Interleukin-6 attenuates serotonin 2a receptor signaling by activating the JAK-STAT pathway

Mol Pharmacol. 2015;87(3):492-500. doi: 10.1124/mol.114.096289. Epub 2014 Dec 30.


The serotonin 2A (5-HT2A) receptor and the proinflammatory cytokine, interleukin-6 (IL-6), have both been implicated in psychiatric disorders. Previously, we demonstrated that these molecules both facilitate cognitive flexibility, a prefrontal cortex-mediated executive function impaired in multiple mental illnesses. In this study, we tested the hypothesis that IL-6 influences 5-HT2A receptor signaling, providing a potential mechanism by which this cytokine may influence behavior. We first demonstrated that 5-HT2A receptors and IL-6-mediated STAT3 phosphorylation colocalize in cells of the prefrontal cortex, providing the neuroanatomical substrate for a potential interaction. In the neuronally derived A1A1 cell line, which expresses both IL-6 and 5-HT2A receptors, we found that IL-6 attenuates inositol phosphate (IP) accumulation in response to the 5-HT2 agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI), suggesting that IL-6 can regulate 5-HT2A receptor function. To identify the signaling pathway(s) that mediate this effect, we measured DOI-mediated IP accumulation in the presence of IL-6 and either the JAK-STAT inhibitor 124 [(9β,10α,16α,23E)-2,16,20,25-tetrahydroxy-9-methyl-19-norlanosta-1,5,23-triene-3,11,22-trione], JSI-124, or the extracellular signal-regulated kinase inhibitor, 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD-98059). The IL-6 effect was blocked by JSI-124 but not PD-98059. Furthermore, silencing RNA knockdown of either JAK or STAT blocked the IL-6 effect, suggesting that IL-6-induced JAK-STAT activation can regulate 5-HT2A receptor signaling. Finally, to determine if IL-6 specifically regulates the 5-HT2A receptor system, we measured IP production mediated by another Gq-coupled receptor, bradykinin B2. IL-6 had no effect on bradykinin-mediated IP accumulation, suggesting that regulation may occur at the 5-HT2A receptor. These results may provide clues to the pathologic mechanisms underlying certain psychiatric disorders and may suggest novel therapeutic strategies for their treatment.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Enzyme Activation / drug effects
  • Enzyme Activation / physiology
  • Interleukin-6 / pharmacology*
  • Janus Kinases / metabolism*
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Serotonin, 5-HT2A / metabolism*
  • STAT Transcription Factors / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*


  • Interleukin-6
  • Receptor, Serotonin, 5-HT2A
  • STAT Transcription Factors
  • Janus Kinases