Correlation of intact sensibility and neuropathic pain-related behaviors in eight inbred and outbred rat strains and selection lines

In some rat strains, total hindpaw denervation triggers autotomy, a behavio r of self mutilation presumably related to neuropathic pain. Partial sciati c ligation (PSL) in rats produces tactile allodynia and heat hyperalgesia b ut not autotomy. Our aims in this study were to examine: (1) whether sensib ility of intact rats to noxious and non-noxious stimuli is strain-dependent ; (2) whether sensibility of intact rats could predict levels of autotomy, or of allodynia and hyperalgesia in the PSL model; and (3) whether autotomy levels are correlated with levels of allodynia or hyperalgesia. Here we re port that in two inbred rat strains (Lewis and Fisher 344), two outbred rat strains (Sabra and Sprague-Dawley) and four selection lines of rats (Genet ically Epilepsy-Prone Rats, High Autotomy, Low Autotomy and Flinders Sensit ive Line), tactile sensitivity and response duration to noxious heat of int act animals were strain-dependent. Levels of autotomy following hindpaw den ervation and of allodynia and hyperalgesia in the PSL model were also strai n-dependent. Thus, these traits are determined in part by genetic factors. Sensory sensibility of intact rats was not correlated with levels of autoto my following total denervation, or allodynia and hyperalgesia following par tial denervation. We suggest that preoperative sensibility of intact rats i s not a predictor of levels of neuropathic disorders following nerve injury . Likewise, no correlation was found between autotomy, allodynia and hypera lgesia, suggesting that neuropathic pain behaviors triggered by nerve injur y of different etiologies are mediated by differing mechanisms. (C) 2001 In ternational Association for the Study of Pain. Published by Elsevier Scienc e B.V. All rights reserved.