GRP和VIP对E_2诱致的垂体催乳素(PRL)瘤细胞PRL基因转录的影响

THE EFFECTS OF GASTRIN-RELEASING PEPTIDE(GRP)AND VASOACTIVE INTESTINAL POLYPEPTIDE(VIP)ON THE PROLACTIN(PRL)GENE TRANSCRIPTION OF PITUTITARY PRL RELEASING TUMOR OF RAT

实验应用雄性SD大鼠，皮下埋植内置10mg雌二醇（E2）硅胶管3个月致垂体催乳素（prolactin，PRL）瘤后，取PRL瘤细胞进行体外原代培养，并应用原位杂交方法，研究不同剂量的胃泌素释放肽（gastrin－releasingpeptide，GRP）和血管活性肠肽（vasoactiveintestinalpolypeptide，VIP）以及E2对离体培养的垂体PRL瘤细胞PRL基因转录的影响。结果如下：GRP，VIP分别与PRL瘤细胞孵育24h后，10－8mol／L，10－7mol／L的GRP均不影响PRL瘤细胞内PRLmRNA水平，但10-6mol／L的GRP可使胞内PRLmRNA水平下降20％（P＜0．05）。在本实验所采用的浓度范围内，VIP均可升高PRL瘤细胞内PRLmRNA水平，10－8mol／L，10－7mol／L，10－6mol／L的VIP分别使胞内PRLmRNA升高为对照组的1．60，2．10，2．21倍（P＜0．05）。三种浓度的E2分别与PRL瘤细胞孵育48h后，10－8mol／LE2不影响胞内PRLmRNA水平，但10－7mol／L，10－6mol／L的E2则分别可使胞内PRLmRNA升高为对照组的2．80，2．92倍（P＜0．05）。上述结果表明：GRP和VIP可能分别抑制和增强由E2诱致的垂体PRL瘤细胞PRL基因的转录；一定浓度的E2可能直接涉及E2诱发垂体PRL瘤时伴高PRL血症。

The effects of gastrin-releasing peptide (GRP) and vasoactive intestinal polypeptide (VIP) on the prolactin gene transcription of cultured pituitary of male SpragueDawley (SD) rats PRL releasing tumor (PPRT) (induced by estradiol) cells were studied. The PRL mRNA levels were determined by in situ hybridization of cytoplasmicRNA with a DIG-labeled PRL cDNA probe. PRL mRNA levels didn＇t change when thePPRT cells were incubated with 10-8 mol/L or 10-7 mol/L GRP for 24 h, but decreased by 20% when GRP was increased t0 1O-6 mol/L (P＜0.05). The PRL mRNA level increased t0 1. 60, 2. 10, 2. 21 times of the control group when the PPRTcells were respectively incubated with 10-8, 10-7, 10-6 mol/L VIP for 24 h (P＜0. 05). The PRL mRNA level didn＇t change when the PPRT tumor cells were incubated with 10-8 mol/L E2 for 48 h, but did increase to 2. 80 and 2. 92 times of the controlgroup respectively when 10-7 mol/L and 10-6 mol/L E2 were used. The results aboveindicated that GRP and VIP exert an inhibitory and a stimulatory effect on RPL genetranscription respectively, while the stimulatory action of E2 on PRL secretion is a direct one.