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. 2021 Feb 8;10:e65156. doi: 10.7554/eLife.65156

Figure 3. Inhibition of PrL-P neurons unmasks hypersensitivity in neuropathic rats.

(A) Experimental timeline. (B) Tibial nerve transection (TNT) was used to produce the neuropathic injury. (C)- Sensory testing was conducted at 30 min after systemic delivery of CNO and (D) testing was conducted on the lateral plantar surface of the hindpaw in a receptive field adjacent to injured tibial nerve. (E) In TNTPrL.ChR2:hM4Di rats, CNO (2.5 mg·kg−1 i.p.) reduced the mechanical withdrawal threshold at 3 and 7 days post nerve injury on the ipsilateral (injured) hindpaw (two-way ANOVA, main effect CNO, F(1,30)=20.09, p=0.0001; timexCNO, F(2, 60)=6.892, p=0.002; Sidak’s post-test day 3, p=0.008; day 7, p=0.001, n = 16) and (F) on the contralateral paw at 3 days post-injury (two-way ANOVA, CNO F(1,30)=5.77, p=0.02; Sidak’s post-test, p=0.02, n = 16). (G and H) In TNTPrL.Control rats, the same dose of CNO did not alter mechanical withdrawal thresholds on either the ipsilateral or contralateral hindpaw (two-way ANOVA, main effect; ipsilateral CNO, F(1,14)=0.02, p=0.90, n=8 and contralateral CNO, F(1,14)=0.15, p=0.71, n=8, respectively). (I and J) In TNTPrL.ChR2:hM4Di rats, CNO increased acetone-evoked nocifensive events at 3 days post-injury on the ipsilateral paw (two-way ANOVA, main effect CNO, F(1,30)=9.6, p=0.004; Sidak’s post-test, p=0.003, n=16) but not contralaterally (two-way ANOVA, main effect CNO, F(1,29)=1.3, p=0.26, n=16). (K and I) In TNTPrL.Control rats, CNO did not alter acetone-evoked nocicfensive behaviour (two-way ANOVA, main effect CNO ipsilateral, F(1,12)=0.02, p=0.89, n=7 and main effect CNO contralateral, F(1,12)=2.2, p=0.16, n=7).

Figure 3—source data 1. Numerical data to support graphs in Figure 3.

Figure 3.

Figure 3—figure supplement 1. Chemo-inhibition of PrL-P neurons affects nocicfensive behaviour in early but not late timepoints post-injury in neuropathic animals.

Figure 3—figure supplement 1.

(A) In TNTPrL.ChR2:hM4Di rats, systemic delivery of CNO (2.5 mg·kg−1 i.p.) significantly reduced the mechanical withdrawal threshold at 3 and 7 days post-injury on the ipsilateral (injured) hindpaw (mixed model [REML], fixed effects CNO, F(1,28)=7.26, p=0.002; timexCNO, F(5,95)=4.92, p=0.0005; Sidak’s post-test, *p<0.05, n=16). (B) In TNTPrL.ChR2:hM4Di rats, systemic delivery of CNO (2.5 mg·kg−1 i.p.) significantly increased the cold (acetone)-evoked nocicfensive events at 3 days post-injury on the ipsilateral (injured) hindpaw (mixed model [REML], fixed effects CNO, F(1,30)=6.3, p=0.02; timexCNO, F(5,98)=0.6, p=0.70; Sidak’s post-test, ***p=0.0006, n=16).
Figure 3—figure supplement 1—source data 1. Numerical data to support graphs in Figure 3—figure supplement 1.
Figure 3—figure supplement 2. Delivery of vehicle does not affect sensitisation in TNTPrL.ChR2:hM4Di rats at 7 days post-TNT.

Figure 3—figure supplement 2.

Delivery of vehicle (sterile saline with 5% DMSO, i.p.) didnot alter mechanical withdrawal thresholds (paired t-test, t=0.4, n=3) (A) or cold-evoked nocicfensive behaviour (paired t-test, t=0.86, (B) in TNTPrL.ChR2:hM4Di rats [n = 3]).
Figure 3—figure supplement 2—source data 1. Numerical data to support graphs in Figure 3—figure supplement 2.