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Ding C, Bremer NM, Smith TD, Seitz PK, Anastasio NC, Cunningham KA, Zhou J. Exploration of synthetic approaches and pharmacological evaluation of PNU-69176E and its stereoisomer as 5-HT2C receptor allosteric modulators. ACS Chem Neurosci 2012; 3:538-45. [PMID: 22860223 DOI: 10.1021/cn300020x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 04/19/2012] [Indexed: 11/30/2022] Open
Abstract
Allosteric modulators of the serotonin (5-HT) 5-HT(2C) receptor (5-HT(2C)R) present a unique drug design strategy to augment the response to endogenous 5-HT in a site- and event-specific manner with great potential as novel central nervous system probes and therapeutics. To date, PNU-69176E is the only reported selective positive allosteric modulator for the 5-HT(2C)R. For the first time, an optimized synthetic route to readily access PNU-69176E (1) and its diastereomer 2 has been established in moderate to good overall yields over 10 steps starting from commercially available picolinic acid. This synthetic approach not only enables a feasible preparation of a sufficient amount of 1 for use as a reference compound for secondary pharmacological studies, but also provides an efficient synthesis of key intermediates to develop novel and simplified 5-HT(2C)R allosteric modulators. Compound 1 and its diastereomer 2 were functionally characterized in Chinese hamster ovary (CHO) cells stably transfected with the 5-HT(2C)R using an intracellular calcium (Ca(i) (2+)) release assay. Compound 1 demonstrated efficacy and potency as an allosteric modulator for the 5-HT(2C)R with no intrinsic agonist activity. Compound 1 did not alter 5-HT-evoked Ca(i) (2+) in CHO cells stably transfected with the highly homologous 5-HT(2A)R. In contrast, the diastereomer 2 did not alter 5-HT-evoked Ca(i) (2+) release in 5-HT(2A)R-CHO or 5-HT(2C)R-CHO cells or exhibit intrinsic agonist activity.
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Affiliation(s)
- Chunyong Ding
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
| | - Nicole M. Bremer
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
| | - Thressa D. Smith
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
| | - Patricia K. Seitz
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
| | - Noelle C. Anastasio
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
| | - Kathryn A. Cunningham
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
| | - Jia Zhou
- Chemical
Biology Program, Department of Pharmacology and Toxicology, ‡Center for Addiction
Research, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, United States
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Seitz PK, Bremer NM, McGinnis AG, Cunningham KA, Watson CS. Quantitative changes in intracellular calcium and extracellular-regulated kinase activation measured in parallel in CHO cells stably expressing serotonin (5-HT) 5-HT2A or 5-HT2C receptors. BMC Neurosci 2012; 13:25. [PMID: 22397586 PMCID: PMC3380724 DOI: 10.1186/1471-2202-13-25] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 03/07/2012] [Indexed: 01/14/2023] Open
Abstract
Background The serotonin (5-HT) 2A and 2C receptors (5-HT2AR and 5-HT2CR) are involved in a wide range of physiological and behavioral processes in the mammalian central and peripheral nervous systems. These receptors share a high degree of homology, have overlapping pharmacological profiles, and utilize many of the same and richly diverse second messenger signaling systems. We have developed quantitative assays for cells stably expressing these two receptors involving minimal cell sample manipulations that dramatically improve parallel assessments of two signaling responses: intracellular calcium (Cai++) changes and activation (phosphorylation) of downstream kinases. Such profiles are needed to begin to understand the simultaneous contributions from the multiplicity of signaling cascades likely to be initiated by serotonergic ligands. Results We optimized the Cai++ assay for stable cell lines expressing either 5-HT2AR or 5-HT2CR (including dye use and measurement parameters; cell density and serum requirements). We adapted a quantitative 96-well plate immunoassay for pERK in the same cell lines. Similar cell density optima and time courses were observed for 5-HT2AR- and 5-HT2CR-expressing cells in generating both types of signaling. Both cell lines also require serum-free preincubation for maximal agonist responses in the pERK assay. However, 5-HT2AR-expressing cells showed significant release of Cai++ in response to 5-HT stimulation even when preincubated in serum-replete medium, while the response was completely eliminated by serum in 5-HT2CR-expressing cells. Response to another serotonergic ligand (DOI) was eliminated by serum-replete preincubation in both cells lines. Conclusions These data expand our knowledge of differences in ligand-stimulated signaling cascades between 5-HT2AR and 5-HT2CR. Our parallel assays can be applied to other cell and receptor systems for monitoring and dissecting concurrent signaling responses.
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Affiliation(s)
- Patricia K Seitz
- Center for Addiction Research, University of Texas Medical Branch, Galveston, TX 77555, USA
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