Department of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.
Department of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.
Theriogenology. 2017 Jul 1;96:126-135. doi: 10.1016/j.theriogenology.2017.04.014. Epub 2017 Apr 7.
Apelin was thought to be an adipocyte-specific hormone, but recent studies indicate a link between apelin and female reproductive function. Using real-time PCR, immunoblotting, immunohistochemistry and ELISA, we demonstrated expression of apelin and its receptor (APJ) in ovarian follicles of different sizes from mature pigs. Apelin concentration in the follicular fluid, and expression of both apelin and APJ, increased with follicular growth; greatest values were found in large follicles. Immunohistochemistry revealed the positive staining for apelin and APJ in membranes of granulosa, than theca cells. Furthermore, we observed strong expression of apelin in oocytes and APJ in the zona pellucida. The effect of apelin (0.02, 0.2, 2 and 20 ng/ml) on basal and IGF1- and FSH-induced steroid hormone (progesterone [P4], and estradiol [E2]) secretion, steroidogenic enzyme (3βHSD and CYP19A1) expression and cell proliferation (Alamar blue) was determined. Apelin was found to increase basal steroid secretion, but decrease IGF1- and FSH-induced steroid secretion, and 3βHSD and CYP19 expression. Apelin also increased cell proliferation and the phosphorylation level of 5'-monophosphate-activated protein kinase (AMPK), phosphatidyl inositol 3' kinase/Akt (Akt) and extracellular signal-regulated kinases (ERK1/2). AMPKα was involved in the action of apelin in P4 production, and MAPK/ERK and Akt/PI3 mediated the proliferative effect of apelin. However, these effects on steroid secretion and cell proliferation were abolished when cultured in the presence of ML221, an APJ antagonist. In conclusion, apelin appears to regulate ovarian follicular functions such as steroidogenesis and proliferation via APJ activation and different signaling pathways.
Apelin 被认为是一种脂肪细胞特异性激素，但最近的研究表明 Apelin 与女性生殖功能之间存在联系。我们使用实时 PCR、免疫印迹、免疫组织化学和 ELISA 方法，证明了 Apelin 及其受体（APJ）在不同大小的成熟猪卵巢卵泡中的表达。卵泡液中的 Apelin 浓度以及 Apelin 和 APJ 的表达均随卵泡生长而增加；在大卵泡中达到最大值。免疫组织化学显示 Apelin 和 APJ 在颗粒细胞和膜上呈阳性染色，而在膜上呈阳性染色。此外，我们观察到 Apelin 在卵母细胞中以及在透明带中表达强烈的 APJ。Apelin（0.02、0.2、2 和 20 ng/ml）对基础和 IGF1 和 FSH 诱导的类固醇激素（孕酮[P4]和雌二醇[E2]）分泌、类固醇生成酶（3βHSD 和 CYP19A1）表达和细胞增殖（Alamar blue）的影响。发现 Apelin 增加基础类固醇分泌，但减少 IGF1 和 FSH 诱导的类固醇分泌以及 3βHSD 和 CYP19 表达。Apelin 还增加细胞增殖和 5'-单磷酸激活蛋白激酶（AMPK）、磷脂酰肌醇 3'激酶/Akt（Akt）和细胞外信号调节激酶（ERK1/2）的磷酸化水平。AMPKα 参与 Apelin 在 P4 产生中的作用，而 MAPK/ERK 和 Akt/PI3 介导 Apelin 的增殖作用。然而，当在 APJ 拮抗剂 ML221 的存在下培养时，这些对类固醇分泌和细胞增殖的影响被消除。总之，Apelin 似乎通过 APJ 激活和不同的信号通路调节卵巢卵泡功能，如类固醇生成和增殖。
