Classification of Neuronal Nicotinic Acetylcholine Receptors in Rat CA1 Hippocampal Interneuron Subpopulations Defined by Calcium-Binding Protein mRNA Expression

• Main Author: Burgon, Richard M.
• Format: Others
• Published: BYU ScholarsArchive 2006
• Subjects: nicotinic; acetylcholine; ion channel; hippocampus; interneuron; Neuroscience and Neurobiology
• Online Access: https://scholarsarchive.byu.edu/etd/943; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=1942&context=etd

In this study, the single-cell relative quantitative mRNA expression of three Calcium-binding proteins (CaBPs; calbindin, calretinin, parvalbumin) and eight nicotinic acetylcholine receptor (nAChR) subunits (alpha2-alpha5, alpha7, beta2-beta4) from interneurons from the stratum radiatum or stratum oriens within the CA1 region of rat hippocampi was analyzed using quantitative real time RT-PCR. Eighty-seven percent of the interneurons examined expressed CaBP mRNA. Parvalbumin mRNA was detected in 64%, while calbindin and calretinin expression was detected in 26% and 40% of interneurons, respectively. CaBP expression was not exclusive; the average number of CaBP mRNA detected per interneuron of the 47 interneurons examined for CaBP was 1.3. There was no significant difference between the proportion of CaBPs expressed in the stratum radiatum compared to the stratum oriens. However, interneurons from the stratum radiatum expressed significantly higher relative levels of mRNA for calbindin. Eighty-four percent of the 31 interneurons examined for both CaBP and nAChR subunits expressed nAChR subunit mRNA; the average number of nAChR subunits detected per interneuron was 2.9. Furthermore, of the 24, 140, and 168 possible combinations of 2-, 3-, and 4-way co-expression between CaBP+nAChR mRNA, respectively, only two significant 3-way combinations were detected: parvalbumin+a3+a5 and parvalbumin+alpha5+beta4. This study reports that subpopulations of nAChR-containing interneurons defined by quantitative CaBP mRNA expression or CaBP+nAChR co-expression do exist within the CA1 region of the hippocampus.