RT Journal Article T1 Molecular, biochemical and behavioural evidence for a novel oxytocin receptor and serotonin 2C receptor heterocomplex A1 Chruścicka, Barbara A1 Cowan, Caitlin S.M. A1 Wallace Fitzsimons, Shauna E. A1 Borroto Escuela, Dasiel Óscar A1 Druelle, Clémentine M. A1 Stamou, Panagiota A1 Bergmann, Cristian A. A1 Dinan, Timothy G. A1 Slattery, David A. A1 Fuxe, Kjell A1 Cryan, John F. A1 Schellekens, Harriët K1 Receptores de hormonas K1 Receptores celulares K1 Oxitocina K1 Serotonina AB 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-HTR2C in 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. PB Elsevier SN 00283908 YR 2021 FD 2021-02-01 LK https://hdl.handle.net/10630/45034 UL https://hdl.handle.net/10630/45034 LA eng NO Barbara Chruścicka, Caitlin S.M. Cowan, Shauna E. Wallace Fitzsimons, Dasiel O. Borroto-Escuela, Clémentine M. Druelle, Panagiota Stamou, Cristian A. Bergmann, Timothy G. Dinan, David A. Slattery, Kjell Fuxe, John F. Cryan, Harriët Schellekens, Molecular, biochemical and behavioural evidence for a novel oxytocin receptor and serotonin 2C receptor heterocomplex, Neuropharmacology, Volume 183, 2021, 108394, ISSN 0028-3908, https://doi.org/10.1016/j.neuropharm.2020.108394. (https://www.sciencedirect.com/science/article/pii/S0028390820304627) NO Science Foundation Ireland (SFI) NO National Science Centre (NCN, Poland) NO Swedish Medical Research Council (Sweden / Vetenskapsrådet) NO Hjärnfonden NO Karolinska Institutet Forskningsstiftelser NO Olle Engkvist Stiftelse DS RIUMA. Repositorio Institucional de la Universidad de Málaga RD 27 feb 2026