Co-expression of α7 and β2 nicotinic acetylcholine receptor subunit mRNAs within rat brain cholinergic neurons
Section snippets
Materials
The following materials were obtained from the indicated sources: bovine serum albumin, polyvinyl pyrrolidone, poly-l-lysine, RNase A (Sigma, St. Louis, MO, USA); pBluescript II SK+ (Stratagene, La Jolla, CA, USA); anti-digoxygenin (Dig)-AP Fab antibody, Dig-rUTP, Genius system nonradioactive nucleic acid detection kit, restriction enzymes, T3, T7 polymerases, proteinase K and yeast tRNA (Boehringer Mannheim Biochemicals, Indianapolis, IN, USA); formamide (Fluka, Ronkonkoma, NY, USA); dextran
Dig probe sensitivity
One caveat of using Dig-labeled riboprobes is their lower tissue penetration compared to the 35S-labeled riboprobes, due to the large size of the Dig molecule. Impaired tissue penetration leads to a lower sensitivity of the non-radioactive in situ hybridization. In order to examine this issue, we performed double-labeling in situ hybridization combining radioactive and non-radioactive riboprobes for both ChAT and GAD. The areas chosen for the analysis were the septohippocampal projection
Discussion
The goal of the present study was to identify which nAChR subunit mRNAs are expressed within cholinergic projection neurons of the basal forebrain and mesopontine tegmentum, and in forebrain cholinergic interneurons, in order to gain insight as to which possible subtype(s) of nAChR may regulate central ACh release. Although the results presented here deal exclusively with mRNA expression, they provide information as to the nAChR subunits that can potentially form functional receptors. The nAChR
Conclusions
In summary, the results of the present study indicate that cholinergic projection neurons and forebrain cholinergic interneurons express a similar pattern of nAChR subunit mRNAs, suggesting a mechanism by which both ACh and nicotine can directly stimulate these neurons. The nAChRs on basal forebrain cholinergic and GABAergic neurons may serve as additional targets that mediate the cognitive-enhancing properties of nicotine and other nicotinic ligands. A number of subtype-selective nicotinic
Acknowledgements
This work was supported by NIH grants DA10612, DA13332 and dissertation fellowship 8DT-0168 (L.A.) from California Tobacco Related Disease Research Program.
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