Fig. 8

Inhibition of PI3K/Akt pathway activity, which is regulated by GLP-1R, prevented NTG-induced allodynia. a-c Representative immunoblots of PI3K and p-Akt (Ser473) in the TNC on different days following NTG injection. The band intensities of PI3K and p-Akt are presented relative to those of β-actin and total Akt, respectively. Quantitative analysis revealed a dramatic increase on day 9 after NTG administration. Data are presented as mean ± SEM; n = 6/group; *p < 0.05 vs. sham group. d-f Representative western blots showing the changes in PI3K and p-Akt (Ser473) protein expression in the TNC after liraglutide and exendin(9–39) treatment. The results showed that activation of GLP-1R by liraglutide markedly suppressed the increase in PI3K and p-Akt in the TNC in CM mice. Data are presented as mean ± SEM; n = 6/group; ***p < 0.001 vs. the sham group; ^##p < 0.01, ^###p < 0.001 vs. the CM group. Repeated treatment with the PI3K selective inhibitor LY294002 partially attenuated CM-associated basal periorbital (g) and hindpaw (i) mechanical hyperalgesia. Post-treatment responses, including periorbital (h) and hindpaw (j) mechanical allodynia, were assessed 2 h following NTG injection; however, LY294002 had no significant effect on NTG-induced acute allodynia. Data are presented as mean ± SEM; n = 8/group; two-way ANOVA and Bonferroni post hoc analysis; *^,$p < 0.05, ^**,$$p < 0.01 and ***p < 0.001 The CM and CM + LY294002 groups vs. the sham group; ^#p < 0.05 and ^##p < 0.01 vs. the CM group