Coexpression of the cannabinoid receptor type 1 with dopamine and serotonin receptors in distinct neuronal subpopulations of the adult mouse forebrain
Section snippets
Animals and tissue preparation
Animals were housed in a temperature- and humidity-controlled room with a 12 h light-dark cycle (light from 07:00–19:00) and with access to food and water ad libitum. The experimental protocols were approved by the Ethical Committee on Animal Care and Use of the Government of Bavaria, Germany.
Adult mice (3–5 months old; C57BL/6) were killed by cervical dislocation. Brains were removed, snap-frozen on dry-ice and stored at -80°C prior to sectioning. Brains were mounted on Tissue Tek
CB1 and D1 receptors
The highest levels of D1 transcripts are observed in the basal ganglia (Mansour et al., 1991, Weiner et al., 1991), including caudate putamen, nucleus accumbens, and olfactory tubercle. High levels of low-CB1-expressing cells are detected in the dorsolateral caudate putamen, while the nucleus accumbens contains only few low-CB1-expressing cells. The olfactory tubercle shows an intense staining due to a high density of low-CB1-expressing cells. Coexpressing cells were counted at a single-cell
Discussion
Increasing evidence indicates that a single receptor subtype may be linked to the formation of multiple, intracellular signals. However, it is unlikely that all signals driven by a single receptor subtype are equally operative under all circumstances, but it seems that the functional weight of one pathway relative to another can be altered by interactions with other receptors. The first indication for possible interactions between different receptors is given, when both receptors are expressed
Acknowledgements
We would like to thank Christine Schleicher for technical assistance, Dr. Thomas Lemberger (DKFZ, Heidelberg, Germany) for the D1 probe used for in situ hybridization experiments, Drs. Walter Sierralta and Gregor Eichele (MPI of Experimental Endocrinology, Hannover, Germany) for the experimental in situ hybridization protocol and Dr. Daniela Vogt-Weisenhorn for critical reading of the manuscript and valuable comments. This work was in part supported by a Grant from Deutsche
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