Localization of molecules involved in cytokine receptor signaling in the rat trigeminal ganglion

The localization of some cytokine receptors and their downstream intracellular signaling molecules was examined in the trigeminal ganglia of rats. Among cytokine receptor components, we examined signal transduction subchain, gp130, IL-2R gamma and IL-5R beta, which are common to respective groups of cytokine receptors. Most of the sensory ganglion neurons expressed gp130, but not IL-2R gamma nor IL-5R beta. We further examined the localization of Janus kinase (JAK) family members which were reported to be associated with various kind of cytokine receptors and are thought to be implicated in major cytokine receptor-signaling pathways [6,9,11,13]. While JAK1 and Tyk2 were expressed in all the type of neurons, JAK2 was predominantly expressed in the small neurons. In addition, JAK3 immunoreactivity was only found in satellite cells. The present results indicate that most of neurons express gp130, and that the localization of JAK family members differs with the cell type. This also suggests that the cytokine receptor-signaling pathway may be different in neuronal and glial cells.