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EFFECTS OF PGE_2 AND PGF_(2α) ON PLASMINOGEN ACTIVATOR ACTIVITY IN RAT GRANULOSA CELLS

Lu Yen-ling and Xu He-sheng (Shanghai Institute of Cell Biology,Academia Sinica)  
Two main parts are included in this work; 1.Activity of Plasminogen Activator (PA) after prostaglandin synthesis being inhibited in vivo or in vitro by indomethacin was de-termined.For in vivo experiments,26-27 days old wistar female rats primed by PMSG and then HCG,and simultaneously treated with indomethacin at doses of being capable to block ovulation,were used.Granulosa cells from preovulatory follicles of those primed rats were cultured.In order to avoid the in-domethacin metabolized in vivo,in vitro tests were taken.Immature rats were only primed by PMSG,and granulosa cells from thus trea-ted animals were subjected to administrations of indomethacin at concentrations from 10~(-8)M to 10~(-5)M.The culture medium,which con-tained PA secreted from granulosa cells,was directly determined by the iodinated fibrin plate assay.Both in in vivo and in vitro ex-periments,the PA activity showed no signifi-cant decrease as compared with that of con-trols (Fig,1,2).2.Effects of PGE_2 and PGF_(2α) on granulosa cell PA activity were observed.Granulosa cells obtained from rats primed only with PMSG were cultured either with PGE_2 or PGF_(2α) at the same concentra-tions as those of indomethacin mentioned abo-ve.The PA activity is stimulated by the PGE (Fig.3),whereas no effect has been shown with PGF_(2α) (Fig.4).Fig.5 and 6 exhibit that the response to PGE_2 is time- and dose-dependent.When the concentration of PGE_2 was at 10~(-6)M,the PA activity not only rea-ched its maximum but also showed a similar value as compared with the control which was treated with HCG instead of PGE_2 (Fig.3).Follicular cells obtained from rats without any prior hormonal treatment also showed remar-kable response to PGE_2,even a higher activi-ty was noted when compared with those pre-viously primed by PMSG (Fig.5,6). Two conclusions can be drawn from our experimental results: 1.Besides the PGE_2 having the mimic effect to LH on stimulating the PA activity,it has the similar effect as FSH on immature follicular cells.2.Due to the phenomenon that a slight increase of PA activity was noted in in vitro experiment,we assume that,if PGE_2 was at a physiological dose,the decrease of PA activity produced by the indirect inhibition of indomethacin in vivo may be masked by the effective influences of PMSG and HCG containing high quantity of FSH or LH respectively,and the latter hor-mones are known with strong stimulation to PA activity of granulosa cell.
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