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Central ghrelin modulates sympathetic activity in conscious rabbits
Kiyoshi Matsumura1, Takuya Tsuchihashi, Koji Fujii
1Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. matsumk@intmed2.med.kyushu-u.ac.jp
Hypertension (Dallas, Tex. : 1979)
|November 2, 2002
Summary
Ghrelin, a stomach peptide, lowers blood pressure and heart rate when administered centrally. It also reduces sympathetic nerve activity and enhances baroreflex sensitivity in rabbits, indicating a role in cardiovascular regulation.
Area of Science:
- Cardiovascular Physiology
- Neuroendocrinology
Background:
- Ghrelin, an orexigenic peptide from the stomach, influences cardiovascular function.
- Previous studies suggest central nervous system involvement in ghrelin's hypotensive effects.
Purpose of the Study:
- To investigate the central effects of ghrelin on cardiovascular and sympathetic responses.
- To determine ghrelin's role in regulating sympathetic nerve activity and baroreflexes.
Main Methods:
- Administered ghrelin intravenously and intracerebroventricularly in conscious rabbits.
- Measured arterial pressure, heart rate, and renal sympathetic nerve activity.
- Assessed baroreflex sensitivity using renal sympathetic nerve activity and heart rate.
Main Results:
- Intracerebroventricular ghrelin decreased arterial pressure, heart rate, and renal sympathetic nerve activity.
- Peak depressor and sympathoinhibitory effects were observed post-central ghrelin administration.
- Central ghrelin augmented baroreflex sensitivities for both renal sympathetic nerve activity and heart rate.
Conclusions:
- Ghrelin acts centrally to reduce arterial pressure and sympathetic outflow.
- Central ghrelin plays a role in regulating kidney sympathetic nerve activity.
- Ghrelin modulates the baroreceptor reflex in conscious rabbits.