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Borroto-Escuela DO, Cuesta-Marti C, Lopez-Salas A, Chruścicka-Smaga B, Crespo-Ramírez M, Tesoro-Cruz E, Palacios-Lagunas DA, Perez de la Mora M, Schellekens H, Fuxe K. The oxytocin receptor represents a key hub in the GPCR heteroreceptor network: potential relevance for brain and behavior. Front Mol Neurosci 2022; 15:1055344. [PMID: 36618821 PMCID: PMC9812438 DOI: 10.3389/fnmol.2022.1055344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/11/2022] [Indexed: 12/24/2022] Open
Abstract
In the last 10 years, it has become increasingly clear that large numbers of axon collaterals extend from the oxytocin (OXT) hypothalamic axons, especially the parvocellular components, to other brain regions. Consequently, the OXT signaling system forms, like other monoamine axons, a rich functional network across several brain regions. In this manuscript, we review the recently indicated higher order G-protein coupled heteroreceptor complexes of the oxytocin receptor (OXTR), and how these, via allosteric receptor-receptor interactions modulate the recognition, signaling, and trafficking of the participating receptor protomers and their potential impact for brain and behavior. The major focus will be on complexes of the OXTR protomer with the dopamine D2 receptor (D2R) protomer and the serotonin 2A (5-HT2AR) and 2C (5-HT2CR) receptor protomers. Specifically, the existence of D2R-OXTR heterocomplexes in the nucleus accumbens and the caudate putamen of rats has led to a postulated function for this heteromer in social behavior. Next, a physical interaction between OXTRs and the growth hormone secretagogue or ghrelin receptor (GHS-R1a) was demonstrated, which consequently was able to attenuate OXTR-mediated Gαq signaling. This highlights the potential of ghrelin-targeted therapies to modulate oxytocinergic signaling with relevance for appetite regulation, anxiety, depression, and schizophrenia. Similarly, evidence for 5-HT2AR-OXTR heteromerization in the pyramidal cell layer of CA2 and CA3 in the dorsal hippocampus and in the nucleus accumbens shell was demonstrated. This complex may offer new strategies for the treatment of both mental disease and social behavior. Finally, the 5-HT2CR-OXTR heterocomplexes were demonstrated in the CA1, CA2, and CA3 regions of the dorsal hippocampus. Future work should be done to investigate the precise functional consequence of region-specific OXTR heteromerization in the brain, as well across the periphery, and whether the integration of neuronal signals in the brain may also involve higher order OXTR-GHS-R1a heteroreceptor complexes including the dopamine (DA), noradrenaline (NA) or serotonin (5-HT) receptor protomers or other types of G-protein coupled receptors (GPCRs).
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Affiliation(s)
- Dasiel O. Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden,Receptomics and Brain Disorders Lab, Department of Human Physiology, Faculty of Medicine, University of Malaga, Málaga, Spain,Department of Biomolecular Science, Section of Morphology, Physiology and Environmental Biology, University of Urbino, Urbino, Italy,*Correspondence: Dasiel O. Borroto-Escuela Harriët Schellekens
| | - Cristina Cuesta-Marti
- APC Microbiome Ireland, University College CorkCork, Ireland,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Alexander Lopez-Salas
- Receptomics and Brain Disorders Lab, Department of Human Physiology, Faculty of Medicine, University of Malaga, Málaga, Spain
| | | | - Minerva Crespo-Ramírez
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Emiliano Tesoro-Cruz
- Unidad de Investigación Biomédica en Inmunología e Infectología, Hospital de Infectología, Centro Médico Nacional La Raza, IMSS, Ciudad de México, Mexico
| | | | - Miguel Perez de la Mora
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Harriët Schellekens
- APC Microbiome Ireland, University College CorkCork, Ireland,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland,*Correspondence: Dasiel O. Borroto-Escuela Harriët Schellekens
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Chruścicka B, Cowan CSM, Wallace Fitzsimons SE, Borroto-Escuela DO, Druelle CM, Stamou P, Bergmann CA, Dinan TG, Slattery DA, Fuxe K, Cryan JF, Schellekens H. Molecular, biochemical and behavioural evidence for a novel oxytocin receptor and serotonin 2C receptor heterocomplex. Neuropharmacology 2020; 183:108394. [PMID: 33188842 DOI: 10.1016/j.neuropharm.2020.108394] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/11/2020] [Accepted: 11/05/2020] [Indexed: 12/11/2022]
Abstract
The complexity of oxytocin-mediated functions is strongly associated with its modulatory effects on other neurotransmission systems, including the serotonin (5-hydroxytryptamine, 5-HT) system. Signalling between oxytocin (OT) and 5-HT has been demonstrated during neurodevelopment and in the regulation of specific emotion-based behaviours. It is suggested that crosstalk between neurotransmitters is driven by interaction between their specific receptors, particularly the oxytocin receptor (OTR) and the 5-hydroxytryptamine 2C receptor (5-HTR2C), but evidence for this and the downstream signalling consequences that follow are lacking. Considering the overlapping central expression profiles and shared involvement of OTR and 5-HTR2C in certain endocrine functions and behaviours, including eating behaviour, social interaction and locomotor activity, we investigated the existence of functionally active OTR/5-HTR2C heterocomplexes. Here, we demonstrate evidence for a potential physical interaction between OTR and 5-HTR2Cin vitro in a cellular expression system using flow cytometry-based FRET (fcFRET). We could recapitulate this finding under endogenous expression levels of both receptors via in silico analysis of single cell transcriptomic data and ex vivo proximity ligation assay (PLA). Next, we show that co-expression of the OTR/5-HTR2C pair resulted in a significant depletion of OTR-mediated Gαq-signalling and significant changes in receptor trafficking. Of note, attenuation of OTR-mediated downstream signalling was restored following pharmacological blockade of the 5-HTR2C. Finally, we demonstrated a functional relevance of this novel heterocomplex, in vivo, as 5-HTR2C antagonism increased OT-mediated hypoactivity in mice. Overall, we provide compelling evidence for the formation of functionally active OTR/5-HTR2C heterocomplexes, adding another level of complexity to OTR and 5-HTR2C signalling functionality. This article is part of the special issue on Neuropeptides.
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Affiliation(s)
- Barbara Chruścicka
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Małopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland
| | | | | | | | | | | | | | - Timothy G Dinan
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - David A Slattery
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Frankfurt, Germany
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - John F Cryan
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Harriët Schellekens
- APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
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Chruścicka B, Wallace Fitzsimons SE, Borroto-Escuela DO, Druelle C, Stamou P, Nally K, Dinan TG, Cryan JF, Fuxe K, Schellekens H. Attenuation of Oxytocin and Serotonin 2A Receptor Signaling through Novel Heteroreceptor Formation. ACS Chem Neurosci 2019; 10:3225-3240. [PMID: 31038917 DOI: 10.1021/acschemneuro.8b00665] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The oxytocin receptor (OTR) and the 5-hydroxytryptamine 2A receptor (5-HTR2A) are expressed in similar brain regions modulating central pathways critical for social and cognition-related behaviors. Signaling crosstalk between their endogenous ligands, oxytocin (OT) and serotonin (5-hydroxytryptamine, 5-HT), highlights the complex interplay between these two neurotransmitter systems and may be indicative of the formation of heteroreceptor complexes with subsequent downstream signaling changes. In this study, we assess the possible formation of OTR-5HTR2A heteromers in living cells and the functional downstream consequences of this receptor-receptor interaction. First, we demonstrated the existence of a physical interaction between the OTR and 5-HTR2A in vitro, using a flow cytometry-based FRET approach and confocal microscopy. Furthermore, we investigated the formation of this specific heteroreceptor complex ex vivo in the brain sections using the Proximity Ligation Assay (PLA). The OTR-5HTR2A heteroreceptor complexes were identified in limbic regions (including hippocampus, cingulate cortex, and nucleus accumbens), key regions associated with cognition and social-related behaviors. Next, functional cellular-based assays to assess the OTR-5HTR2A downstream signaling crosstalk showed a reduction in potency and efficacy of OT and OTR synthetic agonists, carbetocin and WAY267464, on OTR-mediated Gαq signaling. Similarly, the activation of 5-HTR2A by the endogenous agonist, 5-HT, also revealed attenuation in Gαq-mediated signaling. Finally, altered receptor trafficking within the cell was demonstrated, indicative of cotrafficking of the OTR/5-HTR2A pair. Overall, these results constitute a novel mechanism of specific interaction between the OT and 5-HT neurotransmitters via OTR-5HTR2A heteroreceptor formation and provide potential new therapeutic strategies in the treatment of social and cognition-related diseases.
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Affiliation(s)
- Barbara Chruścicka
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Shauna E. Wallace Fitzsimons
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Clémentine Druelle
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Kenneth Nally
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Timothy G. Dinan
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - John F. Cryan
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden
| | - Harriët Schellekens
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
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