title: Involvement of the orexin system in sympathetic nerve regulation.
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.
authors: Department of Pharmacology, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan. Electronic address: mmura0123@hotmail.co.jp.
authors: Manabu
authors: M
authors: Murakami
authors: Department of Cellphysiology, Akita University Graduate School of Medicine, Akita, 010-8543, Japan.
authors: Takayoshi
authors: T
authors: Ohba
authors: Department of Anesthesiology, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
authors: Testuya
authors: T
authors: Kushikata
authors: Department of Anesthesiology, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
authors: Hidetoshi
authors: H
authors: Niwa
authors: Department of Anatomic Pathology, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
authors: Akira
authors: A
authors: Kurose
authors: Department of Vascular Biology, Institute of Brain Science, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
authors: Tadaatsu
authors: T
authors: Imaizumi
authors: Department of Internal Medicine Division of Cardiovascular and Respiratory Medicine, Akita University Graduate School of Medicine, Akita, 010-8543, Japan.
authors: Hiroyuki
authors: H
authors: Watanabe
authors: Department of Molecular Pharmacology, Tohoku University School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai, 980-8578, Japan.
authors: Teruyuki
authors: T
authors: Yanagisawa
authors: Social Medicine, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
authors: Shigeyuki
authors: S
authors: Nakaji
authors: Department of Cellphysiology, Akita University Graduate School of Medicine, Akita, 010-8543, Japan.
authors: Kyoichi
authors: K
authors: Ono
authors: Department of Anesthesiology, Hirosaki University, Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
authors: Kazuyoshi
authors: K
authors: Hirota
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004562:Electrocardiography; D020869:Gene Expression Profiling; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D009479:Neuropeptides / Q000235:genetics / Q000502:physiology*; D000068797:Orexins; D051381:Rats; D055647:Rats, Transgenic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins
keywords: ECG; Orexin; Rat; Sympathetic nerve