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In this study we demonstrate: (i) The GnRH agonist exerts a direct dose-dependet stimulative effect on the aromatase activity and progesterone production in cultured monkey granulosa cells; (ii)the stimulative effect on steroidogenesis can be completely blocked by concomitant treatment with a GnRH antagonist, suggesting that the actions of GnRH are mediated through stringent stereospecific recongnition sites; (iii) in addition to the stimulative effect, the GnRH agonist in the presence of gonadotropins also exerts an inhibitory effect, even though the peptide by itself is more effective in the stimulation of steroidogenesis, and the stimulation of gonadotropin on steroidogenesis could be gradually restored by decreasing the concentration of the GnRH agonist in the culture; and (iv) paradoxical effect can also be observed in the presence of cAMP-inducing agents, suggesting that the inhibitory action of the peptide on gonadotropin-induced steroidogenesis is localized at a step distal to the stringent reco 相似文献
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实验证明:(1)促性腺激素释放激素类似物(GnRHa)刺激猴颗粒细胞芳香化酶活性和孕酮产生,并与剂量有直接关系;(2)GnRH拮抗物能完全阻断GnRHa的作用,表明GnRHa是通过颗粒细胞表面受体对其甾体形成起作用的;(3)除刺激作用外,GnRHa与促性腺激素一起则抑制雌激素和孕酮的产生;降低GnRHa的含量可逐渐恢复促性腺激素对甾体形成的刺激作用;(4)GnRHa对颗粒细胞的双向作用在cAMP诱导剂存在下也可观察到,这说明GnRHa抑制促性腺激素诱导甾体激素的形成是发生在受体结合以后的信息传递系统的某个部位上。 相似文献
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从眼镜蛇(Najanajaatra)毒中纯化出膜毒素MT-Ⅰ,该毒素与磷脂酶A2产生协同溶血效应,使小鸡颈二腹肌等标本产生进行性挛缩,对体外Hut-78细胞有杀伤作用,腹腔注射能引起家猫的心电图异常 相似文献
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在农业生产和野外工作中常可遇到毒蛇咬伤,对劳动人民健康有很大危害。对蛇伤的治疗,本文提出了一种新的局部注射胰蛋白酶的有效方法。实验表明,在给小鼠和狗皮下注射致死量的眼镜蛇科蛇毒以后,15分钟内局部注射胰蛋白酶,实验动物全都存活下来,且不致出现全身性的中毒症状。在注毒20—50分钟后给酶,也可以有50—90%的小鼠免于死亡。即使在蛇咬后已经过相当长的时间,注射胰蛋白酶也可以破坏咬伤部位组织中积存的蛇毒。胰蛋白酶的制造比较容易,保存也不需要特殊的条件,并可装在随身携带的急救自动注射器中,因此用胰蛋白酶比用抗蛇毒血清治疗的优点要多。 相似文献
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