Fig. 1

IS-induced up-regulation of c-fos can be abolished through block of TRPV1. a Intracisternal administration of inflammatory soup (IS; black bars) induces an increase in the amount of cells showing c-fos like immunoreactivity (c-fos LI) in the trigeminal brain stem complex. This increase was significant at all levels of the TNC when compared to control animals (white bars), injected with an identical volume of vehicle. These two groups also received an injection of sumatriptan vehicle. Administration of sumatriptan (300 μg/kg; grey bars) before injection of IS did not affect the IS-induced up-regulation of c-fos. b The TRPV1 antagonist JNJ-38893777 reduced the elevated c-fos expression, seen after injection of IS, in a dose-dependent fashion. The antagonist was injected intravenously in 0.03 mg/kg (black bars), 0.3 mg/kg (light grey bars) and 3 mg/kg (dark grey bars) over a period of 20 min before application of IS. c The TRPV1 antagonist JNJ-17203212 was injected in 0.3 mg/kg (black bars), 3 mg/kg (light grey bars) and 30 mg/kg (dark grey bars) previous to IS administration. A dose-dependent reduction in IS-induced c-fos expression could be observed. The highest dose completely abolished c-fos up-regulation in most parts of the TNC. # compares to vehicle + vehicle treated group (no IS administration) at the same level of TNC. * compares to IS + vehicle treated group at the same level of TNC. n.s. not significant (compared to IS + vehicle). *p < 0.05; **p < 0.01; ***p < 0.001