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Won W, Kim D, Shin E, Lee CJ. Mapping Astrocytic and Neuronal μ-opioid Receptor Expression in Various Brain Regions Using MOR-mCherry Reporter Mouse. Exp Neurobiol 2023; 32:395-409. [PMID: 38196135 PMCID: PMC10789176 DOI: 10.5607/en23039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 12/23/2023] [Accepted: 12/27/2023] [Indexed: 01/11/2024] Open
Abstract
The μ-opioid receptor (MOR) is a class of opioid receptors characterized by a high affinity for β-endorphin and morphine. MOR is a G protein-coupled receptor (GPCR) that plays a role in reward and analgesic effects. While expression of MOR has been well established in neurons and microglia, astrocytic MOR expression has been less clear. Recently, we have reported that MOR is expressed in hippocampal astrocytes, and its activation has a critical role in the establishment of conditioned place preference. Despite this critical role, the expression and function of astrocytic MOR from other brain regions are still unknown. Here, we report that MOR is significantly expressed in astrocytes and GABAergic neurons from various brain regions including the hippocampus, nucleus accumbens, periaqueductal gray, amygdala, and arcuate nucleus. Using the MOR-mCherry reporter mice and Imaris analysis, we demonstrate that astrocytic MOR expression exceeded 60% in all tested regions. Also, we observed similar MOR expression of GABAergic neurons as shown in the previous distribution studies and it is noteworthy that MOR expression is particularly in parvalbumin (PV)-positive neurons. Furthermore, consistent with the normal MOR function observed in the MOR-mCherry mouse, our study also demonstrates intact MOR functionality in astrocytes through iGluSnFr-mediated glutamate imaging. Finally, we show the sex-difference in the expression pattern of MOR in PV-positive neurons, but not in the GABAergic neurons and astrocytes. Taken together, our findings highlight a substantial astrocytic MOR presence across various brain regions.
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Affiliation(s)
- Woojin Won
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Daeun Kim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
- Department of Biomedical Engineering, College of Information and Biotechnology, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Eunjin Shin
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - C. Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
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Jern P, Chen J, Tuisku J, Saanijoki T, Hirvonen J, Lukkarinen L, Manninen S, Helin S, Putkinen V, Nummenmaa L. Endogenous Opioid Release After Orgasm in Man: A Combined PET/Functional MRI Study. J Nucl Med 2023:jnumed.123.265512. [PMID: 37442599 PMCID: PMC10394307 DOI: 10.2967/jnumed.123.265512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 05/10/2023] [Indexed: 07/15/2023] Open
Abstract
The endogenous μ-opioid receptor (MOR) system plays a key role in the mammalian reward circuit. Human and animal experiments suggest the involvement of MORs in human sexual pleasure, yet this hypothesis currently lacks in vivo support. Methods: We used PET with the radioligand [11C]carfentanil, which has high affinity for MORs, to quantify endogenous opioid release after orgasm in man. Participants were scanned once immediately after orgasm and once in a baseline state. Hemodynamic activity was measured with functional MRI during penile stimulation. Results: The PET data revealed significant opioid release in the hippocampus. Hemodynamic activity in the somatosensory and motor cortices and in the hippocampus and thalamus increased during penile stimulation, and thalamic activation was linearly dependent on self-reported sexual arousal. Conclusion: Our data show that endogenous opioidergic activation in the medial temporal lobe is centrally involved in sexual arousal, and this circuit may be implicated in orgasmic disorders.
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Affiliation(s)
- Patrick Jern
- Department of Psychology, Åbo Akademi University, Turku, Finland;
| | - Jinglu Chen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
| | - Jouni Tuisku
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
| | - Tiina Saanijoki
- Turku PET Centre, University of Turku, Turku, Finland
- Turku BioImaging, University of Turku and Åbo Akademi University, Turku, Finland
| | - Jussi Hirvonen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
- Department of Radiology, University of Turku, Turku, Finland
| | - Lasse Lukkarinen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
| | - Sandra Manninen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
| | - Semi Helin
- Turku PET Centre, University of Turku, Turku, Finland
| | - Vesa Putkinen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
- Turku Institute for Advanced Study, University of Turku, Turku, Finland
| | - Lauri Nummenmaa
- Turku PET Centre, University of Turku, Turku, Finland
- Turku University Hospital, University of Turku, Turku, Finland
- Department of Psychology, University of Turku, Turku, Finland; and
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