Rak Agnieszka, Szczepankiewicz Dawid, Gregoraszczuk Ewa Łucja
Department of Physiology and Toxicology of Reproduction, Chair of Animal Physiology, Institute of Zoology, Jagiellonian University, Kraków, Poland.
Growth Horm IGF Res. 2009 Feb;19(1):68-76. doi: 10.1016/j.ghir.2008.08.006. Epub 2008 Sep 21.
Recently, we reported stimulatory effect of ghrelin alone and in combination with growth hormone (GH) on estradiol secretion, aromatase activity in parallel with inhibitory effect on cell apoptosis. The aim of this study was to analyze the expression of the functional ghrelin receptor (GHS-R type 1a) and the effect of GH on GHSR-1a expression in cultured whole porcine follicles. Using RT-PCR and Western Blots, we demonstrated the presence of GHSR-1a in prepubertal pig ovary and found no influence of GH on either GHSR-1a protein levels or mRNA expression. Additionally, to show if, noted previously by us action of ghrelin on ovarian follicular function is dependent of its binding to GHSR-1a, we used an antagonist of the ghrelin receptor, (D-Lys-3)-GHRP-6. In cultures treated together ghrelin and (D-Lys-3)-GHRP-6, estradiol secretion, aromatase activity and cell proliferation returned to control levels. Inhibitory action on caspase-3 activity was not reversed by a selective antagonist of GHSR-1a. In conclusion, results of the present data clearly showed: (1) the presence of GHSR-1a in prepubertal pig ovary and found no influence of GH on GHSR-1a protein levels and mRNA expression, and (2) ghrelin effect on estradiol secretion, aromatase activity and cell proliferation dependent of its binding to GHSR-1a, while the effect on cellular apoptosis was independent of its binding to GHSR-1a.
最近，我们报道了胃饥饿素单独以及与生长激素（GH）联合使用时对雌二醇分泌、芳香化酶活性的刺激作用，同时还有对细胞凋亡的抑制作用。本研究的目的是分析功能性胃饥饿素受体（1a型生长激素促分泌素受体，GHS-R）的表达，以及GH对培养的整个猪卵泡中GHSR-1a表达的影响。通过逆转录聚合酶链反应（RT-PCR）和蛋白质免疫印迹法，我们证实了1a型生长激素促分泌素受体（GHSR-1a）在青春期前猪卵巢中的存在，并且发现GH对GHSR-1a蛋白水平或信使核糖核酸（mRNA）表达均无影响。此外，为了验证我们之前所指出的胃饥饿素对卵巢卵泡功能的作用是否依赖于其与GHSR-1a的结合，我们使用了胃饥饿素受体拮抗剂（D-赖氨酸-3）-生长激素释放肽-6 [（D-Lys-3）-GHRP-6]。在同时用胃饥饿素和（D-Lys-3）-GHRP-6处理的培养物中，雌二醇分泌、芳香化酶活性和细胞增殖恢复到了对照水平。GHSR-1a的选择性拮抗剂并未逆转对半胱天冬酶-3（caspase-3）活性的抑制作用。总之，本研究数据的结果清楚地表明：（1）青春期前猪卵巢中存在GHSR-1a，且GH对GHSR-1a蛋白水平和mRNA表达无影响；（2）胃饥饿素对雌二醇分泌、芳香化酶活性和细胞增殖的作用依赖于其与GHSR-1a的结合，而对细胞凋亡的作用则不依赖于其与GHSR-1a的结合。
