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Nunes EJ, Rupprecht LE, Foster DJ, Lindsley CW, Conn PJ, Addy NA. Examining the role of muscarinic M5 receptors in VTA cholinergic modulation of depressive-like and anxiety-related behaviors in rats. Neuropharmacology 2020; 171:108089. [PMID: 32268153 PMCID: PMC7313677 DOI: 10.1016/j.neuropharm.2020.108089] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/21/2020] [Accepted: 04/02/2020] [Indexed: 12/14/2022]
Abstract
Acetylcholine is implicated in mood disorders including depression and anxiety. Increased cholinergic tone in humans and rodents produces pro-depressive and anxiogenic-like effects. Cholinergic receptors in the ventral tegmental area (VTA) are known to mediate these responses in male rats, as measured by the sucrose preference test (SPT), elevated plus maze (EPM), and the forced swim test (FST). However, these effects have not been examined in females, and the VTA muscarinic receptor subtype(s) mediating the pro-depressive and anxiogenic-like behavioral effects of increased cholinergic tone are unknown. We first examined the behavioral effects of increased VTA cholinergic tone in male and female rats, and then determined whether VTA muscarinic M5 receptors were mediating these effects. VTA infusion of the acetylcholinesterase inhibitor physostigmine (0.5 μg, 1 μg and 2 μg/side) in males and females produced anhedonic-like, anxiogenic, pro-depressive-like responses on the SPT, EPM, and FST. In females, VTA administration of the muscarinic M5 selective negative allosteric modulator VU6000181 (0.68 ng, 2.3 ng, 6.8 ng/side for a 3 μM, 10 μM, 30 μM/side infusion) did not alter SPT, EPM nor FST behavior. However, in males intra-VTA infusion of VU6000181 alone reduced time spent immobile on the FST. Furthermore, co-infusion of VU6000181 with physostigmine, in male and female rats, attenuated the pro-depressive and anxiogenic-like behavioral responses induced by VTA physostigmine alone, in the SPT, EPM, and FST. Together, these data reveal a critical role of VTA M5 receptors in mediating the anhedonic, anxiogenic, and depressive-like behavioral effects of increased cholinergic tone in the VTA.
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Affiliation(s)
- Eric J Nunes
- Department of Psychiatry, Yale School of Medicine, New Haven, 06511, CT, USA
| | - Laura E Rupprecht
- Department of Psychiatry, Yale School of Medicine, New Haven, 06511, CT, USA
| | - Daniel J Foster
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, USA; Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, USA; Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, USA; Vanderbilt Kennedy Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Nii A Addy
- Department of Psychiatry, Yale School of Medicine, New Haven, 06511, CT, USA; Department of Cellular and Molecular Physiology, Yale University, New Haven, 06511, CT, USA; Interdepartmental Neuroscience Program, Yale University, New Haven, 06511, CT, USA.
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McGowan KM, Nance KD, Cho HP, Bridges TM, Conn PJ, Jones CK, Lindsley CW. Continued optimization of the M 5 NAM ML375: Discovery of VU6008667, an M 5 NAM with high CNS penetration and a desired short half-life in rat for addiction studies. Bioorg Med Chem Lett 2017; 27:1356-1359. [PMID: 28237763 DOI: 10.1016/j.bmcl.2017.02.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 02/06/2017] [Accepted: 02/07/2017] [Indexed: 11/19/2022]
Abstract
This letter describes the continued optimization of M5 NAM ML375 (VU0483253). While a valuable in vivo tool compound, ML375has an excessively long elimination half-life in rat (t1/2=80h), which can be problematic in certain rodent addiction paradigms (e.g., reinstatement). Thus, we required an M5 NAM of comparable potency to ML375, but with a rat t1/2 of less than 4h. Steep SAR plagued this chemotype, and here we detail aniline replacements that offered some improvements over ML375, but failed to advance. Ultimately, incorporation of a single methyl group to the 9b-phenyl ring acted as a metabolic shunt, providing (S)-11 (VU6008667), an equipotent M5 NAM, with high CNS penetration, excellent selectivity versus M1-4 and the desired short half-life (t1/2=2.3h) in rat.
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Affiliation(s)
- Kevin M McGowan
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Kellie D Nance
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Hykeyung P Cho
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Thomas M Bridges
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Carrie K Jones
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology and Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN 37232, USA.
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