Characteristics of Growth Hormone Secretion Responsiveness to Growth Hormone-Releasing Peptide-2 (GHRP-2 or KP102) in Calves

• Published in: ENDOCRINE JOURNAL Vol. 43; no. 3; pp. 291 - 298
• Main Authors: ROH, SANG-GUN, MATSUNAGA, NOBUYOSHI, HIDAKA, SATOSHI, HIDARI, HISASHI
• Format: Journal Article
• Language: English
• Published: Japan The Japan Endocrine Society 1996
• Subjects: Animal Husbandry - methods; Animals; Blood Glucose - drug effects; Blood Glucose - metabolism; Calf; Cattle - growth & development; Cattle - metabolism; Dose-Response Relationship, Drug; Eating - drug effects; Eating - physiology; Fatty Acids, Nonesterified - blood; Fatty Acids, Nonesterified - metabolism; GH-releasing peptide-2; Growth Hormone - blood; Growth Hormone - drug effects; Growth Hormone - metabolism; Growth Hormone-Releasing Hormone - pharmacology; Hormones - pharmacology; Infusion Pumps - veterinary; Injections, Intravenous - veterinary; Insulin-Like Growth Factor I - drug effects; Insulin-Like Growth Factor I - metabolism; Male; Oligopeptides - administration & dosage; Oligopeptides - pharmacology; Periodicity; Weight Gain - drug effects; Weight Gain - physiology
• ISSN: 0918-8959; 1348-4540
• DOI: 10.1507/endocrj.43.291

This study was conducted to determine the effects of acute and chronic administration of GH-releasing peptide-2 (D-AIa-D-βNal-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 25.0μg/kg body weight (BW) of KP102. The GH AUC (area under curve, ng/ml•min, mean±SEM) for 60min was significantly increased with 6.25 (676.3±125.6), 12.5 (1574.8± 318.0) and 25.0 (1578.7±214.6)μg/kgBW of KP102 than with saline (78.6±36.1) (P<0.01). GH responses were decreased by multiple injections of 12.5μg/kgBW KP102 at every 2h for 8h. 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 12.5μg/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.