01, E.M.; 0511, G.G.) and the Dr. Robert Pfleger Foundation (I.T.).