Neuronal effects of orexins: relevant to sympathetic and cardiovascular functions.
Orexin A and B, also called hypocretin 1 and 2, were recently discovered in the hypothalamus. This organ, in which a number of neuropeptides have been demonstrated to stimulate or suppress food intake, is considered important for the regulation of appetite and energy homeostasis. Orexins were initially reported as a regulator of food intake. More recent reports suggest their possible important roles in the multiple functions of neuronal systems, such as narcolepsy, a sleep disorder. Orexins and their receptors are distributed in neural tissue and brain regions involved in the autonomic and neuroendocrine control. Functional studies have shown that these peptides evoke changes in cardiovascular and sympathetic responses. The data from our in vivo and in vitro studies suggest that the peptide acting on neurons in the hypothalamic paraventricular nucleus increases the cardiovascular responses. This review will focus on the neural effects of orexins and how these peptides may participate in the regulation of cardiovascular and sympathetic functions.
Shirasaka
Tetsuro
T
Department of Anesthesiology, Miyazaki Medical College, 5200 Kihara, Kiyotake, 889-1692, Miyazaki, Japan.
Kunitake
Takato
T
Takasaki
Mayumi
M
Kannan
Hiroshi
H
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D002352:Carrier Proteins / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology*; D000068797:Orexins; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects*
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins