Involvement of the orexin system in sympathetic nerve regulation

Manabu Murakami, Takayoshi Ohba, Testuya Kushikata, Hidetoshi Niwa, Akira Kurose, Tadaatsu Imaizumi, Hiroyuki Watanabe, Teruyuki Yanagisawa, Shigeyuki Nakaji, Kyoichi Ono, Kazuyoshi Hirota

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Orexin, also known as hypocretin, is a secreted neuropeptide implicated in the regulation of sleep and food intake. In the present study, we examined the importance of orexin in regulation of the sympathetic nervous system using an orexin/ataxin-3 transgenic (OXTg) rat, which has a minimal number of orexin neurons. RT-PCR analysis identified expression of prepro-orexin and orexin receptor-1 (OX1R) in the superior cervical ganglion (SCG), and expression of another receptor (OX2R) was marginal in the wild-type rat. The orexin/ataxin-3 transgenic rat showed increased expression of OX1R and OX2R, whereas expression of prepro-orexin was undetectable, suggesting a compensatory increase in both receptors. In the ECG recording (R-R interval), orexin/ataxin-3 transgenic rats showed decreased responsiveness to the β-adrenergic blocker propranolol. Furthermore, OXTg rats had deteriorated R-R interval regulation, indicating involvement of the orexin system in sympathetic nerve regulation. This was accompanied by decreased baroreflex and responsiveness to β-adrenergic blocker in blood pressure recording, also suggesting involvement of the orexin system in sympathetic nerve regulation. Histological examination revealed hypotrophic changes in the transgenic heart, suggesting involvement of the orexin system in cardiac development. Taken together, our present results indicate involvement of the orexin system in sympathetic nerve control.

Original languageEnglish
Pages (from-to)1076-1081
Number of pages6
JournalBiochemical and biophysical research communications
Volume460
Issue number4
DOIs
Publication statusPublished - 2015 May 12

Keywords

  • ECG
  • Orexin
  • Rat
  • Sympathetic nerve

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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