Figure 2

Neurochemical signal transduction pathways in the PSDC neurons in response to visceral stimuli. The activation of nociceptive receptors causes a large influx of calcium into the nociceptive neurons and the increased calcium influx, in turn, activates multiple intracellular protein kinases. PKA regulates the phosphorylation of glutamate receptors. Another important role for the activation of PKA in PSDC neurons is its effect on painful stimulation-elicited gene expression through mediation of transcription factors, such as c-fos and CREB. PKA in PSDC neurons might increase the expression of NK1 receptors through mediation of CREB and contribute to the sensitization of PSDC neurons.