Effect of intrathecal cell-penetrating peptide Tat-FynP on inflammatory pain in rats

Abstract

Objective To evaluate the effect of intrathecal cell-penetrating peptide Tat-FynP on inflammatory pain in rats. Methods Eighty healthy male Sprague-Dawley rats, aged 6-8 weeks, weighing 180-220 g, were randomly divided into 5 groups(n=16 each)using a random number table: control group(group C), inflammatory pain group(group IP), group FynP, group Tat-FynP and group mTat-FynP.Inflammatory pain was induced by injecting complete Freund′s adjuvant 100 μl into the plantar surface of the right hindpaw in IP, FynP, Tat-FynP, and mTat-FynP groups, while the equal volume of normal saline was given in group C. At 1 day after establishment of the model, FynP, Tat-FynP and mTat-FynP 15 μl(20 μg/kg)were injected intrathecally in FynP, Tat-FynP, and mTat-FynP groups, respectively.Ten rats in each group were randomly selected, and the mechanical paw withdrawal threshold(MWT)and thermal paw withdrawal latency(TWL)were measured before establishment of the model and at 1, 3, 5, 7, 10 and 14 days after establishment of the model.The left 6 rats were selected from each group at 1 day after intrathecal administration, and the lumbar enlargement segments of the spinal cord were removed for determination of phosphorylated 2B subunit-containing NMDA receptor(p-NR2B)expression by Western blot. Results Compared with group C, the MWT was significantly decreased, and the TWL was significantly shortened at each time point after establishment of the model, and the expression of p-NR2B was significantly up-regulated in IP, FynP, Tat-FynP and mTat-FynP groups(P 0.05). Conclusion Intrathecal cell-penetrating peptide Tat-FynP can reduce inflammatory pain in rats. Key words: Cell-penetrating peptides; Injections, spinal; Inflammation; Pain