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KMID : 0648420090140020146
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Journal of Korean Society of Pediatric Endocrinology
2009 Volume.14 No. 2 p.146 ~ p.153
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Study on the Reciprocal Interactions between Growth Hormone
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Lee Seong-Yong
Shin Choong-Ho
Yang Sei-Won
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Abstract
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Purpose: The aim of this study was to determine whether there is a feedback relationship between pituitary growth hormone (GH) and gastric ghrelin.
Methods: We intravenously administered 10 μg of either rat ghrelin or normal saline to adult male Sprague-Dawley rats and then measured the plasma GH levels and the mRNA expression levels of pituitary GH mRNA and hypothalamic GH-releasing hormone (GHRH) mRNA. Human GH (500 μg/kg, twice a day) or normal saline was subcutaneously administered to rats with or without food for 3 days. Thereafter, the plasma ghrelin levels and the ghrelin mRNA levels in the stomach were measured.
Results: The plasma GH levels increased more significantly in rats that were administered ghrelin than in controls (P?0.05). The mRNA levels of pituitary GH and hypothalamic GHRH were similar in the 2 groups. The plasma ghrelin levels and the stomach ghrelin mRNA levels were not affected by GH administration. Fasting significantly increased plasma ghrelin levels (P?0.05) and stomach ghrelin mRNA levels (P?0.05).
Conclusion: Exogenous ghrelin administration only stimulated GH secretion without stimulating the synthesis of GH and GHRH. The synthesis and secretion of ghrelin were not suppressed by exogenous GH administration. These findings indicate that there is no feedback relationship between pituitary GH and gastric ghrelin.
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KEYWORD
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Ghrelin, Growth hormone, Growth hormone releasing hormone
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