Higher power images of co-expression of GAD67 and nAChR subunit mRNAs in hippocampal interneurons detected with double in situ hybridization. Expression of GAD67 and nAChR subunit mRNA for A) α2, B) α3, C) α4, D) α5, E) α6, F) α7, G) β2, H) β3, and I) β4 detected by dual exposure to light- and darkfield. J) Double in situ hybridization with the Dig-GAD67 probe and a 35S-nAChR sense probe for α7 used as a negative control. Asterisks indicate neurons with co-expression of mRNA s for GAD67 and a nAChR subunit; white arrows point to single-labeled neurons expressing nAChR subunit mRNA only; black arrows point to single-labeled GAD67 expressing neurons. Abbreviations: CA1 s.ori, CA1 stratum oriens; CA3 s.pyr, CA3 stratum pyramidale; CA1 s.rad/LM, CA1 stratum radiatum/lacunosum moleculare; DG mol, dentate gyrus molecular layer. Scale bar = 50 μm.