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Histological analysis of arteriovenous anastomosis-like vessels established in the corpus luteum of cows during luteolysis.

ABSTRACT: The mechanisms regulating the function and regression of the corpus luteum (CL) have not yet been elucidated in detail. The regressed CL of cows was previously reported to be filled with unusual vessels like arteriovenous anastomosis (AVA); however how these vessels are being established during luteolysis remains unknown.The bovine CL at different luteal stages and regressing bovine CL induced by prostaglandin F2? (PGF) were histologically analyzed using light and electron microscopic levels. The changes in mRNA expression of genes encoding ?-smooth muscle actin (SMA; Acta2) and transforming growth factor ?1 (Tgfb1) in luteal tissues were analyzed by quantitative RT-PCR.AVA-like vessels appeared in the regressed CL with a diameter less than 1.5 cm in which no functional luteal cells and macrophages were observed. Epithelioid cells in the AVA-like vessel wall were immunoreactive for SMA, and the lumen of the vessels were narrow. Immunoreaction for SMA was found in the tunica media of typical arteries and arterioles, and pericytes around capillary vessel. Cells with elongated cytoplasmic processes -resident fibroblasts expressing vimentin- distributed in the CL parenchyma without any association with blood vessels are also immunoreactive for SMA, and accumulated around arteries and arterioles during the late-luteal stage. In the regressed CL, walls of arteries and arterioles consisted of more than two layers of epithelioid cells positive for both SMA and desmin, suggesting that they are myofibroblasts transformed from fibroblasts. The percentage of the area positive for SMA and the mRNA expression of Acta2 were significantly increased in the regressed CL; however, they did not alter when a luteolytic dose of PGF was injected in vivo and collected within 24 h after the injection. On the other hand, Tgfb1, a known regulator for myofibroblast transformation, was significantly increased in PGF-induced regressing CL as well as in the CL during the late-luteal stage.SMA-positive myofibroblasts accumulates around the arteries and arterioles to form AVA-like vessels during luteolysis in cows. PGF indirectly regulates myofibroblast transformation through enhancing the expression of TGF?1. These peculiar AVA-like vessels may be involved in the regulation of blood flow in the bovine CL during luteolysis.

SUBMITTER: Nio-Kobayashi J

PROVIDER: S-EPMC5070142 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Histological analysis of arteriovenous anastomosis-like vessels established in the corpus luteum of cows during luteolysis.

Nio-Kobayashi Junko J Miyazaki Kaya K Hashiba Kazuhisa K Okuda Kiyoshi K Iwanaga Toshihiko T

Journal of ovarian research 20161019 1

<h4>Background</h4>The mechanisms regulating the function and regression of the corpus luteum (CL) have not yet been elucidated in detail. The regressed CL of cows was previously reported to be filled with unusual vessels like arteriovenous anastomosis (AVA); however how these vessels are being established during luteolysis remains unknown.<h4>Methods</h4>The bovine CL at different luteal stages and regressing bovine CL induced by prostaglandin F<sub>2α</sub> (PGF) were histologically analyzed u ...[more]

PMID: 27756340

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Project description:Simple Summary The corpus luteum (CL) is responsible for progesterone (P4) secretion. In the absence of pregnancy, luteolysis occurs, which leads to a reduction in P4 production, followed by the structural regression of the CL. In cows, prostaglandin F2α (PGF2α) is the main luteolytic factor. It is also an endogenous ligand for peroxisome proliferator-activated receptors (PPARs), which are important factors regulating mammalian reproductive function. However, the mechanisms of action of PPAR isoforms, i.e., PPARα, PPARδ and PPARγ, in the luteolytic pathways in cattle are still not fully understood. The aim of this in vitro study was to determine the expression of PPAR isoforms in the bovine CL throughout the estrous cycle, and their involvement in PGF2α-induced processes related to luteolysis. The obtained results indicate that the expression of PPARs changes in the bovine CL throughout the estrous cycle; moreover, PGF2α affects its expression. This study provides evidence that PPARγ, among all examined PPAR isoforms, could be involved in the regulation of PGF2α-induced luteolysis in cattle, and PPARs may affect CL regression at multiple sites. These results help to widen the knowledge of the mechanisms of luteal regression in the bovine CL. Abstract The participation of peroxisome proliferator-activated receptors (PPARs) in ovarian function in cattle is still not fully understood. The aim of this in vitro study was to determine: (i) the immunolocalization, mRNA expression and tissue concentration of PPARα, PPARδ and PPARγ in the bovine corpus luteum (CL) (n = 40) throughout the estrous cycle, and (ii) the involvement of PPAR in PGF2α-induced processes related to luteolysis. CL (n = 9) explants were cultured in the presence of PPAR antagonists (10−5 M) in combination with or without PGF2α receptor antagonist (10−5 M) and PGF2α (10−6 M). The mRNA and protein expression of PPARs was evaluated through qPCR, IHC, and ELISA, respectively. The results showed that PPAR mRNA and protein expression differed according to the luteal stages. PGF2α upregulated PPARδ and PPARγ mRNA expression in the bovine CL in vitro, whereas PPARγ increased the inhibitory effect of PGF2α by decreasing progesterone secretion and the mRNA expression of hydroxy-delta-5-steroid dehydrogenase, 3 β- and steroid delta-isomerase 1 (HSD3B1) in the CL explants; mRNA transcription of tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) was increased. The obtained results indicate that the mRNA and protein expression of PPARs changes in the bovine CL throughout the estrous cycle and under the influence of PGF2α. We suggest that isoform γ, among all examined PPARs, could be a factor involved in the regulation of PGF2α-induced processes related to luteolysis in the bovine CL. Further studies are needed to understand the role of PPAR in luteal regression in the CL of cattle.

Project description:In monoovulatory species like bovines, a striking diversity in regulation of the corpus luteum (CL) function exists within species during different stages of the luteal phase. The function and life span of CL appears to be regulated by the interplay of both luteotrophic and luteolytic factors, whose roles and actions are varied from one species to another. Although, studies continue to expand our current understanding of the cellular and molecular actions of prostaglandin F 2alpha (PGF2M-NM-1 - a physiological luteolysin)-induced luteolysis, knowledge of the mechanism whereby, PGF2M-NM-1 mediates its luteolytic actions remains poorly understood. The mechanism of PGF2M-NM-1-induced luteolysis is a complex process involving changes in expression of multiple genes encoding gene products that regulate steroidogenesis, stress related or apoptotic genes, factors involved in immune response and enzymes that stimulate PGF2M-NM-1 production. Thus, in the present study, efforts were made to identify the temporal changes in the global gene expression profile in the CL of buffalo cows in response to PGF2M-NM-1 treatment. The molecular signature of genome-wide transcriptional changes in the CL tissue subjected to PGF2M-NM-1-induced luteolysis will expand our knowledge on basic mechanism/s that regulates the luteolytic process. The results obtained in this study provide insight into the mechanisms underlying the PGF2M-NM-1- induced regression of CL.Keywords: CL, PGF2M-NM-1, gene expression The objective of this study was to identify the PGF2M-NM-1-induced temporal changes in transcriptome of bovine CL on day 11 of estrous cycle. In the experiments with buffalo cows, animals with history of normal estrous cyclicity were treated with Cloprostenol (an PGF2M-NM-1 analogue; 500 M-BM-5g i.m.) on day 11 of the estrous cycle to induce luteolysis and CL tissues were collected at (control; n=4 amimals/time point), 3 (n=2 animals/time point), 6 and 18 (n=3 animals/time point) h post PGF2M-NM-1 administration to examine gene expression changes associated with immediate early and delayed changes in the CL, respectively. Following retrieval of CL from the ovary, flash frozen in liquid nitrogen and stored at -70 M-BM-0C for the purpose of RNA isolation. The isolated RNA was labeled and hybridized to Affymetrix GeneChip Bovine Genome Arrays as per the manufacturerM-bM-^@M-^Ys instructions.

Dataset Information

Histological analysis of arteriovenous anastomosis-like vessels established in the corpus luteum of cows during luteolysis.

Publications

Histological analysis of arteriovenous anastomosis-like vessels established in the corpus luteum of cows during luteolysis.

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