J. Clin. Invest. 113:1344-1352 (2004). doi:10.1172/JCI200420449.
Copyright ©2004 by the American Society for Clinical Investigation
Deletion of vanilloid receptor 1_expressing primary afferent neurons for pain control
Laszlo Karai1, Dorothy C. Brown2, Andrew J. Mannes1, Stephen T. Connelly1, Jacob Brown1, Michael Gandal1, Ofer M. Wellisch1, John K. Neubert1, Zoltan Olah1 and Michael J. Iadarola1
1National Institute of Dental and Craniofacial Research, Bethesda, Maryland, USA.
2School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Address correspondence to: Michael J. Iadarola, National Institute of Dental and Craniofacial Research, 49 Convent Drive, Bethesda, Maryland 20892, USA. Phone: (301) 496-2758; Fax: (301) 401-0667; E-mail: miadarola@dir.nidcr.nih.gov.
Received for publication November 3, 2003, and accepted in revised form February 25, 2004.
Control of cancer, neuropathic, and postoperative pain is frequently inadequate or compromised by debilitating side effects. Inhibition or removal of certain nociceptive neurons, while retaining all other sensory modalities and motor function, would represent a new therapeutic approach to control severe pain. The enriched expression of transient receptor potential cation channel, subfamily V, member 1 (TRPV1; also known as the vanilloid receptor, VR1) in nociceptive neurons of the dorsal root and trigeminal ganglia allowed us to test this concept. Administration of the potent TRPV1 agonist resiniferatoxin (RTX) to neuronal perikarya induces calcium cytotoxicity by opening the TRPV1 ion channel and selectively ablates nociceptive neurons. This treatment blocks experimental inflammatory hyperalgesia and neurogenic inflammation in rats and naturally occurring cancer and debilitating arthritic pain in dogs. Sensations of touch, proprioception, and high-threshold mechanosensitive nociception, as well as locomotor function, remained intact in both species. In separate experiments directed at postoperative pain control, subcutaneous administration of RTX transiently disrupted nociceptive nerve endings, yielding reversible analgesia. In human dorsal root ganglion cultures, RTX induced a prolonged increase in intracellular calcium in vanilloid-sensitive neurons, while leaving other, adjacent neurons unaffected. The results suggest that nociceptive neuronal or nerve terminal deletion will be effective and broadly applicable as strategies for pain management. |
