Ablation of NK1 receptor expressing neurones in the dorsal horn reduces SNI induced decrease in mechanical threshold and ERK phosphorylation in the RVM. Effect of SSP-SAP or saline intrathecal injections on: A/mechanical threshold following SNI surgery measured by Von Frey testing and B/SNI induced pERK expression in the RVM 8 days after SNI surgery. SSP-SAP treatment significantly attenuated both the SNI induced hyperalgesia and the SNI induced ERK activation in the RVM. N = 3-5 in each group. Data show mean ± SEM. * P < 0.05, ** P < 0.01.