Cella S G, Locatelli V, Poratelli M, De Gennaro Colonna V, Imbimbo B P, Deghenghi R, Müller E E
University of Milan, Department of Pharmacology, Italy.
Peptides. 1995;16(1):81-6. doi: 10.1016/0196-9781(94)00149-z.
The GH-releasing activity of hexarelin was evaluated in unanesthetized young and aged dogs. Hexarelin (15.6-250 micrograms/kg, i.v.) significantly stimulated GH secretion in a dose-dependent fashion in dogs of both age groups. The ability of hexarelin to potentiate the GH-releasing effect of GHRH (2 micrograms/kg, i.v) and clonidine (4 micrograms/kg, i.v.) was then tested. Hexarelin strikingly potentiated the effect of GHRH both in young and aged dogs, whereas it potentiated the effect of clonidine in young dogs only. Because clonidine acts on the hypothalamus to release GHRH, its failure to synergize with hexarelin in aged dogs is likely due to an age-related impairment of GHRH-secreting neurons.
在未麻醉的年轻和老年犬中评估了六肽生长激素释放肽（hexarelin）的生长激素释放活性。六肽生长激素释放肽（15.6 - 250微克/千克，静脉注射）以剂量依赖方式显著刺激了两个年龄组犬的生长激素分泌。随后测试了六肽生长激素释放肽增强生长激素释放激素（GHRH，2微克/千克，静脉注射）和可乐定（4微克/千克，静脉注射）的生长激素释放作用的能力。六肽生长激素释放肽在年轻和老年犬中均显著增强了生长激素释放激素的作用，而仅在年轻犬中增强了可乐定的作用。由于可乐定作用于下丘脑以释放生长激素释放激素，其在老年犬中未能与六肽生长激素释放肽协同作用可能是由于与年龄相关的生长激素释放激素分泌神经元功能受损。
