TY - JOUR
T1 - Prolonged maintenance of capsaicin-induced hyperalgesia by brief daily vibration stimuli
AU - Kim, Hee Kee
AU - Schattschneider, Jörn
AU - Lee, Inhyung
AU - Chung, Kyungsoon
AU - Baron, Ralf
AU - Chung, Jin Mo
N1 - Funding Information:
This work was supported by NIH Grants R01 NS31680, AT01474, and P01 NS11255. J.S. was a visiting scholar supported by the Novartis Foundation, and also partially by (1) the Deutsche Forschungsgemeinschaft (DFG Ba 1921/1–3), (2) the German Research Network on “Neuropathic Pain” of the German Ministry of Research and Education (BMBF, 01EM0/1/04), and (3) an unrestricted educational grant from Pfizer, Germany. We express our gratitude to Ms. Denise Broker for her excellent assistance in editing the manuscript.
PY - 2007/5
Y1 - 2007/5
N2 - This study tests the hypothesis that central sensitization initiated by nociceptive input can be maintained by repeated brief innocuous peripheral inputs. Capsaicin was injected intradermally into the hind paw of adult rats. Three different types of daily cutaneous mechanical stimulations (vibration, soft brush, or pressure) were applied to the capsaicin-injected paw for a period of 2 weeks. Daily stimulation consisted of a 10-s stimulation repeated every 30 s for 30 min. Foot withdrawal thresholds to von Frey stimuli applied to the paw were measured once a day for 4 weeks. The capsaicin-only group (control rats without daily stimulation) showed hyperalgesia lasting for 3 days. In contrast, hyperalgesia persisted for 2 weeks in the group that received vibration stimulation. Neither the soft brush nor the pressure group showed a significant difference in mechanical threshold from the control group (capsaicin only). The vibration-induced prolonged hyperalgesia was significantly reduced by systemic injection of ifenprodil, an NMDA-receptor antagonist, but it was not influenced by either an AMPA-receptor blocker or a reactive oxygen species (ROS) scavenger. Furthermore, a dorsal column lesion did not interfere with the prolongation of hyperalgesia. Data suggest that vibration-induced prolongation of hyperalgesia is mediated by spinal NMDA-receptors, and a similar mechanism may underlie some forms of chronic pain with no obvious causes, such as complex regional pain syndrome type 1 (CRPS-1).
AB - This study tests the hypothesis that central sensitization initiated by nociceptive input can be maintained by repeated brief innocuous peripheral inputs. Capsaicin was injected intradermally into the hind paw of adult rats. Three different types of daily cutaneous mechanical stimulations (vibration, soft brush, or pressure) were applied to the capsaicin-injected paw for a period of 2 weeks. Daily stimulation consisted of a 10-s stimulation repeated every 30 s for 30 min. Foot withdrawal thresholds to von Frey stimuli applied to the paw were measured once a day for 4 weeks. The capsaicin-only group (control rats without daily stimulation) showed hyperalgesia lasting for 3 days. In contrast, hyperalgesia persisted for 2 weeks in the group that received vibration stimulation. Neither the soft brush nor the pressure group showed a significant difference in mechanical threshold from the control group (capsaicin only). The vibration-induced prolonged hyperalgesia was significantly reduced by systemic injection of ifenprodil, an NMDA-receptor antagonist, but it was not influenced by either an AMPA-receptor blocker or a reactive oxygen species (ROS) scavenger. Furthermore, a dorsal column lesion did not interfere with the prolongation of hyperalgesia. Data suggest that vibration-induced prolongation of hyperalgesia is mediated by spinal NMDA-receptors, and a similar mechanism may underlie some forms of chronic pain with no obvious causes, such as complex regional pain syndrome type 1 (CRPS-1).
KW - CRPS-1
KW - Capsaicin
KW - Central sensitization
KW - Chronic pain
KW - Hyperalgesia
KW - NMDA-receptor
KW - Persistent pain
KW - Vibration stimulation
UR - http://www.scopus.com/inward/record.url?scp=34047256417&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34047256417&partnerID=8YFLogxK
U2 - 10.1016/j.pain.2006.09.036
DO - 10.1016/j.pain.2006.09.036
M3 - Article
C2 - 17134833
AN - SCOPUS:34047256417
SN - 0304-3959
VL - 129
SP - 93
EP - 101
JO - Pain
JF - Pain
IS - 1-2
ER -