title: Lumbar sympathectomy attenuates cold allodynia but not mechanical allodynia and hyperalgesia in rats with spared nerve injury.
abstract: In certain patients with neuropathic pain, the pain is dependent on activity in the sympathetic nervous system. To investigate whether the spared nerve injury model (SNI) produced by injury to the tibial and common peroneal nerves and leaving the sural nerve intact is a model for sympathetically maintained pain, we measured the effects of surgical sympathectomy on the resulting mechanical allodynia, mechanical hyperalgesia, and cold allodynia. Decreases of paw withdrawal thresholds to von Frey filament stimuli and increases in duration of paw withdrawal to pinprick or acetone stimuli were observed in the ipsilateral paw after SNI, compared with their pre-SNI baselines. Compared with sham surgery, surgical lumbar sympathectomy had no effect on the mechanical allodynia and mechanical hyperalgesia induced by SNI. However, the sympathectomy significantly attenuated the cold allodynia induced by SNI. These results suggest that the allodynia and hyperalgesia to mechanical stimuli in the SNI model is not sympathetically maintained. However, the sympathetic nervous system may be involved, in part, in the mechanisms of cold allodynia in the SNI model.
  
  
  CONCLUSIONS
  The results of our study suggest that the SNI model is not an appropriate model of sympathetically maintained mechanical allodynia and hyperalgesia but may be useful to study the mechanisms of cold allodynia associated with sympathetically maintained pain states.
authors: Department of Anesthesiology and Critical Care Medicine, Baltimore, Maryland, USA.
authors: Chengshui
authors: C
authors: Zhao
authors: Lun
authors: L
authors: Chen
authors: Yuan-Xiang
authors: YX
authors: Tao
authors: Jill M
authors: JM
authors: Tall
authors: Jasenka
authors: J
authors: Borzan
authors: Matthias
authors: M
authors: Ringkamp
authors: Richard A
authors: RA
authors: Meyer
authors: Srinivasa N
authors: SN
authors: Raja
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000473:pathology; D003080:Cold Temperature / Q000009:adverse effects*; D004195:Disease Models, Animal; D006038:Glyoxylates; D006930:Hyperalgesia / Q000209:etiology / Q000601:surgery*; D008297:Male; D009412:Nerve Fibers / Q000473:pathology; D010146:Pain / Q000209:etiology / Q000601:surgery*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020426:Sciatic Neuropathy / Q000150:complications / Q000473:pathology / Q000601:surgery*; D013562:Sympathectomy / Q000379:methods*; D013997:Time Factors
chemical_list: D006038:Glyoxylates; C031150:glyoxylic acid