维甲酸、地塞米松和生长激素释放激素联合诱导生长激素细胞分化

目的探讨维甲酸(RA)、地塞米松(Dex)和生长激素释放激素(GHRH)在诱导生长激素(GH)细胞分化中的作用。方法原代培养大鼠胚胎垂体细胞,将RA(10-6mol/L)、Dex(50 nmol/L)和GHRH(10-7mol/L)单独或联合应用6 d,诱导大鼠胚胎垂体细胞分化,利用免疫组化检测GH阳性细胞百分比,放射免疫分析检测培养液的上清液中GH含量。结果与对照组相比,单独应用RA显著增加GH阳性细胞的百分比和GH的含量(P<0.05),而单独应用Dex和GHRH均无此作用(P>0.05);RA诱导4 d后,再加入Dex诱导2 d,其诱导效应较单独应用RA明显增强(P<0.05),而加入GHRH则不起作用(P>0.05);RA和Dex联合诱导4 d后,再加入GHRH诱导2 d,其诱导效应较RA和Dex联合诱导明显增强(P<0.01)。结论RA能够促进GH细胞的早期分化,Dex和GHRH则不能;RA能够与Dex、GHRH发挥协同效应,诱导GH细胞分化。

Retinoic acid, dexamethason and growth hormone releasing hormone induce differentiation of fetal rat somatotroph in vitro

Objective To study effects of retinoic acid(RA),dexamethason(Dex) and/or growth hormone releasing hormone(GHRH) on fetal somatotroph differentiation.Methods The pituitary cells derived from fetal rats were primarily cultured for 4 days in the culture fluid without any reagents(control group),and then they were continuously cultured again respectively in the culture fluid with RA,Dex,GHRH,RA+GHRH,RA+Dex and RA+Dex+GHRH from 2 to 6 days.The GH-positive cells rate in the cultured pituitary cells and GH content in the supernatant of the culture fluid were determined respectively by immunocytochimistry technique and radioimmunoassay.Results GH-positive cells rate and GH content were significantly higher in RA group and RA+GHRH group than those in the control group(P<0.05) which were insignificantly lower than that in Dex groups and GHRH group(P>0.05).The GH-positive cells rate and GH content were significantly higher in RA+Dex group and RA+Dex+GHRH group than those in RA and RA+GHRH groups 6 days after the culture(P<0.05).Conclusions The enhancement of samototroph differentiation in early fetal stage may be produced by RA,but not Dex and GHRH.The synergic effect of RA,Dex and GHRH on the somatotroph differentiation and GH secretion at the specific stages of embryonic development may be observed.