Bilateral Neuropathy of Primary Sensory Neurons by the Chronic Compression of Multiple Unilateral DRGs
Behaviors of spontaneous pain, mechanical allodynia, and hyperalgesia recorded in mCCD rats. (a) The increase of the number of “wet-dog shaking” (WDS) behaviors at different time points after the mCCD (RM ANOVA, ). (b) The increase of the number of shrinking bilateral hind paws at different time points after the mCCD (RM ANOVA, ). (c) Hind paw withdrawal thresholds were markedly decreased bilaterally after the chronic compression () compared to those of control () and sham groups () (on 10th postoperative day, one-way ANOVA followed by Bonferroni tests, compared to those of control group, compared to those of sham group). (d) Stimulus response curves of ipsilateral and contralateral hind paws to von Frey filaments. Following the chronic compression of multiple DRGs (), the stimulus response curves of both hind paws were markedly shifted to the left compared to those of the control group () (general line model, all ), and there was an obvious significant increase in the response frequency to 2.0 and 6.0 g von Frey filaments (nonnoxious mechanical stimuli) of both the ipsilateral and contralateral sides (Bonferroni test, ). There was also a significant increase in the response to 8.0 and 10.0 g von Frey filaments (which were noxious mechanical stimuli) bilaterally (Bonferroni test, ). (e) The time course of ipsilateral and contralateral hind paw mechanical withdrawal thresholds after chronic compression of multiple DRGs (mCCD group: ; control group: ; sham group: ). The ipsilateral hind paw withdrawal thresholds were decreased significantly below baseline on the 1st postoperative day and remained low throughout the entire testing period (RM ANOVA, ). Contralateral mechanical thresholds were similarly decreased to a lesser extent on the 1st postoperative day, reached their lowest peak during the 10th to 14th postoperative day (RM ANOVA, ), and recovered to basal levels thereafter. (f) Bilateral mechanical hypersensitization occurred in bilateral forepaws in the mCCD rat (mCCD group: ; control group: ; RM ANOVA, ).