Chronic central infusion of orexin-A increases arterial pressure in rats.
We determined the cardiovascular responses as well as food and water intakes to chronic intracerebroventricular administration of orexin-A and orexin-B for 14 days in conscious rats. Chronic intracerebroventricular infusion of orexin-A (50 pmol/h) elicited a significant increase in systolic blood pressure on the third day (+15.6 +/- 2.9 mm Hg), and during the continuous intracerebroventricular infusion of orexin-A the blood pressure returned to the baseline levels at day 14. In contrast, chronic intracerebroventricular infusion of orexin-B (50 pmol/h) failed to change systolic blood pressure during the 14 days of experimental periods. Chronic intracerebroventricular infusions of neither orexin-A nor orexin-B changed urinary catecholamine excretions, food and water intakes, and urine volumes at 7 and 14 days of infusion periods. Mean arterial pressure directly measured at 14 days did not differ among the groups of orexin-A, orexin-B, and artificial cerebrospinal fluid treatments. Both intravenous injections of pentolinium (5 mg/kg), a ganglion blocking agent, and CV-11974 (0.05 mg/kg), an AT(1) receptor antagonist, decreased arterial pressure; however, these responses were not different among the groups. These results suggest that central orexin-A participates in the short-term regulation of blood pressure; however, the contributions of central orexins to the long-term regulations of blood pressure, sympathetic nervous system, and appetite may be little.
Lin
Yingzi
Y
Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan.
Matsumura
Kiyoshi
K
Tsuchihashi
Takuya
T
Abe
Isao
I
Iida
Mitsuo
M
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology; D001713:Biphenyl Compounds; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism / Q000494:pharmacology*; D002395:Catecholamines / Q000652:urine; D004326:Drinking / Q000187:drug effects* / Q000502:physiology; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology; D007276:Injections, Intraventricular; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009479:Neuropeptides / Q000378:metabolism / Q000494:pharmacology*; D000068797:Orexins; D010425:Pentolinium Tartrate / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012084:Renin-Angiotensin System / Q000187:drug effects* / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D013777:Tetrazoles / Q000494:pharmacology
D000959:Antihypertensive Agents; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D002352:Carrier Proteins; D002395:Catecholamines; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D013777:Tetrazoles; D010425:Pentolinium Tartrate; C081643:candesartan