Evidence that growth hormone exerts a feedback effect on stomach ghrelin production and secretion.
Ghrelin is a recently discovered stomach hormone that stimulates pituitary growth hormone (GH) secretion potently. The purpose of these experiments was to test the hypothesis that a stomach-ghrelin-pituitary-GH axis exists in which either an elevation or reduction in systemic GH levels will exert a negative or positive feedback action, respectively, on stomach ghrelin homeostasis. In rats, GH administration decreased stomach ghrelin mRNA levels and plasma ghrelin levels significantly. In GH-releasing hormone (GHRH) transgenic mice, GHRH overexpression decreased stomach ghrelin peptide levels when compared with control mice. In aged rats (25 months) stomach ghrelin mRNA and peptide levels and plasma ghrelin levels were decreased when compared with young rats (5 months). Because GH secretion is reduced in aged rats, the elevated stomach ghrelin production and secretion may reflect a decreased GH feedback on stomach ghrelin, homeostasis, and secretion. Together, these findings suggest that endogenous pituitary GH exerts a feedback action on stomach ghrelin homeostasis and support the hypothesis that a stomach-ghrelin-pituitary GH axis exists.
Qi
Xiang
X
Department of Surgery, University of Texas Medical Branch, Galveston, Texas 77555, USA.
Reed
Jason
J
Englander
Ella W
EW
Chandrashekar
Varadaraj
V
Bartke
Andrzej
A
Greeley
George H
GH
D000367:Age Factors; D000818:Animals; D015152:Blotting, Northern; D025461:Feedback, Physiological; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism*; D054439:Ghrelin; D013006:Growth Hormone / Q000494:pharmacology*; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D036361:Peptide Hormones / Q000096:biosynthesis* / Q000097:blood / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley
D054439:Ghrelin; D036361:Peptide Hormones; D012333:RNA, Messenger; D012313:RNA; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone