Molecular Neurobiology

, Volume 29, Issue 1, pp 31–39

Multiple signal transduction pathways mediated by 5-HT receptors

  • Mami Noda
  • Haruhiro Higashida
  • Shunsuke Aoki
  • Keiji Wada
Article

DOI: 10.1385/MN:29:1:31

Cite this article as:
Noda, M., Higashida, H., Aoki, S. et al. Mol Neurobiol (2004) 29: 31. doi:10.1385/MN:29:1:31

Abstract

Among human serotonin (5-HT) receptor subtypes, each G protein-coupled receptor subtype is reported to have one G protein-signaling cascade. However, the signaling may not be as simple as previously thought to be. 5-HT5A receptors are probably the least well understood among the 5-HT receptors, but the authors found that 5-HT5A receptors couple to multiple signaling cascades. When the 5-HT5A receptors were expressed in undifferentiated C6 glioma cells, they modulated the level of second messengers. For example, activation of 5-HT5A receptors inhibited the adenylyl cyclase activity and subsequently reduced the cAMP level, as previously reported. In addition to this known signaling via Gi/Go, 5-HT5A receptors are coupled to the inhibition of ADP-ribosyl cyclase and cyclic ADP ribose formation. On the other hand, activation of 5-HT5A receptors transiently opened the K+ channels, presumably due to the increase in intracellular Ca2+ after formation of inositol (1,4,5) trisphosphate. The K+ currents were inhibited by both heparin and pretreatment with pertussis toxin, suggesting the cross-talk between Gi/Go protein and phopholipase C cascade. Thus, the authors results indicate that 5-HT5A receptors couple to multiple second messenger systems and may contribute to the complicated physiological and pathophysiological states. Although this multiple signaling has been reported only for 5-HT5A/5-HT1 receptors so far, it is possible that other 5-HT receptor subtypes bear similar complexity. As a result, in addition to the wide variety of expression patterns of each 5-HT receptor subtype, it is possible that multiple signal transduction systems may add complexity to the serotonergic system in brain function. The investigation of these serotonergic signaling and its impairment at cellular level may help to understand the symptoms of brain diseases.

Index Entries

5-HT5A receptorsGi/Goadenylyl cyclasecyclic AMPADP ribosyl cyclasecyclic ADP riboseIP3K+ channels

Copyright information

© Humana Press Inc. 2004

Authors and Affiliations

  • Mami Noda
    • 1
  • Haruhiro Higashida
    • 2
  • Shunsuke Aoki
    • 3
  • Keiji Wada
    • 3
  1. 1.Laboratory of PathophysiologyKyushu University Graduate School of Pharmaceutical SciencesFukuoka
  2. 2.Department of Biophysical GeneticsKanazawa University Graduate School of MedicineKanazawa
  3. 3.Department of Degenerative Neurological DiseasesNational Institute of Neuroscience, National Center of Neurology and PsychiatryKodaira, TokyoJapan