Abstract：
Porcine spermatozoa are stored in the oviductal isthmus after natural mating, and the number of spermatozoa is increased in the oviductal ampulla when the mature cumulus-oocyte complexes (COCs) are transferred into the ampulla. However, the mechanism is unclear. Herein, natriuretic peptide type C (NPPC) was mainly expressed in porcine ampullary epithelial cells, whereas its cognate receptor natriuretic peptide receptor 2 (NPR2) was located on the neck and the midpiece of porcine spermatozoa. NPPC increased sperm motility and intracellular Ca2+ levels, and induced sperm release from oviduct isthmic cell aggregates. These actions of NPPC were blocked by the cyclic guanosine monophosphate (cGMP)-sensitive cyclic nucleotide-gated (CNG) channel inhibitor l-cis-Diltiazem. Moreover, porcine COCs acquired the ability to promote NPPC expression in the ampullary epithelial cells when the immature COCs were induced to maturation by epidermal growth factor (EGF). Simultaneously, transforming growth factor-β ligand 1 (TGFB1) levels were dramatically increased in the cumulus cells of the mature COCs. The addition of TGFB1 promoted NPPC expression in the ampullary epithelial cells, and the mature COC-induced NPPC was blocked by the transforming growth factor-β type 1 receptor (TGFBR1) inhibitor SD208. Taken together, the mature COCs promote NPPC expression in the ampullae via TGF-β signaling, and NPPC is required for the release of porcine spermatozoa from the oviduct isthmic cells.
摘要：
自然交配后，猪精子储存在输卵管峡部，当成熟的卵丘-卵母细胞复合物（COCs）转移到壶腹时，输卵管壶腹的精子数量增加。然而,机制尚不清楚。在这里，利钠肽C型(NPPC)主要表达于猪壶腹上皮细胞,而其同源受体利钠肽受体2（NPR2）位于猪精子的颈部和中部。NPPC增加精子活力和细胞内Ca2+水平，并诱导精子从输卵管峡部细胞聚集体中释放。NPPC的这些作用被环磷酸鸟苷（cGMP）敏感的环核苷酸门控（CNG）通道抑制剂1-顺式-地尔硫卓阻断。此外，当表皮生长因子（EGF）诱导未成熟的COCs成熟时，猪COCs获得了促进壶腹上皮细胞中NPPC表达的能力。同时,在成熟COC的卵丘细胞中，转化生长因子-β配体1（TGFB1）的水平显着增加。TGFB1的添加促进壶腹上皮细胞中NPPC的表达，成熟的COC诱导的NPPC被转化生长因子β1型受体（TGFBR1）抑制剂SD208阻断。一起来看,成熟的COCs通过TGF-β信号促进壶腹NPPC表达，从输卵管峡部细胞释放猪精子需要NPPC。
