Soliman E B, Hashizume T, Kanematsu S
Laboratory of Animal Reproduction, Faculty of Agriculture, Iwate University, Morioka, Japan.
Endocr J. 1994 Oct;41(5):585-91. doi: 10.1507/endocrj.41.585.
The effect of His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (GHRP) on growth hormone (GH) release from cultured bovine anterior pituitary (AP) cells was studied in vitro with the interactive effects of GH-releasing factor (GRF: hpGRF (1-29)-NH2) and somatostatin (SRIF). The AP cells (5 x 10(4) cells per well) were incubated with media, and the media were changed 3 days after plating. After 3.5 days in culture, cells were incubated for 2 h with the peptides. GHRP stimulated GH release from cultured cells in a dose-related manner. At doses from 10(-11) to 10(-7) M GHRP, the amount of GH released was significantly greater than the controls (P < 0.05 to P < 0.001). The amounts of GH released at lower doses of GHRP (10(-14) to 10(-12) M) were not significantly different from the controls. GH concentrations after treatment with 10(-11) and 10(-7) M GHRP were 3.98 +/- 0.27 and 4.81 +/- 0.16 ng/ml, respectively. In experiments performed similarly, the 10(-7) M GHRH, GHRP, and combined treatment with GHRP plus GHRH increased GH 126, 57, and 139%, respectively (P < 0.001). The GH releasing effects of either GHRH alone or GHRP plus GHRH were significantly more potent than that of GHRP alone (P < 0.001). The additive effect was not significant when compared with GHRH alone. GH release induced by either GHRH or GHRP was significantly inhibited by SRIF (P < 0.01) compared with the untreated control. The inhibitory effect of SRIF in combined treatment with GHRP plus GHRH was significantly less than that of SRIF with GHRH or with GHRP (P < 0.01). The present study suggests that GH-releasing peptide (GHRP) induced GH release in cattle via a direct action on anterior pituitary cells in vitro.
在体外研究了His-D-Trp-Ala-Trp-D-Phe-Lys-NH2（生长激素释放肽，GHRP）对培养的牛垂体前叶（AP）细胞生长激素（GH）释放的影响，以及生长激素释放因子（GRF：人垂体生长激素释放因子（1-29）-NH2）和生长抑素（SRIF）的相互作用。将AP细胞（每孔5×10⁴个细胞）接种于培养基中培养，接种3天后更换培养基。培养3.5天后，用这些肽孵育细胞2小时。GHRP以剂量相关的方式刺激培养细胞释放GH。在10⁻¹¹至10⁻⁷M的GHRP剂量下，释放的GH量显著高于对照组（P<0.05至P<0.001）。较低剂量GHRP（10⁻¹⁴至10⁻¹²M）释放的GH量与对照组无显著差异。用10⁻¹¹和10⁻⁷M GHRP处理后的GH浓度分别为3.98±0.27和4.81±0.16 ng/ml。在类似实验中，10⁻⁷M生长激素释放激素（GHRH）、GHRP以及GHRP加GHRH联合处理分别使GH增加了126%、57%和139%（P<0.001）。单独使用GHRH或GHRP加GHRH的GH释放作用均显著强于单独使用GHRP（P<0.001）。与单独使用GHRH相比，相加效应不显著。与未处理的对照组相比，GHRH或GHRP诱导的GH释放均被SRIF显著抑制（P<0.01）。SRIF在GHRP加GHRH联合处理中的抑制作用显著小于其在GHRH或GHRP单独处理中的抑制作用（P<0.01）。本研究表明，生长激素释放肽（GHRP）在体外通过直接作用于牛垂体前叶细胞诱导GH释放。
