The relationship of thyrotropin‐releasing hormone (TRH)‐expressing dorsal horn neurons to cholecystokinin (CCK), protein kinase Cγ (PKCγ), and neurotensin. (a–c) A scan through laminae II and III from a section reacted with probes against TRH, CCK, and PKCγ mRNAs, and counterstained with NucBlue. Three TRH+ cells are marked with arrows, and all of these are positive for both CCK and PKCγ mRNAs. Asterisks indicate two PKCγ cells that lack message for TRH and CCK, while the arrowheads show two CCK cells that are negative for TRH and PKCγ. (d–f) A scan through the equivalent region from a section reacted with probes against TRH, neurotensin, and PKCγ mRNAs, and counterstained with NucBlue. Two TRH+ cells that contain mRNA for PKCγ, but not for neurotensin, are indicated with arrows. The arrowheads point to two cells that are positive for neurotensin and PKCγ mRNA, but negative for TRH mRNA. All images were obtained from single optical sections. Scale bar = 20 μm [Color figure can be viewed at wileyonlinelibrary.com]