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. 2022 Nov 11;25(12):105555. doi: 10.1016/j.isci.2022.105555

Figure 2.

Figure 2

PNI-induced tactile allodynia is mediated via NMDA receptors

To analyze only NMDA receptor-mediated responses, the RF was stimulated under bicuculine (GABA receptor antagonist; 20 μM), strychnine (glycine receptor antagonist; 2 μM), CNQX (AMPA receptor antagonist; 20 μM) perfusion. Consequently, all responses were abolished under AP5 (NMDA receptor antagonist; 50 μM) perfusion.

(A–C) Representative chart recordings under antagonist administration in Sham, CCI-E, and CCI-L rats, respectively.

(D) Comparison of touch-evoked AUCs via only NMDAR between Sham, CCI-E, and CCI-L rats and confirmation of the loss of NMDAR-mediated responses by AP5 perfusion. In Sham rats, touch-evoked AUC via only NMDAR was almost not observed, whereas it was significantly increased in CCI-L rats. AUC - Sham: 0.11 ± 0.08 × 105 ΔpA/5 s; CCI-E: 1.09 ± 0.30 × 105 ΔpA/5 s, p = 0.055; CCI-L: 1.23 ± 0.34 × 105 ΔpA/5 s, †p = 0.0235. NMDAR-mediated evoked EPSCs were abolished by AP5 perfusion. AUC - CCI-E post-AP5: 0.041 ± 0.017 × 105 ΔpA/5 s, ∗p = 0.0221 (versus CCI-E pre AP5); CCI-L post-AP5: 0.042 ± 0.020 × 105 ΔpA/5 s, ∗p = 0.0410 (versus CCI-L pre AP5).

(E) NMDAR-mediated pinch-induced AUC was almost not observed in either Sham, CCI-E, or CCI-L rats. Pinch-induced AUC was not altered by AP5 administration. AUC - Sham: 0.04 ± 0.02 × 105 ΔpA/5 s; CCI-E: 0.22 ± 0.13 × 105 ΔpA/5 s, p = 0.4653; CCI-L: 0.26 ± 0.15 × 105 ΔpA/5 s, p = 0.3351. NMDAR-mediated evoked EPSCs were abolished by AP5 perfusion. AUC - CCI-E post-AP5: 0.071 ± 0.052 × 105 ΔpA/5 s, p = 0.3896 (versus CCI-E pre AP5); CCI-L post-AP5: 0.038 ± 0.024 × 105 ΔpA/5 s, p = 0.2245 (versus CCI-L pre AP5). Significant differences were assessed using the one-way ANOVA and two-sided unpaired Student’s t test. n.s., not significant.