Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9894479 | Regulatory Peptides | 2005 | 5 Pages |
Abstract
Ghrelin, a novel endogenous growth hormone (GH) secretagogue, has been shown to exert very potent and specific GH-releasing activity in rats and humans. However, little is known about its GH-releasing activity and endocrine effects in domestic animals. To clarify the effect of ghrelin on GH secretion in vivo in ruminants, plasma GH responses to intra-arterial and intra-hypothalamic injections of rat ghrelin (rGhrelin) were examined in goats and cattle. The intra-arterial injection of 1 μg/kg BW of rGhrelin in ovariectomized goats failed to stimulate GH release, however, a dosage of 3 μg/kg BW significantly increased plasma GH concentrations (P<0.05). GH levels peaked at 15 min after the injection, then decreased to basal concentrations within 1 h after the injection. However, the secretory response to 3 μg/kg BW of rGhrelin was weaker than that of growth hormone-releasing hormone (GHRH) (0.25 μg/kg BW) (P<0.05). An infusion of 10 nmol of ghrelin into the medial basal hypothalamus (arcuate nucleus) significantly stimulated the release of GH in male calves (P<0.05). GH levels began to rise just after the infusions and peaked at 10 min, then decreased to the basal concentrations within 1 h after the injection. The present results show that ghrelin stimulates GH release in ruminants.
Related Topics
Life Sciences
Biochemistry, Genetics and Molecular Biology
Biochemistry
Authors
Tsutomu Hashizume, Mami Horiuchi, Sumie Nonaka, Etsuko Kasuya, Masayasu Kojima, Hiroshi Hosoda, Kenji Kangawa,