Principal Investigator/Program Director (Last, first, middle): Woolf, Clifford, J RESEARCH &RELATED Other Project Information 1. * Are Human Subjects Involved? m Yes l No 1.a. If YES to Human Subjects Is the IRB review Pending? m Yes m No IRB Approval Date: Exemption Number: 1 2 3 4 5 6 Human Subject Assurance Number 2. * Are Vertebrate Animals Used? l Yes m No 2.a. If YES to Vertebrate Animals Is the IACUC review Pending? m Yes l No IACUC Approval Date: 01-05-2007 Animal Welfare Assurance Number A3596-01 3. * Is proprietary/privileged information m Yes l No included in the application? 4.a.* Does this project have an actual or potential impact on m Yes l No the environment? 4.b. If yes, please explain: 4.c. If this project has an actual or potential impact on the environment, has an exemption been authorized or an environmental assessment (EA) or environmental impact statement (EIS) been performed? m Yes m No 4.d. If yes, please explain: 5.a.* Does this project involve activities outside the U.S. or m Yes l No partnership with International Collaborators? 5.b. If yes, identify countries: 5.c. Optional Explanation: 6. * Project Summary/Abstract 5843-Abstract.pdf Mime Type: application/pdf 7. * Project Narrative 283-relevance.pdf Mime Type: application/pdf 8. Bibliography &References Cited 5887-references.pdf Mime Type: application/pdf 9. Facilities &Other Resources 6389-topresources.pdf Mime Type: application/pdf 10. Equipment 7623-finalequipment.pdf Mime Type: application/pdf Tracking Number: Other Information Page 6 OMB Number: 4040-0001 Expiration Date: 04/30/2008 Principal Investigator/Program Director (Last, first, middle): Woolf, Clifford, J Transcripts for two tetrahydrobiopterin (BH4) synthetic enzymes, GTP cyclohydrolase 1 (GCH1) and sepiapterin reductase, and a BH4 recycling enzyme quinoid dihydroypteridine reductase, are upregulated in dorsal root (DRG) neurons after peripheral nerve injury. This induction is associated with an increase in BH4 in the DRG. BH4 is an essential cofactor for the aromatic amine hydroxylases that produce 5- hyrdoxytryptamine, norepinephrine and dopamine, and for all nitric oxide synthases. The nerve injury-induced increase in BH4 is prevented by systemic administration of a GCH1 inhibitor, diamino hydroxypyrimidine (DAHP). DAHP has no analgesic effects in na?ve animals but produces a marked reduction in pain-related behavior in rodents with peripheral nerve lesions and inflammation. Intrathecal BH4 itself produces acute pain hypersensitivity. Using an analysis of single nucleotide polymorphisms we have also identified a haplotype in human GCH1 that is """"""""pain protective"""""""" in patients after surgery for chronic back pain and associated with reduced pain sensitivity in healthy subjects. Based on these data we hypothesize that BH4 contributes to the initiation and maintenance of neuropathic and inflammatory pain.
The aim of this proposal is to: 1. Study where and when BH4 induction occurs in the DRG in pain-related rodent models and what kinds of stimuli are responsible, 2. Characterize the behavioral consequences of deletion, inhibition or overexpression of GCH1 selectively in adult primary sensory neurons, and 3. Identify the mechanisms in sensory neurons by which BH4 produces pain. We will study the time course and cellular localization of changes in the expression and activity of BH4 synthetic and recycling enzymes in the DRG in response to tissue inflammation and partial peripheral nerve injury (Aim 1). To elucidate the specific role of BH4 in sensory neurons we will employ mice that selectively overexpress, or have a deletion of GCH1 in adult primary afferents, as well as mice that overexpress the endogenous inhibitor of GCH1, GFRP, using tamoxifen-inducible DRG neuron-specific Cre-recombinase technology (Aim 2). nNOS is upregulated in association with the increase in BH4 and we will test if BH4 produces pain by producing an increase in NO and calcium influx. We will use primary cultures of DRG neurons to explore the direct action of BH4 on these neurons and the downstream effectors responsible. The proposal is designed to explore the molecular mechanisms responsible for pain and identify novel targets for the development of new analgesics. Project Description Page 7
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