P2X2R purinergic receptor subunit mRNA and protein are expressed by all hypothalamic hypocretin/orexin neurons

Fulvio Florenzano, Maria Teresa Viscomi, Valentina Mercaldo, Patrizia Longone, Giorgio Bernardi, Claudia Bagni, Marco Molinari, Pascal Carrive

Research output: Contribution to journalArticlepeer-review


Neurophysiologic data suggest that orexin neurons are directly excited by ATP through purinergic receptors (P2XR). Anatomical studies, though reporting P2XR in the hypothalamus, did not describe it in the perifornical hypothalamic area, where orexinergic neurons are located. Here we report the presence of the P2X2R subunit in the rat perifornical hypothalamus and demonstrate that hypothalamic orexin neurons express the P2X2R. Double immunohistochemistry showed that virtually all orexin-immunoreactive neurons are also P2X2R immunoreactive, whereas 80% of P2X2R- immunoreactive neurons are also orexin positive. Triple-labeling experiments, combining fluorescence in situ hybridization for P2X2R mRNA and P2X2R/orexin double immunofluorescence, confirmed these findings. In addition, in situ hybridization demonstrated that P2X2R mRNA is localized in cellular processes of orexinergic neurons. The present data support neurophysiologic findings on ATP modulation of orexinergic function and provide direct evidence that the entire population of orexin neurons expresses a P2XR subtype, namely, P2X2R. Thus, purinergic transmission might intervene in modulating key functions known to be controlled by the orexinergic system, such as feeding behavior and arousal.

Original languageEnglish
Pages (from-to)58-67
Number of pages10
JournalJournal of Comparative Neurology
Issue number1
Publication statusPublished - Sep 1 2006


  • ATP receptors
  • Autonomic regulation
  • Eating disorders
  • mRNA localization
  • Perifornical hypothalamus
  • Sleep-wake cycle

ASJC Scopus subject areas

  • Neuroscience(all)


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