Characteristics of growth hormone secretion responsiveness to growth hormone-releasing peptide-2 (GHRP-2 or KP102) in calves.
This study was conducted to determine the effects of acute and chronic administration of GH-releasing peptide-2 (D-Ala-D-beta Nal-Ala-Trp-D-Phe-Lys-NH2, GHRP-2 or KP102) on GH responsiveness in male Holstein calves. In the dose response study of acute administration, six calves were injected iv with saline or 6.25, 12.5 and 25.0 micrograms/kg body weight (BW) of KP102. The GH AUC (area under curve, ng/ml.min, mean +/- SEM) for 60 min was significantly increased with 6.25 (676.3 +/- 125.6), 12.5 (1574.8 +/- 318.0) and 25.0 (1578.7 +/- 214.6) micrograms/kgBW of KP102 than with saline (78.6 +/- 36.1) (P < 0.01). GH responses were decreased by multiple injections of 12.5 micrograms/kgBW KP102 at every 2 h for 8 h. The GH AUC for 60 min was decreased from the first injection (1162.9 +/- 313.3) to the second injection (604.7 +/- 131.9), but the response was significantly higher for the first and second injections than the third (304.4 +/- 173.1) and fourth injections (320.7 +/- 144.2) (P < 0.05). In the chronic administration, 8 calves were implanted subcutaneously with osmotic pumps (Alzet pump). Each of the 4 calves was given with 12.5 micrograms/kgBW per hour KP102 and the other 4 calves served as the control. During the 14 day period, average daily gain was significantly increased (36.4%) over the control (P < 0.05). Food efficiency was not significant, but numerically higher (29.4%) than the control. The plasma GH concentration was not increased by chronic administration of KP102, but IGF-I appeared to increase in KP102-treated calves more than the control. These results suggest that the synthetic KP102 can be used for enhancing the growth performance in domestic animals.
Roh
S G
SG
Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, Japan.
Matsunaga
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N
Hidaka
S
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Hidari
H
H
D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D002417:Cattle / Q000254:growth & development / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood* / Q000187:drug effects / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006728:Hormones / Q000494:pharmacology*; D007260:Infusion Pumps / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D010507:Periodicity; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D006728:Hormones; D009842:Oligopeptides; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; C091874:growth hormone-releasing peptide-2