Angiopoietin expression in ovine corpora lutea during the luteal phase: Effects of nutrition, arginine and follicle stimulating hormone.

The aim of this study was to evaluate angiopoietin (ANGPT) 1 and 2, and tyrosine-protein kinase receptor 2 (TIE2) expression in the corpora lutea (CL) of FSH-treated, or non-treated sheep administered arginine (Arg) or vehicle (saline, Sal), and fed a control (C), excess (O) or restricted (U) diet. Ewes from each dietary group were treated with Arg or Sal (experiment 1), and with FSH (experiment 2). Luteal tissues were collected at the early-, mid- and/or late-luteal phases of the estrous cycle. Protein and mRNA expression was determined using immunohistochemistry followed by image analysis, and quantitative RT-PCR, respectively. The results demonstrated that ANGPT1 and TIE2 proteins were localized to luteal capillaries and endothelial cells of larger blood vessels, and ANGPT2 was localized to tunica media of larger blood vessels. TIE2 protein was also present in luteal cells. In experiment 1, ANGPT1 protein expression was greater in O than C during early- and mid-luteal phases, and was greatest during late-luteal phase, less at the mid- and least at the early-luteal phase; 2) TIE2 protein expression was greatest at the mid-, less at the early- and least at the late-luteal phase; 3) ANGPT1 and 2 mRNA expression was greater at the mid- and late- than the early-luteal phase, and TIE2 mRNA expression was greatest at the late-, less at the mid- and least at the early-luteal phase. The ANGPT1/2 ratio was less at the early- than mid- or late-luteal phases. In experiment 2, ANGPT1 protein expression was greater in O during the mid-luteal phase than in other groups, and was greater at the mid- than early-luteal phase. TIE2 protein expression was highest at the mid-, less at the early- and least during the late-luteal phase. ANGPT1 and 2, and TIE2 mRNA expression was higher at the mid- than the early-luteal phase. During mid-luteal phase, ANGPT1 mRNA expression was greater in C than O and U, ANGPT2 was greatest in C, less in O and least in U, and TIE2 mRNA expression was greater in C than O and U. The ANGPT1/2 ratio was higher in U than in any other group. Comparison of FSH vs. Sal treatment effects (experiment 2 vs. experiment 1) demonstrated that FSH affected ANGPT1 and/or -2, and TIE2 protein and mRNA expression depending on luteal phase and/or diet. Thus, expression of ANGPTs and TIE2 in the CL changes during the luteal lifespan, indicating their involvement in luteal vascular formation, stabilization and degradation. Moreover, this study has demonstrated that plane of nutrition and/or FSH treatment affect the ANGPT system, and may alter luteal vascularity and luteal function in sheep.

Follicle stimulating hormone receptor protein is expressed in ovine uterus during the estrous cycle and utero-placenta during early pregnancy: An immunohistochemical study.

Follicle stimulating hormone (FSH) is a well characterized gonadotropin that controls primarily development and functions of ovarian follicles in mammalian species. FSH binds to a specific G protein-coupled receptor (FSHR) belonging to the glycoprotein hormone receptor family that plays an essential role in reproduction. Although the primary location of FSHR is in the gonads (mainly in ovarian follicles), FSHR protein and/or mRNA have also been detected in extragonadal female reproductive tissues including embryo, placenta, endometrium, cervix, ovarian cancer tissues, and/or endometriotic lesions in several species. To determine the pattern of FSHR expression in the uterus and placenta, uterine tissues were collected at the early, mid- and/or late luteal phases of the estrous cycle from non-treated or FSH-treated ewes, and utero-placental tissues were collected during early pregnancy followed by immunohistochemistry and image generation. FSHR was immunolocalized to several uterine and utero-placental compartments including luminal epithelium, endometrial glands and surrounding stroma, myometrium, and endothelium and vascular smooth muscle cells in endometrium, myometrium and mesometrium. Intensity of staining and distribution of FSHR in selected compartments differed and seems to depend on the stage of the estrous cycle or pregnancy, and FSH-treatment. These novel data demonstrate differential expression of FSHR protein indicating that FSH plays a specific role in regulation of uterine and utero-placenta functions in sheep.

Placental development during early pregnancy in sheep: Progesterone and estrogen receptor protein expression.

The aim of this study was to evaluate the pattern of protein expression of the steroid receptor isoforms of nuclear progesterone receptors (PGR) A and B, and estrogen receptors (ESR1 and 2) in utero-placental compartments during early pregnancy. Utero-placental tissues were collected from days 14-30 (n = 4 ewes/day), and uterine tissues were collected from non-pregnant ewes on day 10 after estrus (n = 4). Cross sections of formalin-fixed and paraffin embedded tissues were immunofluorescently stained to detect PGRAB, PGRB, ESR1 and ESR2, followed by image generation of entire cross-sections of uterine and utero-placental tissues, confocal imaging of individual uterine and utero-placental compartments, and image and statistical analyses. PGRAB, PGRB, ESR1 and ESR2 were detected in several compartments of uterine and utero-placental tissues. Quantitative image analysis of staining intensity demonstrated that compared to non-pregnant controls 1) expression of PGRAB and PGRB was less in luminal epithelium and endometrial glands from day 14-16 till 30; 2) PGRAB expression tended to be greater in endometrial and myometrial blood vessels on days 28 and/or 30; 3) PGRB expression in myometrum was lower on days 16 and 28; 4) ESR1 in endometrial stroma was lower in all days of pregnancy; 5) ESR2 expression was similar in all compartments and not affected by pregnancy stage; and 6) in FM, expression of steroid receptors was similar. Thus, we have demonstrated spatial and temporal expression of nuclear PGR and ESR isoforms in utero-placental compartments during early pregnancy.