Impaired Nociception and Pain Sensation in Mice Lacking the Capsaicin Receptor
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H. L. Fields Pain (McGraw-Hill New York 1987).
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R. Dubner D. D. Price R. E. Beitel J. W. Hu in Pain in the Trigeminal Region D. J. Anderson and B. Matthews Eds. (Elsevier Amsterdam 1977) pp. 57–66.
S. N. Raja R. A. Meyer M. Ringkamp J. N. Campbell in Textbook of Pain P. D. Wall and R. Melzack Eds. (Churchill Livingstone Edinburgh 1999) pp. 11–55.
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The VR1 gene was disrupted in JM1 mouse embryonic stem cells [
]. See (58) for details of VR1-null mouse generation and northern blot analysis. All animal experiments were subject to institutional review and conducted in accordance with institutional guidelines.
The 100-kb VR1 genomic bacterial artificial chromosome clone was used as a fluorescence in situ hybridization probe on metaphase 129SV/J fibroblasts and mapped by comparison with centromere and telomere positions (Genome Systems St. Louis MO).
Immunohistochemistry was performed as described (7 38) with modifications. See (58) for details on immunohistochemistry and statistical analyses.
Calcium imaging studies were performed on cultured dorsal root ganglion neurons as described (5 29) with modifications. See (58) for details.
M. J. Caterina et al. data not shown.
See (58) for details on patch-clamp analysis of cultured sensory neurons.
Single cutaneous primary afferent neurons were recorded as described (54) [
]. See (58) for details.
Nociceptor conduction velocities were as follows. C fibers: VR1 +/+ 0.56 ± 0.02; VR1 −/− 0.58 ± 0.03; Aδ fibers: VR1 +/+ 5.2 ± 1.5; VR1 −/− 6.4 ± 1.2 m/s.
Behavioral assays were performed as described (40 59) with modifications. See (58) for details.
Some residual paw swelling was observed with high doses (>1 μg) of capsaicin. This could in principle indicate the existence of a resiniferatoxin-insensitive low-affinity capsaicin receptor but more likely reflects receptor-independent membrane perturbation effects similar to those previously reported with high-dose capsaicin [
]. Indeed no significant swelling was seen with similarly effective concentrations of resiniferatoxin.
Individually housed adult mice fed ad libitum were fluid-restricted to a 3-hour test period per day. Fluid intake was monitored by weighing sipper bottles (Nalgene Rochester NY) containing the indicated solutions before and after the test period.
Body temperature and locomotor activity were continuously monitored with intraperitoneal telemetric probes and VitaView Software (MiniMitter Sun River OR). One week after probe implantation animals were injected subcutaneously on the back with capsaicin (1 mg/kg in 0.5 ml of 10% ethanol) or 10% ethanol alone.
Median (and quartile range; qr) mechanical von Frey hair thresholds were as follows. C fibers: VR1 +/+ 8.0 qr 12.0; VR1 −/− 8.0 qr 8.0; Aδ fibers: VR1 +/+ 5.6 qr 4.0; VR1 −/− 8.0 qr 8.0 mN.
See (58) for details on spinal cord recording.
See (58) for details on analysis of heat-evoked spinal cord Fos immunoreactivity.
H. O. Handwerker and P. W. Reeh in Proceedings of the VIth World Congress on Pain M. R. Bond J. E. Charlton C. J. Woolf Eds. (Elsevier Amsterdam 1991) pp. 59–70.
J. Levine and Y. Taiwo in Textbook of Pain P. D. Wall and R. Melzack Eds. (Churchill Livingstone Edinburgh 1994) pp. 45–56.
Mustard oil (10% in mineral oil) was painted on both hind paws and the hot plate assay was performed several minutes later.
CFA and nerve injury experiments were performed as described (38 59) with modifications. See (58) for details.
W. J. Martin and A. I. Basbaum unpublished observation.
For supplemental data see www.sciencemag.org/feature/data/1048712.shl.
We thank members of the Dallman lab for experimental advice and assistance and J. Poblete L. Sun G. Gerkoff K. Schmidt N. Kileen and J. Meneses for expert technical advice and assistance. This work was supported by American Cancer Society and National Alliance for Research on Schizophrenia and Depression postdoctoral fellowships (M.J.C.) by NIH postdoctoral training grant NS07265 (W.J.M.) and by grants from Deutsche Forschungsgemeinschaft (SFB 353; M.K.) the National Institute of Neurological Disorders and Stroke National Institute of Dental and Craniofacial Research and the National Institute of Mental Health (D.J. and A.I.B.) and the Sandler Family Supporting Foundation (D.J.).