Fig. 5
The effect of chemical sympathectomy with guanethidine on behavioural signs of pain. a 50 % withdrawal threshold to von Frey fibres in the plantar paw of cuff, SNI, and sham rats treated with guanethidine or vehicle 2 weeks after surgery. Cuff animals had significant mechanical allodynia, and this was unaltered by guanethidine. b 50 % withdrawal threshold to von Frey fibres in the plantar paw of cuff, SNI, and sham rats treated with guanethidine or vehicle 6 weeks after surgery. Cuff animals had significant mechanical allodynia which was completely alleviated by guanethidine. c 50 % withdrawal thresholds to von Frey fibres in the lateral paw of SNI, and sham rats treated with guanethidine or vehicle 2 weeks after surgery. SNI animals had significant mechanical allodynia which was partially alleviated by guanethidine. d 50 % withdrawal thresholds to von Frey fibres in the lateral paw of SNI, and sham rats treated with guanethidine or vehicle 6 weeks after surgery. SNI animals had significant mechanical allodynia which was partially alleviated by guanethidine. e Responses to cold plate set to 5 °C in cuff, SNI and sham rats treated with guanethidine or vehicle 2 weeks after surgery. Cuff animals had significant cold hyperalgesia which was unaltered by guanethidine. f Responses to cold plate set to 5 °C in cuff, SNI and sham rats treated with guanethidine or vehicle 6 weeks after surgery. SNI animals had significant cold hyperalgesia which was reduced by guanethidine. Each point represents the mean ± SEM (n = 6–8 per group). B baseline. *p < 0.05, **p < 0.01, ***p < 0.001 compared with baseline, #p < 0.05, ##p < 0.01 compared to vehicle treated rats, by a one way ANOVA with Bonferroni post hoc. g Bar graph showing the mean number of DBH-IR fibres in the upper dermis per 1 mm2 in 6 week cuff and SNI animals after guanethidine or vehicle. *p < 0.05 by t-test