Sphingosine-1-phosphate (S1P) is an important lipid mediator interacting with a group of five G-protein coupled receptors (S1P1-5). S1P receptors are expressed in a variety of tissues where they are known to regulate various physiological processes. Behavioural tests showed that C57BL6J mice with TRPV1 receptors (nociceptor specific heat transducer) develop heat hyperalgesia after injection of S1P [100mM] into the paw (Hargraves test). These results were confirmed in vitro where S1P [1 mM] induced an increase of the heat response magnitudes in heat-sensitive C-fibres from 2.03 0.39 impulses/s to 3.21 0.50 impulses/s. In single sensory neurons isolated from mouse dorsal root ganglion, S1P facilitated heat-activated currents and induced a significant shift of the activation threshold of the current towards lower temperatures. Additionally, capsaicin-activated currents increased dose-dependently after S1P application with the increase disappearing after pretreatment with pertussis toxin, an inhibitor of G-proteins. The presence of S1P1, S1P2 and S1P3 receptors in sensory neurons was demonstrated on the transcriptional and translational level. All S1P receptors couple to G_i proteins which may activate PI3K via ßg-subunits. Blocking PI3K by wortmannin [1mM] significantly reduced sensitisation of capsaicin-activated currents. Inhibition of the downstream enzymes p38-MAP kinase or PKC via SB203580 [1mM] or BIM1 [1mM] similarly inhibited sensitisation. Together, our data suggest that S1P induces heat hyperalgesia in mice by a receptor-dependent modulation via phosphorylation of TRPV1.