Pharmacological evidence for transactivation within melatonin MT2 and serotonin 5‐HT2C receptor heteromers in mouse brain

Romain Gerbier, Delphine Ndiaye‐Lobry, Pablo Blanco Martinez de Morentin, Erika Cecon, Lora Heisler, Philippe Delagrange, Florence Gbahou , Ralf Jockers* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Association of G protein‐coupled receptors into heterodimeric complexes has been reported for over 50 receptor pairs in vitro but functional in vivo validation remains a challenge. Our recent in vitro studies defined the functional fingerprint of heteromers composed of Gi‐coupled melatonin MT2 receptors and Gq‐coupled serotonin 5‐HT2C receptors, in which melatonin transactivates phospholipase C (PLC) through 5‐HT2C. Here, we identified this functional fingerprint in the mouse brain. Gq protein activation was probed by [35S]GTPγS incorporation followed by Gq immunoprecipitation, and PLC activation by determining the inositol phosphate levels in brain lysates of animals previously treated with melatonin. Melatonin concentration‐dependently activated Gq proteins and PLC in the hypothalamus and cerebellum but not in cortex. These effects were inhibited by the 5‐HT2C receptor‐specific inverse agonist SB‐243213, and were absent in MT2 and 5‐HT2C knockout mice, fully recapitulating previous in vitro data and indicating the involvement of MT2/5‐HT2C heteromers. The antidepressant agomelatine had a similar effect than melatonin when applied alone but blocked the melatonin‐promoted Gq activation due to its 5‐HT2C antagonistic component. Collectively, we provide strong functional evidence for the existence of MT2/5‐HT2C heteromeric complexes in mouse brain. These heteromers might participate in the in vivo effects of agomelatine.

Original languageEnglish
Article numbere21161
Number of pages12
JournalThe FASEB Journal
Issue number1
Early online date6 Nov 2020
Publication statusPublished - Jan 2021

Bibliographical note

The authors are grateful to E. Trinquet (Cisbio) for advice in the in vivo IP1 protocol. This work was supported by grants from the Fondation Recherche Médicale (Equipe FRM2013, DEQ 20130326503 and Equipe FRM 2019, EQU201903008055 to RJ); The French National Research Agency (ANR) ANR-19-CE16-0025-01 (Mito-GPCR) to RJ, Recherches Partenariales et Innovation Biomédicale 2012 “MED-HET-REC-2”; INSERM; CNRS and the Who am I? laboratory of excellence ANR-11-LABX- 0071 funded by the French Government through its “Investments for the Future” program operated by the ANR under Grant ANR-11-IDEX-0005-01; La Ligue Contre le Cancer N/Ref: RS19/75-127 and the Biotechnology and Biological Sciences Research Council (BB/R01857X/1 and BB/N017838/1 to LKH).

Data Availability Statement

Additional Supporting Information may be found online in the Supporting Information section.


  • cerebellum
  • GPCR heteromerization
  • hypothalamus
  • melatonin receptor
  • receptor transactivation
  • 5-HT2C
  • 5-HT
  • melatonin receptors


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