Functional activation of Gαq coupled to 5-HT2A receptor and M1 muscarinic acetylcholine receptor in postmortem human cortical membranes

Functional activation of Gαq coupled to 5-HT2A receptor and M1 muscarinic acetylcholine receptor... Heterotrimeric guanine nucleotide-binding proteins (G-proteins) play a pivotal role in a wide range of signal transduction pathways, and receptor/G-protein coupling has been implicated in the pathophysiology of mental disorders. In this study, guanosine-5′-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding/immunoprecipitation assay for Gαq was applied to postmortem human brains. After its optimization for human prefrontal cortical membranes, we selected 5-hydroxytryptamine (5-HT) and carbachol as efficient agonists for subsequent experiments. The concentration–response curve of 5-HT shifted towards the right by the addition of increasing concentrations of ketanserin (with a pA 2 value of 9.18), indicating the involvement of the 5-HT2A receptor. Besides, the carbachol-stimulated [35S]GTPγS binding to Gαq was competitively antagonized by telenzepine (with a pA 2 value of 8.81), indicating the involvement of the M1 muscarinic acetylcholine receptor (mAChR). Concentration–response curves of 5-HT2A receptor- and M1 mAChR-mediated Gαq activation were determined in 40 subjects. The mean maximum percentage increase (%E max) was 155 and 470%, respectively, and the mean half-maximal effect concentration (EC50) was 131 nM and 15.2 µM, respectively. When the pharmacological parameters were correlated with age, postmortem delay, freezing storage period, and tissue pH, no statistically significant correlation was observed except for the negative correlation between age and %E max value of carbachol-stimulated [35S]GTPγS binding to Gαq. The %E max values for 5-HT2A receptor- and M1 mAChR-mediated Gαq activation also tended to correlate with each other. These results provide fundamental information of Gαq-coupled 5-HT2A receptor and M1 mAChR in native human brains, and lay the foundation for future studies in mental disorder patients. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Neural Transmission Springer Journals

Functional activation of Gαq coupled to 5-HT2A receptor and M1 muscarinic acetylcholine receptor in postmortem human cortical membranes

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Publisher
Springer Vienna
Copyright
Copyright © 2017 by Springer-Verlag GmbH Austria
Subject
Medicine & Public Health; Neurology; Psychiatry; Pharmacology/Toxicology; Neurosciences
ISSN
0300-9564
eISSN
1435-1463
D.O.I.
10.1007/s00702-017-1749-0
Publisher site
See Article on Publisher Site

Abstract

Heterotrimeric guanine nucleotide-binding proteins (G-proteins) play a pivotal role in a wide range of signal transduction pathways, and receptor/G-protein coupling has been implicated in the pathophysiology of mental disorders. In this study, guanosine-5′-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding/immunoprecipitation assay for Gαq was applied to postmortem human brains. After its optimization for human prefrontal cortical membranes, we selected 5-hydroxytryptamine (5-HT) and carbachol as efficient agonists for subsequent experiments. The concentration–response curve of 5-HT shifted towards the right by the addition of increasing concentrations of ketanserin (with a pA 2 value of 9.18), indicating the involvement of the 5-HT2A receptor. Besides, the carbachol-stimulated [35S]GTPγS binding to Gαq was competitively antagonized by telenzepine (with a pA 2 value of 8.81), indicating the involvement of the M1 muscarinic acetylcholine receptor (mAChR). Concentration–response curves of 5-HT2A receptor- and M1 mAChR-mediated Gαq activation were determined in 40 subjects. The mean maximum percentage increase (%E max) was 155 and 470%, respectively, and the mean half-maximal effect concentration (EC50) was 131 nM and 15.2 µM, respectively. When the pharmacological parameters were correlated with age, postmortem delay, freezing storage period, and tissue pH, no statistically significant correlation was observed except for the negative correlation between age and %E max value of carbachol-stimulated [35S]GTPγS binding to Gαq. The %E max values for 5-HT2A receptor- and M1 mAChR-mediated Gαq activation also tended to correlate with each other. These results provide fundamental information of Gαq-coupled 5-HT2A receptor and M1 mAChR in native human brains, and lay the foundation for future studies in mental disorder patients.

Journal

Journal of Neural TransmissionSpringer Journals

Published: Jul 7, 2017

References

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