GHRP-6对培养的垂体生长激素腺瘤和正常胚胎垂体细胞促GH分泌特征

The Effects of GH Releasing Peptide-6(GHRP-6) on GH Secretion of Human Pituitary Somatotrophinoma and Embryo Pituitary Cells in Vitro

目的 研究人工合成的生长激素释放剂GHRP 6对体外培养的人垂体生长激素腺瘤细胞GH分泌影响 ,并分析其可能的临床意义。方法 用原代细胞培养技术 ,观察了 6例垂体GH腺瘤细胞和 4例正常胚胎垂体细胞对GHRP 6、生长释放激素 (GH releasinghormone,GHRH)和生长抑素 (somatostatin ,SS)的体外分泌效应。 结果 GHRP 6对所有 6例GH腺瘤细胞GH分泌表现出明显的刺激效应 (P <0 0 1) ,但远不如正常垂体细胞敏感 ,但GH腺瘤细胞对持续的GHRP 6刺激反应时间延长。GHRH和SS仅对部分GH腺瘤细胞有作用 ,且SS不能完全阻断GHRP 6对于GH分泌的刺激效应。结论 GH腺瘤细胞对于体外GHRP 6持续刺激的异常反应 ,表明垂体GH腺瘤中可能存在GH释放剂受体 (GHS R)所固有的负反馈机制———“脱敏”机制的减弱 。

Objective to observe the effects of GH releasing peptide-6(GHRP-6) on GH secretion of human pituitary somatotrophinoma cells in vitro.Methods The response to GHRP-6,GH-releasing hormone(GHRH) and somatostatin(SS) in 6 somatotrophinomas and 3 embryo pituitaries in vitro were observed.Results In vitro cell culture,a stimulatory response to GHRP-6 was found in both groups of somatotrophinomas,and excitative effects is not as more sensitive as normal pituitary.Howerer,the GH response time to repeated administration of GHRP-6 to somatotrophinomas was prolonged.The GH-secreting effects of GHRH or SS was only obtained in parts of somatotrophinomas.Moreover,SS only attenuation but abolished GH response to GHRP-6.Conclusion The abnormal response to repeated administration of GHRP-6 in vitro showed that the lack of desensition-negative feedback loops of GH releasing hormone receptors was associated with tumorigenesis of GH secreting adenomas.