Effect of chronic treatments with ghrelin on milk secretion in lactating rats.
Ghrelin, a novel acylated peptide and endogenous ligand for growth hormone (GH) secretagogue receptor, was originally isolated from rat and human stomachs. In addition to its GH-releasing activity, ghrelin plays an important role in many physiological functions, including food intake, gastric acid secretion, neonatal development, and so on. In this study, the effect of daily treatment with ghrelin on milk production was investigated in lactating rats and the development of the pups was monitored. Daily subcutaneous injection of ghrelin into nursing dams for 8 days from parturition caused a significant increase in milk yield and litter weight gain. When litters nursed by ghrelin-treated and saline-treated dams were interchanged on day 4 of lactation, the growth curves were reversed. Daily injections of ghrelin also increased plasma GH levels. Northern blot analysis revealed that daily injection of ghrelin significantly increased mammary casein mRNA expression. In addition, RT-PCR analysis showed that a ghrelin receptor was present in the mammary glands of lactating rats. These results suggest that ghrelin may play an important role in milk production in lactating dams.
Nakahara
Keiko
K
Department of Veterinary Physiology, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2155, Japan.
Hayashida
Takahiro
T
Nakazato
Masamitsu
M
Kojima
Masayasu
M
Hosoda
Hiroshi
H
Kangawa
Kenji
K
Murakami
Noboru
N
D000818:Animals; D002364:Caseins / Q000235:genetics; D005260:Female; D054439:Ghrelin; D013006:Growth Hormone / Q000097:blood; D007774:Lactation / Q000187:drug effects* / Q000502:physiology; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000502:physiology; D008892:Milk / Q000378:metabolism*; D036361:Peptide Hormones / Q000008:administration & dosage*; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002364:Caseins; D054439:Ghrelin; D036361:Peptide Hormones; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D013006:Growth Hormone