Distribution of prostaglandin EP(3) and EP(4) receptor mRNA in the rat parabrachial nucleus.

By using in situ hybridization, the distribution of mRNA for the PGE(2) receptors EP(3) and EP(4) was examined in the rat parabrachial nucleus (PB), a major brain stem relay for autonomic and nociceptive processing. EP(3) receptor mRNA was present in most subnuclei, with the densest labeling in the external lateral, dorsal lateral, superior lateral, central lateral and Kölliker-Fuse nuclei. EP(4) receptor mRNA expressing cells had a more restricted distribution, largely being confined to the superior lateral and adjacent parts of the dorsal and central lateral nuclei in a pattern complementary to that for EP(3) receptor mRNA. These findings suggest that EP(3) and EP(4) receptors in PB have distinct functional roles that include nociceptive processing, blood pressure regulation and feeding behavior.