title: Effects of intravenous ghrelin injection on plasma growth hormone, insulin and glucose concentrations in calves at weaning.
abstract: Ghrelin action, which stimulates growth hormone (GH) secretion, may alter during the weaning period in calves. Our objective was to compare the effects of intravenous ghrelin injection on plasma GH, insulin and glucose concentrations in calves around the weaning period. Four Holstein bull calves were fed whole milk and allowed free access to solid feeds, and weaned at 7 weeks of age. Measurements were performed at weeks 1, 2, 4, 6, 7, 9, 11 and 13, when calves were intravenously injected with ghrelin (1.0 μg/kg body weight (BW)) through a catheter, and jugular blood samples were obtained temporally relative to the injection time. Estimated digestible energy intake per metabolic BW transiently decreased at week 7 because of low solid intake immediately after weaning, and thereafter gradually increased. Plasma insulin and glucose concentrations were not affected by ghrelin injection at all ages. In contrast, plasma GH concentrations increased with ghrelin injection at all ages. The incremental area of GH at week 7 was greatest and significantly higher compared with weeks 2, 4, 6 and 9. This result suggests that nutrient insufficiency immediately after weaning enhances GH responsiveness to ghrelin.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8528, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Fukumori
authors.forename: Takako
authors.initials: T
authors.lastname: Mita
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Sugino
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Masayasu
authors.initials: M
authors.lastname: Kojima
authors.forename: Kenji
authors.initials: K
authors.lastname: Kangawa
authors.forename: Taketo
authors.initials: T
authors.lastname: Obitsu
authors.forename: Kohzo
authors.initials: K
authors.lastname: Taniguchi
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D001835:Body Weight; D002417:Cattle / Q000097:blood / Q000502:physiology*; D054439:Ghrelin / Q000008:administration & dosage* / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D007275:Injections, Intravenous; D007328:Insulin / Q000097:blood*; D008297:Male; D014886:Weaning
chemical_list: D001786:Blood Glucose; D054439:Ghrelin; D007328:Insulin; D013006:Growth Hormone