催乳素延缓hCG诱发大鼠排卵和下调纤溶酶原激活系统在卵巢中的表达

给幼龄大鼠注射10IU PMSG,48h后注射7IU hCG,或者hCG加不同剂量的催乳素(PRL).在不同时间取出卵巢,检查输卵管中卵子数和卵巢不同细胞中组织型纤溶酶原激活因子(tPA)和抑制因子(PAI-1)mRNA含量和活性.结果表明:PRL减少hCG诱发的排卵数并有明显剂量和时间抑制曲线.当hCG注射24h后,在两组动物输卵管的卵子数无明显差异.PRL同时抑制hCG所诱发的颗粒细胞tPA表达;与少匕相反PRL还能显著刺激膜一间质细胞PAI-1mRNA表达.上述实验结果表明,PRL只暂时延缓而不是完全抑制hCG诱发的大鼠排卵.上述作用可能是通过抑制纤溶酶激活系统在卵巢中的表达引起的.

Prolactin Delaying hCG - induced Ovulation and Down Regulating Plasminogen Activator System in Rat Ovary

Immature female rats were injected subcutaneously (sc) with 10 IU pregnant mare serum go-nadotropin (PMSG) to stimulate follicle growth, and 48 h later were followed by injection with 7 IU hCG or 7 IU hCG plus various doses of prolactin (PRL) 15 minutes before hCG injection. The ovaries were examined for the presence of ova , the level of tissue type plasminogen activator (tPA) and plasminogen activator inhibitor type - 1 (PAI - 1) mRNA and activities. PRL dose -dependently decreases ovulation number. The suppression of hCG - induced ovulation by PRL was time -dependent. After the hormone treatment for 24 h, the number of ova in the oviducts in hCG plus PRL - treated groups was not significantly different. PRL was also found to suppress hCG -induced tPA gene expression in granulose cells in a time -dependent manner. In contrast, the PAI - 1 mRNA in the theca -interstitial cells (TI) in the PRL treated groups was higher than that in the corresponding hCG - treated groups. The data provided here suggest that PRL tem-porsrily delays, but does not completely inhibit hCG -induced ovulation, which may be caused by a temporal suppression of PA - mediated proteolysis.