Fig. 4

Propranolol microinjections in the LC prevents TCC sensitization and cutaneous allodynia. Left panels: techniques and treatments depicted in each line. A Time courses of static mechanical withdrawal thresholds and (B) dynamic mechanical scores (DMS) of the face after a 1st (unfilled symbols) or 4th IS (colored symbols) injection in vehicle (squares)- or propranolol-treated rats (triangles). Cutaneous mechanical sensitivity was assessed before and at 30 min intervals for 3 h after IS injection (black arrows at t0). Static mechanical thresholds were measured with VF hairs applied on the face and dynamic mechanical scores by gentle air puffing. (C) to (E) Electrophysiological recordings (TCC) from the same animals as in (A) and (B). C Spontaneous, (D) VF-evoked, and (E) brush-evoked activities from IS4 + aCSF (left boxplots) and IS4 + propranolol rats (right boxplots). Horizontal line in boxplots represents median, bottom and top edges 25th and 75th percentiles respectively, and dots represent individual values. For all conditions, n = 5. * P < 0.05, ** P < 0.01, *** P < 0.001; two-way ANOVA for (A) and (B) (aCSF vs propranolol microinjection, on 1st or 4th IS injection), Mann–Whitney U test for (C), Student’s t test for (D) and (E). IS1 = 1st IS injection (naive animals), IS4 = 4th IS injection (sensitized animals) and the corresponding experimental groups