Nestoron (Segesterone Acetate), a synthetic progestin, is a high-affinity agonist of the progesterone receptor (EC50: 10.3 nM).

PR:10.3 nM

Nestorone (ST-1435) 与小牛胸腺GR的结合显示出显著性（ED50 = 56 nM）。黄体酮和Nestorone 对SHBG无结合作用[1]。长期使用ST-1435和E2单独或联合均可相似程度地增加神经元生成，ST-1435与E2之间最小至无拮抗或增效作用。此外，长期暴露于ST-1435或ST-1435 + E2 刺激了少突胶质细胞的生成[2]。

Nestorone在皮下给药时的效力是口服途径的100倍以上。Nestorone没有表现出雄激素或阳离子活性，并且不与性激素结合球蛋白(SHBG)结合。与雌二醇和左炔诺孕酮不同，Nestorone在卵巢切除的大鼠中没有显示出子宫促进活性。尽管Nestorone显著地与糖皮质激素受体(GR)结合，但在体内没有表现出糖皮质激素活性[1]。

Immature female rats were ovariectomized under methoxylflurane anesthesia, randomly distributed into treatment groups (n 5 6 per group), and used 5 to 7 days later. Levonorgestrel or Nestorone (1 or 5 mg) was injected s.c. daily for 5 days. Vaginal lavages were examined microscopically to detect vaginal cornification. The animals were killed on day 6, and the uteri were removed, cleaned, blotted dry, and weighed. The antiestrogenic effects of levonorgestrel and Nestorone were determined in rats receiving 1.0 mg E2. A positive control group received E2 alone. Negative controls received the vehicle [1].