Hypotensive effects of neuromedin U microinjected into the cardiovascular-related region of the rat nucleus tractus solitarius.
Neuromedin U (NMU) is a brain-gut peptide with potent contractile effects on the uterus and smooth muscle. Intracerebroventricular injection of NMU reportedly decreased food intake and body-weight gain in the rat. We evaluated the effects of NMU delivered by microinjection into the rat nucleus tractus solitarius (NTS) on cardiovascular responses. At the concentrations used (5, 10 or 50 pmol), the intra-NTS injection of NMU in artificial cerebrospinal fluid produced a significant reduction in both the mean arterial pressure and heart rate. The hypotensive responses were dose dependent. Our findings suggest that NMU may act as a neurotransmitter or neuromodulative substance that causes excitation of neurons in the NTS and that it may play a role in cardiovascular regulation in vivo.
Tsubota
Yuji
Y
Department of Physiology, Wakayama Medical University, Wakayama City, Japan.
Kakimoto
Nobuyuki
N
Owada-Makabe
Kyoko
K
Yukawa
Kazunori
K
Liang
Xiang-Ming
XM
Mune
Masatoshi
M
Maeda
Masanobu
M
D000818:Animals; D002319:Cardiovascular System / Q000187:drug effects* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007022:Hypotension / Q000139:chemically induced* / Q000503:physiopathology; D008297:Male; D008845:Microinjections; D009479:Neuropeptides / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000187:drug effects* / Q000502:physiology
D009479:Neuropeptides; C056900:neuromedin U