Fig. 4.

siRNA targeted to S1PR₁ blocks the sensitization to SEW2871, although S1P can still sensitize some neurons. After neurons were treated with 200 nM siRNA targeted to S1PR₁ (fluorescently labeled) using our standard protocol, they were used for recordings. The 11 small diameter sensory neurons that were exposed to 100 nM SEW2871 failed to exhibit an increase in AP firing by the ramp over a 10-min period. Of the 11 neurons, 9 were exposed to 1 μM S1P for another 10 min. Six of the 9 neurons remained unaffected after exposure to S1P, whereas 3 of the 9 exhibited increased firing after S1P. The asterisks indicate a significant difference compared with the 10-min SEW2871 condition with P < 0.05, ANOVA.