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. 2021 Dec 27;145(10):3637–3653. doi: 10.1093/brain/awab482

Figure 4.

Figure 4

The genetic loss of Nav1.7 in rodent C-LTMRs results in mechanical hyposensitivity and abnormalities in cooling detection. Acute sensory testing of mice lacking Nav1.7 in the TH-positive C-LTMR population (blue: THCreERT2:Nav1.7-KO) compared with controls (grey: Nav1.7-WT). (A) C-LTMR-specific deletion of Nav1.7 results in significant hyposensitivity to punctate mechanical von Frey stimuli [WT: n = 31 mice, KO: n = 28 mice, two-tailed Student’s unpaired t-test, t(57) = 5.062, P < 0.0001, ***]. (B) The number of responses to a cotton swab or (C) to a brush are not affected by the loss of Nav1.7 in rodent C-LTMRs [WT: n = 19 mice, KO: n = 19 mice, two-tailed Student’s unpaired t-test, t(36) = 0.690, P = 0.49 and t(36) = 1.09, P = 0.28, respectively, n.s]. (D) Mice specifically lacking Nav1.7 in C-LTMRs showed no changes in their latency to withdraw from a noxious 53°C hotplate. [WT: n = 19 mice, KO: n = 19 mice, two-tailed Student’s unpaired t-test, t(36) = 0.470, P = 0.64, n.s]. (E) Mice lacking Nav1.7 in C-LTMRs spent more time in cooler zones during 0–30 min of the thermal gradient test. The non-linear regression Gaussian fitted curves are significantly different between WT and KO mice, with KO mice showing a leftward shift toward colder temperatures [WT: n = 12 mice, KO: n = 9 mice, non-linear regression F-test, F(3,351) = 12.95, P = < 0.0001, ***]. (F) The preferred temperature (the average temperature at which most time was spent) was significantly lower in KO mice compared with WT mice during 0–30 min of a thermal gradient test [WT: n = 12 mice, KO: n = 9 mice, two-tailed Student’s unpaired t-test, t(19) = 2.689, P = 0.0145, *]. All data represented as mean ± SEM. *P < 0.05, ***P < 0.001.