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Aomine Y, Oyama Y, Sakurai K, Macpherson T, Ozawa T, Hikida T. Clozapine N-oxide, compound 21, and JHU37160 do not influence effortful reward-seeking behavior in mice. Psychopharmacology (Berl) 2024; 241:89-96. [PMID: 37792024 PMCID: PMC10774210 DOI: 10.1007/s00213-023-06465-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 09/04/2023] [Indexed: 10/05/2023]
Abstract
RATIONALE Clozapine N-oxide (CNO) has been developed as a ligand to selectively activate designer receptors exclusively activated by designer drugs (DREADDs). However, previous studies have revealed that peripherally injected CNO is reverse-metabolized into clozapine, which, in addition to activating DREADDs, acts as an antagonist at various neurotransmitter receptors, suggesting potential off-target effects of CNO on animal physiology and behaviors. Recently, second-generation DREADD agonists compound 21 (C21) and JHU37160 (J60) have been developed, but their off-target effects are not fully understood. OBJECTIVES The present studies assessed the effect of novel DREADD ligands on reward-seeking behavior. METHODS We first tested the possible effect of acute i.p. injection of low-to-moderate (0.1, 0.3, 1, 3 mg/kg) of CNO, C21, and J60 on motivated reward-seeking behavior in wild-type mice. We then examined whether a high dose (10 mg/kg) of these drugs might be able to alter responding. RESULTS Low-to-moderate doses of all drugs and a high dose of CNO or C21 did not alter operant lick responding for a reward under a progressive ratio schedule of reinforcement, in which the number of operant lick responses to obtain a reward increases after each reward collection. However, high-dose J60 resulted in a total lack of responding that was later observed in an open field arena to be due to a sedative effect. CONCLUSIONS This study provides definitive evidence that commonly used doses of CNO, C21, and J60 have negligible off-target effects on motivated reward-seeking but urges caution when using high doses of J60 due to sedative effects.
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Affiliation(s)
- Yoshiatsu Aomine
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Yoshinobu Oyama
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Koki Sakurai
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
- Laboratory of Protein Profiling and Functional Proteomics, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | - Tom Macpherson
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Takaaki Ozawa
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
| | - Takatoshi Hikida
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
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Aomine Y, Sakurai K, Macpherson T, Ozawa T, Miyamoto Y, Yoneda Y, Oka M, Hikida T. Importin α3 (KPNA3) Deficiency Augments Effortful Reward-Seeking Behavior in Mice. Front Neurosci 2022; 16:905991. [PMID: 35844217 PMCID: PMC9279672 DOI: 10.3389/fnins.2022.905991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Importin α3 (Gene: Kpna3, the ortholog of human Importin α4) is a member of the importin α family and participates in nucleocytoplasmic transport by forming trimeric complexes between cargo proteins and importin β1. Evidence from human studies has indicated that single nucleotide polymorphisms (SNP) in the KPNA3 gene are associated with the occurrence of several psychiatric disorders accompanied by abnormal reward-related behavior, including schizophrenia, major depression, and substance addiction. However, the precise roles of importin α3 in controlling reward processing and motivation are still unclear. In this study, we evaluated the behavioral effects of Kpna3 knockout (KO) in mice on performance in touchscreen operant chamber-based tasks evaluating simple (fixed-ratio) and effortful (progressive-ratio) reward-seeking behaviors. While Kpna3 KO mice showed no significant differences in operant reward learning on a fixed-ratio schedule, they demonstrated significantly increased motivation (increased break point) to instrumentally respond for sucrose on a progressive-ratio schedule. We additionally measured the number of c-Fos-positive cells, a marker of neural activity, in 20 regions of the brain and identified a network of brain regions based on their interregional correlation coefficients. Network and graph-theoretic analyses suggested that Kpna3 deficiency enhanced overall interregional functional connectivity. These findings suggest the importance of Kpna3 in motivational control and indicate that Kpna3 KO mice may be an attractive line for modeling motivational abnormalities associated with several psychiatric disorders.
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Affiliation(s)
- Yoshiatsu Aomine
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Koki Sakurai
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Tom Macpherson
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Takaaki Ozawa
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Yoichi Miyamoto
- Laboratory of Nuclear Transport Dynamics, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - Yoshihiro Yoneda
- National Institutes for Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - Masahiro Oka
- Laboratory of Nuclear Transport Dynamics, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - Takatoshi Hikida
- Laboratory for Advanced Brain Functions, Institute for Protein Research, Osaka University, Osaka, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
- *Correspondence: Takatoshi Hikida,
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