Immunohistograms (A) and the average of total length of CGRP-ir nerve fiber length (B) in the dura mater of rats in i.c. capsaicin-treated group with various pretreatments as in Figure 1, as well as in Sham group (a, b). Note that Compound 6 at 3 or 10, but not 1, mg/kg significantly suppressed capsaicin-induced depletion of dura CGRP-ir in a manner comparable to topiramate. The capsaicin-induced CGRP depletion inhibited by Compound 6 at 3 mg/kg is significantly reversed by furosemide. Loreclezole and Ro 15–4513 significantly inhibit capsaicin induced CGRP depletion in the dura, but diazepam does not. Scale bar: 1000 μm (a), 400 (b) and 100 μm (c). The length of CGRP-ir nerve fiber (arrowhead), stained by immunohistochemistry, in the dura mater was quantified by Image J. The total length of CGRP-ir fiber length (in pixel) in six fixed comparable areas of the dura mater in each rat was collected. Arrow head: CGRP-ir nerve fiber; Open arrow head: dural vessel. Data presentation and statistical analyses are the same as in Fig. 1.