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Hashizume T, Horiuchi M, Tate N, Nonaka S, Kojima M, Hosoda H, Kangawa K. Effects of ghrelin on growth hormone secretion from cultured adenohypophysial cells in cattle. Endocr J 2003; 50:289-95. [PMID: 12940457 DOI: 10.1507/endocrj.50.289] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To clarify the direct effects of ghrelin on growth hormone (GH) release from anterior pituitary (AP) cells in cattle, GH-releasing effects of human ghrelin (hGhrelin) and rat ghrelin (rGhrelin) on bovine AP cells were compared with those of GH-releasing hormone (GHRH) in vitro. The AP cells were obtained from Holstein steers and were incubated for 2 h with the peptides after incubating in DMEM for 3 days. hGhrelin and rGhrelin significantly stimulated GH release from the cultured cells at doses from 10(-10) to 10(-7) M and from 10(-9) to 10(-7) M, respectively (P<0.05). The rates of increase in GH at 10(-10), 10(-9), 10(-8) and 10(-7) M hGhrelin were 26, 26, 59 and 100% compared with controls, respectively, and those of increase in GH at 10(-9), 10(-8) and 10(-7) M rGhrelin were 58, 74 and 106%, respectively. GHRH significantly increased GH concentrations in cultured media at a dose as low as 10(-13) M compared with the control (P<0.05). When hGhrelin (10(-8) M) and GHRH (10(-8) M) were added together, the release of GH induced by both peptides was significantly greater than that by hGhrelin alone (P<0.05), and tended to be greater than that by GHRH alone. Somatostatin (SS, 10(-7) M) significantly blunted GH release induced by hGhrelin (10(-8) M) and GHRH (10(-8) M) (P<0.05). In the presence of SS, the percent increase in GH released with hGhrelin plus GHRH was 42% and 14% greater than that by either hGhrelin or GHRH alone, respectively (P<0.05). These results show that ghrelin directly stimulates the release of GH from anterior pituitary cells, and that SS modifies ghrelin-stimulated GH release in cattle.
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Affiliation(s)
- Tsutomu Hashizume
- Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
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Mogi K, Li JY, Suzuki M, Sawasaki T, Takahashi M, Nishihara M. Characterization of GH pulsatility in male Shiba goats: effects of postpubertal castration and KP102. Endocr J 2002; 49:145-51. [PMID: 12081232 DOI: 10.1507/endocrj.49.145] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The present study was conducted in order to characterize the secretory pattern of GH in the Shiba goat, a native Japanese miniature goat, and to examine the effects of castration and KP102, a GH secretagogue, on this pattern. Blood samples were taken from an indwelling jugular catheter every 15 min for 24 h, and plasma GH was measured by radioimmunoassay. In intact males, GH was secreted in a pulsatile manner with very regular 5-h periodicity, which consisted of a distinctive GH pulse and a trough of virtually no GH secretion. Postpubertal castration increased the height and decreased the width of GH pulses, though it did not affect the interpulse interval and area under the curve. Modification of the shape of each GH pulse by testicular androgen might play a role in the expression of GH action in the male. KP102 (10 microg/kg, i.v.) immediately induced a robust GH pulse, which was followed by a spontaneous GH pulse of normal characteristics at regular intervals, suggesting that the clock generating GH pulses was reset by KP102. From these observations, we concluded that the Shiba goat is a very suitable experimental model for elucidating the mechanisms underlying GH pulse generation, and in particular, the involvement of androgen and GH secretagogues.
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Affiliation(s)
- Kazutaka Mogi
- Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Japan
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Phung LT, Sasaki A, Lee HG, Vega RA, Matsunaga N, Hidaka S, Kuwayama H, Hidari H. Effects of the administration of growth hormone-releasing peptide-2 (GHRP-2) orally by gavage and in feed on growth hormone release in swine. Domest Anim Endocrinol 2001; 20:9-19. [PMID: 11164330 DOI: 10.1016/s0739-7240(00)00085-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The experiments were conducted to determine the effects of the administration of growth hormone-releasing peptide-2 (GHRP-2, also named KP102), both orally by gavage and in feed, on the release of growth hormone (GH) in swine and to investigate whether attenuation of the GH response occurs after short-term treatment with the peptide in feed. In the first experiment, saline or GHRP-2 at doses of 1, 4.5 and 9 mg/kg body weight (BW) was dissolved in 15 ml saline and administered orally as a bolus by gavage to cross-bred castrated male swine (n = 6). Orally administered GHRP-2 stimulated dose-related increases in peak concentrations of GH, with a return to basal by 120 min. After administering GHRP-2 orally, peak concentrations of GH and areas under the GH response curves (GH AUCs) for 180 min were higher (P < 0.05) than those in saline controls. In Experiment 2, GHRP-2 at doses of 0 (served as control), 1, 4.5 and 9 mg/kg BW was mixed in 150 g of feed and offered to cross-bred castrated male swine (n = 6) at 0900 hr and 1700 hr daily for a 3-d period. Administration of 1 mg/kg BW GHRP-2 to swine in feed failed to stimulate the release of GH, but GHRP-2 at doses of 4.5 and 9 mg/kg BW significantly (P < 0.05) increased plasma concentrations of GH after initial and final treatments at 0900 hr on Days 1 and 3 of treatment, respectively. Peak concentrations of GH and GH AUCs for 180 min after the initial and final treatments in the 4.5 and 9 mg/kg BW GHRP-2-treated swine were higher (P < 0.05) than those in controls. After 3 d of treatment with GHRP-2 in feed at doses of 4.5 and 9 mg/kg BW, GH responses to the peptide were maintained. The results of the present study indicate that the administration of GHRP-2 orally by gavage and in feed stimulates the release of GH in swine, and that the GH-releasing effect of the peptide does not become desensitized after short-term administration in feed.
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Affiliation(s)
- L T Phung
- Laboratory of Animal Production, Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Nishi, Inada-cho, Obihiro 080-8555, Japan
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Hashizume T, Tanabe Y, Ohtsuki K, Mori A, Matsumoto N, Hara S. Plasma growth hormone (GH) responses after administration of the peptidergic GH secretagogue KP102 into the oral cavity, rumen, abomasum and duodenum in adult goats. Domest Anim Endocrinol 2001; 20:37-46. [PMID: 11164332 DOI: 10.1016/s0739-7240(00)00087-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The study was performed to determine whether orally administered KP102 (also known as GHRP-2) stimulates GH release in adult goats, and how the orally administered KP102 passes through the digestive tract and stimulates GH release in ruminant animals. Five mg/kg body weight (BW) of KP102 dissolved in 9 ml of saline were administered into the oral cavity, rumen, omasum and duodenum of adult goats, and GH release after administration of KP102 was examined. The GH levels were significantly elevated at 20 min after administration of KP102 into the oral cavity, and plasma concentrations of GH remained significantly elevated until 60 min (P < 0.05). The GH levels after administration of KP102 into the abomasum were variable. However, the GH level tended to increase within 30 min after administration, and were significantly higher than those of controls after 120 to 150 min (P < 0.05). The GH levels after administration of KP102 into the duodenum were significantly elevated at 40 min after administration, and plasma concentrations of GH remained significantly elevated until 140 min (P < 0.05). The administration of KP102 into the rumen failed to stimulate GH release. The GH response curves (AUC) produced after administration of KP102 into the abomasum or duodenum were 2.2-fold greater than those for after administration into the oral cavity (P < 0.05). The oral administration of 5 mg/kg BW of KP102 in the powder state, not dissolved in 9 ml of saline, failed to stimulate GH release. These results suggested that orally administered KP102 dissolved in saline transiently stimulates GH release in adult goats, and this phenomenon might be due to small amounts of the peptides entering directly into the abomasum with liquid bypassing the rumen.
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Affiliation(s)
- T Hashizume
- Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan.
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Phung LT, Inoue H, Nou V, Lee HG, Vega RA, Matsunaga N, Hidaka S, Kuwayama H, Hidari H. The effects of growth hormone-releasing peptide-2 (GHRP-2) on the release of growth hormone and growth performance in swine. Domest Anim Endocrinol 2000; 18:279-91. [PMID: 10793268 DOI: 10.1016/s0739-7240(00)00050-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The effects of GHRP-2 (also named KP102), a new growth hormone-releasing peptide, on the release of growth hormone (GH) and growth performance were examined in swine. The single intravenous (i. v.) injection of GHRP-2 at doses of 2, 10, 30 and 100 microg/kg body weight (BW) to cross-bred castrated male swine stimulated GH release in a dose-dependent manner, with a return to the baseline by 120 min. The peak GH concentrations and GH areas under the response curves (GH AUCs) for 180 min after the injections of GHRP-2 were higher (P < 0.05) than those after the injection of saline. The GH responses to repeated i.v. injections of GHRP-2 (30 microg/kg BW) at 2-h intervals for 6 h were decreased after each injection. The chronic subcutaneous (s.c.) administration of GHRP-2 (30 microg/kg BW) once daily for 30 days consistently stimulated GH release. The GH AUCs for 300 min after the injections on d 1, 10 and 30 of treatment in GHRP-2-treated swine were higher than those in saline-treated swine. However, chronic administration of GHRP-2 caused a partial attenuation of GH response between d 1 and 10 of treatment. The chronic s.c. administration of GHRP-2 also increased average daily gain for the entire treatment period by 22.35% (P < 0.05) and feed efficiency (feed/gain) by 20.64% (P < 0.01) over the saline control values, but did not significantly affect daily feed intake. These results indicate that GHRP-2 stimulates GH release and enhancing growth performance in swine.
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Affiliation(s)
- L T Phung
- Laboratory of Animal Production, Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Nishi, Inada-cho, Obihiro, Japan
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Hashizume T, Takahashi Y, Numata M, Sasaki K, Ueno K, Ohtsuki K, Ishii A. Plasma Profiles of Growth Hormone, Prolactin and Insulin-like Growth Factor-I during Gestation, Lactation and the Neonatal Period in Goats. J Reprod Dev 1999. [DOI: 10.1262/jrd.45.273] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Tsutomu Hashizume
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
| | - Yuuko Takahashi
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
| | - Megumi Numata
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
| | - Koichi Sasaki
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
| | - Kimiko Ueno
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
| | - Kenji Ohtsuki
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
| | - Aya Ishii
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan
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Hashizume T, Kawai M, Ohtsuki K, Ishii A, Numata M. Oral administration of peptidergic growth hormone (GH) secretagogue KP102 stimulates GH release in goats. Domest Anim Endocrinol 1999; 16:31-9. [PMID: 10081661 DOI: 10.1016/s0739-7240(98)00048-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To assess the oral activity of KP102 (also known GHRP-2) on growth hormone (GH) release in ruminant animals, 5 or 10 mg/kg body weight (BW) of KP102 dissolved in saline was orally administered twice at 2 hr-intervals to either 1- or 3-mo-old goats (n = 5-6). Plasma GH concentrations in the 1-mo-old goats were elevated at 15 min after the first administration of both 5 and 10 mg/kg BW of KP102. Significant elevation of GH concentrations continued until 180 min after 10 mg/kg BW of KP102, whereas the elevated GH levels after the administrations of 5 mg/kg BW of KP102 subsided to basal concentrations within 90 min. The second administration of 10 mg/kg BW of KP102 failed to elevate the GH concentration, but 5 mg/kg BW of KP102 abruptly stimulated GH release. Plasma GH concentrations in the 3-mo-old goats were also significantly elevated after the administration of both 5 and 10 mg/kg BW of KP102. The plasma GH responses to 5 and 10 mg/kg BW of KP102 were almost identical. The elevated GH levels after the first administration of KP102 tended to be maintained throughout the experiment, and a transient increase in plasma GH levels was observed after the second administration. However, the stimulatory effect of KP102 on GH release in the 3-mo-old goats was small and less abrupt than that in the 1-mo-old goats. The concentrations of insulin-like growth factor-I were not increased by KP102 during the brief sampling periods used in this experiment. These results show that the oral administration of the peptidergic GH secretogogue KP102 stimulates GH release in a ruminant species, and that the oral activity of KP102 on GH release is modified by the age.
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Affiliation(s)
- T Hashizume
- Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Morioka, Japan.
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