OSM requires the expression of gp130 in nociceptive neurons to potentiate capsaicin-evoked currents. (A) Expression of OSMR, gp130 and TRPV1 in gp130fl/fl and SNS-gp130-/- cultured DRG neurons. OSMR and gp130 immunoreactivity was observed in gp130fl/fl DRG neurons (upper panel). In addition, the OSMR-positive neurons of gp130fl/fl mice also displayed TRPV1 immunoreactivity (middle panel). The SNS-gp130-/- DRG neurons were devoid of gp130 (lower panel) while maintaining OSMR expression. Scale bar 10 μM. (B) In electrophysiological recordings of gp130fl/fl neurons OSM (5 ng/ml) induces a transient potentiation of capsaicin-responsive currents (upper trace), whereas in DRG neurons lacking the gp130 expression OSM did not increase the capsaicin-induced currents (lower trace). Quantification of normalized ionic currents (Icaps/IcapsIII) reveals that OSM increases capsaicin currents approximately 2.5 fold within 2 minutes in OSMR-positive gp130 nociceptors compared to the normalized currents recorded in OSMR-positive/gp130-negative SNS-gp130-/- nociceptive neurons. ** p < 0.01, *** p < 0.001, Mann-Whitney U-test, white numbers inside the individual bars indicate the number of recorded Icaps.