Localization of angiotensin II in pig ovary and its effects on oocyte maturation in vitro.

The renin-angiotensin system (RAS) has been found in mammalian ovarian tissue; however, its physiological role is unclear. This study examined the content of angiotensin II (Ang II) in porcine follicular fluid (pFF), Ang II localization and its receptors in ovary, and the effects of Ang II on porcine oocyte maturation. The concentrations of Ang II were 6951.82 +/- 1295.83, 3502.99 +/- 679.10, 3147.89 +/- 690.60, and 2545.92 +/- 407.01 pg/ml in pFF from small, medium, large, and extra-large follicles, respectively. In addition, Ang II was found on zona pellucidae (ZP) and granulosa cells by immunoreactive staining. The distribution of AT1, an Ang II receptor subtype, was in accordance with that of Ang II. However, AT2, another Ang II receptor, was mainly distributed in the stroma and thecal layers of follicles. When oocytes were cultured in media containing various concentrations of Ang II, a higher (P<0.05) proportion of oocytes reached metaphase II (MII) in the medium with 100 ng/ml (87.0%) than without Ang II (61%). When oocytes from different sizes of follicles were separately cultured in media containing 100 ng/ml Ang II, maturation rates were significantly higher in oocytes from small (61.5%) and medium (85.1%) follicles than that of their controls (45.1 and 72.6%, respectively). However, addition of Ang II inhibited nuclear maturation in oocytes from large follicles (77.8% versus 87.3%). Fertilization and male pronuclear (MPN) formation rates of oocytes matured in medium containing 100 or 1000 ng/ml of Ang II were higher (P<0.05) than that of oocytes matured in medium containing 0 or 10 ng/ml Ang II. Glutathione content in oocytes cultured for 44 h in medium containing 100 or 1000 ng/ml of Ang II was also higher (P<0.01) than that of oocytes cultured in medium containing 0 or 10 ng/ml Ang II. In conclusion, Ang II was present in porcine ovaries and may regulate follicle growth and oocyte maturation.

[Modulation of prolactin (PRL) secretion in human uterine decidual cells at early pregnancy].

Decidualization is essential for implantation of embryo and maintenance of pregnancy in human. The mechanism of decidualization was investigated in this study by regulation of prolactin (PRL) release in cultured human decidual cells during first trimester of gestation. Progesterone significantly stimulated PRL secretion, but the effect of estrogen depended on its concentration, which was ineffective at the physiological level (10( 9) mol/L) but suppressed the stimulatory effect of progesterone at higher levels. Thus adequate proportion of estrogen and progesterone is important for the decidualization. Furthermore, RU486 dramatically inhibited PRL release, suggesting that the effect of progesterone was mediated, at least in part, through its receptor. cAMP at concentration higher than 10( 5) mol/L significantly increased PRL secretion, suggesting that the cAMP signal pathway might be involved in decidualization.

[Tissue concentration and secretion of renin in human placental villi during early pregnancy].

In this study, tissue concentrations of renin and angiotensins in human placental villi during early pregnancy and contents of renin and angiotensin I (A I) secreted by cultured chorion were measured by radioimmunal assay (RIA). The results are as follows. During early pregnancy, the human chorion contains renin and A II. The activity of renin is much higher at 6th week of gestation, but as gestation proceeds, it decreases gradually, while A II shows somewhat increased change. The activity of renin secreted by cultured chorion can also be measured. A I in human placental villi can not be detected by RIA in chorion leaves or their culturing fluid. These results indicate that renin-angiotensin system may exist independently in human placental villi during early pregnancy.