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. 2013 Nov 18;8(11):e81018. doi: 10.1371/journal.pone.0081018

Figure 6. The effects of acupuncture at HT7 require large A-fiber activation of ulnar nerve.

Figure 6

A: HT7 effects are not blocked by a perineural injection of RTX (resiniferatoxin; a C/Aδ-fiber inhibitor) into ulnar nerve (RTX+HT7). B: Direct injection of capsaicin into HT7 to stimulate C/Aδ-fibers failed to produce HT7 effects (Capsaicin in HT7). *P<0.05 compared to control (cocaine only). n= 6-8 rats for each group of A-B. Data are presented as mean ± SEM and analyzed by one or two-way repeated ANOVA with Holm-Sidak post hoc comparison.

C, D: Epifluorescent images showing IB4-labelled neurons in C8 DRG of a rat injected with IB4 into RTX- and vehicle-treated ulnar nerve. An FITC IB4 tracer (FITC-conjugated isolectin B4) was administered into ulnar nerve on the both side of rats, 48 hours after perineural injection of either RTX or vehicle into right and left ulnar nerve, respectively. Numerous IB4-labelled cells of small size are shown in vehicle-treated DRG (C), whereas a few IB4-labelled neurons are found in the RTX-treated DRG (D). It indicates that retrograde labeling of C-fibers by FITC IB4 tracer is blocked by perineural injection of RTX, but not vehicle. Bar=100 μm.