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Published on: September 18, 2014
Ghrelin acts at the nucleus of the solitary tract to decrease arterial pressure in rats.
Yingzi Lin1, Kiyoshi Matsumura, Masayo Fukuhara
1Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan.
Hypertension (Dallas, Tex. : 1979)
|March 3, 2004
Summary
Ghrelin, a stomach peptide, lowers blood pressure and sympathetic activity when acting in the brainstem nucleus of the solitary tract in rats. This effect is mediated by the growth hormone secretagogue receptor.
Area of Science:
- Cardiovascular Physiology
- Neuroendocrinology
- Autonomic Nervous System Regulation
Background:
- Ghrelin, an orexigenic peptide from the stomach, influences cardiovascular functions.
- Previous studies showed ghrelin administration decreases arterial pressure and sympathetic activity in rabbits.
Purpose of the Study:
- To investigate the role of ghrelin in the brainstem on cardiovascular responses in rats.
- To determine the specific brainstem nuclei involved in ghrelin's cardiovascular effects.
Main Methods:
- Unilateral microinjection of ghrelin into specific rat brainstem nuclei (nucleus of the solitary tract, area postrema, ventrolateral medulla).
- Measurement of mean arterial pressure, heart rate, and renal sympathetic nerve activity.
- Pharmacological blockade using pentolinium (ganglion blocker) and atropine sulfate (muscarinic antagonist).
- Immunohistochemical analysis for growth hormone secretagogue receptor expression.
Main Results:
- Microinjection of ghrelin into the nucleus of the solitary tract significantly decreased mean arterial pressure, heart rate, and renal sympathetic nerve activity.
- These cardiovascular effects were abolished by pentolinium but not by atropine sulfate.
- Ghrelin microinjection into the area postrema and ventrolateral medulla did not alter cardiovascular parameters.
- Growth hormone secretagogue receptors were found in the nucleus of the solitary tract and dorsal motor nucleus of the vagus.
Conclusions:
- Ghrelin acts within the nucleus of the solitary tract to suppress sympathetic activity and reduce arterial pressure in rats.
- The findings highlight the nucleus of the solitary tract as a key site for ghrelin's central cardiovascular regulation.
- The mechanism involves the growth hormone secretagogue receptor and likely a non-cholinergic pathway.
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