FIGURE 4.

Piezo2 knockdown prevents NGF-induced sensitization of Aδ bone afferent neurons. (A) Retrograde labeling of bone afferent neurons (FB, blue, arrowheads) revealed that a substantial proportion of neurons that innervate bone express Piezo2 (red, hashes) and the NGF receptor TrkA (green, asterisks). Scale bars = 100 μm. (B) Frequency histogram showing that the majority of medium-sized bone afferent neurons expressed Piezo2, and that most Piezo2 expressing bone afferent neurons also expressed TrkA. (C) A significantly lower proportion of Aδ bone afferent neurons were sensitized (increased discharge frequencies) by NGF in Piezo2 antisense treated animals compared to mismatch control animals [chi-square test, X² (1, N = 32) = 10.86,*P < 0.05, n = 15 mismatch/17 antisense, N = 8 mismatch/9 antisense]. (D) A significantly lower proportion of Aδ bone afferent neurons were sensitized (lower thresholds for activation) by NGF in Piezo2 antisense treated animals compared to mismatch control animals (chi-square test, X² (1, N = 32) = 7.069,*P < 0.05, n = 15 mismatch/17 antisense, N = 8 mismatch/9 antisense).