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| Registros recuperados: 77 | |
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| OHTANI, Masayuki; OKI, Naoko; TANIMURA, Miyune; KOBAYASHI, Shu-ichi; ACOSTA, Tomas J.; HAYASHI, Kanako; MIYAMOTO, Akio; 宮本, 明夫. |
| It is well known that an injection of prostaglandin F2α (PGF2α) or its analogue during the mid luteal phase of the estrous cycle induces a rapid decrease in plasma progesterone (P4) concentration, followed by luteolysis in the cow. There is evidence that a potent vasoactive peptide, endothelin-1 (ET-1), is produced in the bovine corpus luteum (CL), and that it is directly involved in luteolysis. We previously found that ET-1 concentrations in the peripheral plasma increase during the period of luteolysis and ovulation in cows. However, it is not clear whether the elevation of peripheral plasma ET-1 concentration observed during luteolysis and ovulation originates exclusively from the ovary and/or CL. Such a profile of plasma ET-1 concentration may be... |
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Palavras-chave: Endothelin; Progesterone; Plasma; Calves; Cows. |
| Ano: 2001 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2973 |
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| HAYASHI, Ken-Go; MATSUI, Motozumi; ACOSTA, Tomas J.; KIDA, Katsuya; MIYAMOTO, Akio; 松井, 基純; 木田, 克弥; 宮本, 明夫. |
| Luteinizing hormone (LH) surge and follicle rupture act as trigger to start corpus luteum (CL) formation. Thus, we aimed to investigate whether a dominant follicle that has not been exposed to an LH surge can become a functional CL. For this purpose, follicular fluid from the dominant follicles (DF) of cows was aspirated before or after a GnRH-induced LH surge, and subsequent CL formation was observed. Holstein cows were divided into four groups as follows: Luteal phase, a DF was aspirated 7 days after GnRH injection; Pre-LH surge, a DF was aspirated 42 h after PGF2α injection during the mid luteal phase; Post-LH surge, a DF was aspirated 24 h after GnRH injection following PGF2α; and Intact follicle, ovulation was induced by GnRH injection after PGF2α.... |
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Palavras-chave: Corpus luteum formation; Cow; Follicle aspiration; LH surge. |
| Ano: 2006 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2982 |
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| SHIRASUNA, Koumei; WATANABE, Sho; NAGAI, Kaya; SASAHARA, Kiemi; SHIMIZU, Takashi; RICKEN, Albert M.; SPANEL-BOROWSKI, Katharina; MIYAMOTO, Akio; 白砂, 孔明; 清水, 隆; 宮本, 明夫. |
| Cell-to-cell interaction via cell contact-dependent pathway is essentially important for maintenance and regulation of corpus luteum (CL) integrity and its physiological actions. The objective of the present study was to evaluate the mRNA expression of the cell adhesion molecules (CAMs) that are constituent factors of gap junctions [connexin (Cx) 43] and adherence junctions (VE-, E-, N-cadherin) in two types of endothelial cells from the mid CL and in CL tissue during the estrous cycle and PGF2α-induced luteolysis in the cow. Specific mRNA expression for Cx43 and N-cadherin was detected in cytokeratin-positive (CK+) and cytokeratin-negative (CK-) luteal endothelial cells (EC) and fully luteinized granulosa cells (LGC). E-cadherin mRNA was expressed in... |
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Palavras-chave: Cadherin; Connexin; Corpus luteum; Cow; Luteolysis. |
| Ano: 2007 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2988 |
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| SHIRASUNA, Koumei; ASAHI, Takayuki; SASAKI, Motoki; SHIMIZU, Takashi; MIYAMOTO, Akio; 白砂, 孔明; 佐々木, 基樹; 清水, 隆; 宮本, 明夫. |
| We have shown that luteal blood flow increases in the peripheral vasculature of the mature corpus luteum (CL) prior to the onset of luteolysis in response to prostaglandin F2α (PGF2α) in the cow, but this phenomenon does not occur in the early CL. We therefore hypothesize that this acute increase of luteal blood flow occurs by vasodilation of large blood vessels due to local release of nitric oxide (NO). In the present study, we characterized the CL vasculature together with endothelial NO synthase (eNOS) expression during the estrous cycle in the cow. Immunohistochemistry was used to quantify the number of arteriolovenous vessels (surrounded with smooth muscle actin-positive smooth muscle cells), capillaries (with von Willebrand Factor-positive... |
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Palavras-chave: Blood vessels; Corpus luteum; ENOS; Luteolysis. |
| Ano: 2010 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2989 |
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| ACOSTA, Tomas J.; HAYASHI, Ken-Go; MATSUI, Motozumi; MIYAMOTO, Akio; 松井, 基純; 宮本, 明夫. |
| Increase in the blood supply to individual follicles appears to be associated with follicular growth rates and the ability to become the dominant follicle, while reduced thecal vascularity appears to be closely associated with follicular atresia. Therefore, this study aimed to determine the real-time changes in the vascularity of the follicle wall during the first follicular wave in cycling Holstein cows. Normally cycling and lactating cows (n=5) were examined by transrectal color Doppler ultrasonography (the sensitivity for velocity: > 2 mm/sec) to determine the changes in the vasculature of the follicle wall (presence or absence of blood flow) and the diameter of follicles. A new follicular wave and ovulation were induced by GnRH injection at 48 h... |
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Palavras-chave: Blood flow; Follicular wave; Selection; Deviation; Cow. |
| Ano: 2005 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2979 |
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| MAGATA, Fumie; SHIRASUNA, Koumei; STRÜVE, Klaas; HERZOG, Kathrin; SHIMIZU, Takashi; BOLLWEIN, Heinrich; MIYAMOTO, Akio; 清水, 隆; 宮本, 明夫. |
| Persistence of the corpus luteum (CL) in cattle usually occurs during the puerperium and is associated with interference of prostaglandin (PG) F2α release from the uterus. The objective of the present study was to determine for the first time the gene expressions in the persistent CL compared with the CL of pregnancy and cyclic CL. Three types of CL biopsy samples were collected from 32 lactating Holstein cows: (1) CL persisting for 29 to 33 days after the first ovulation postpartum (persistent CL, n=9), (2) CL between days 29 and 33 of early pregnancy (CL of pregnancy, n=8) and (3) CL between days 10 and 13 of the estrous cycle (cyclic CL, n=27). mRNA expression of 2',5'-oligoadenylate synthetase-1 was upregulated only in the CL of pregnancy, confirming... |
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Palavras-chave: Dairy cow; Early pregnancy; Persistent corpus luteum; MRNA expression. |
| Ano: 2012 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4039 |
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| Shirasuna, Koumei; Watanabe, S.; Oki, N.; Wijayagunawardane, M. P. B.; Matsui, Motozumi; Ohtani, M.; Miyamoto, Akio; 白砂, 孔明; 松井, 基純; 宮本, 明夫. |
| Prostaglandin F-2 alpha (PGF(2 alpha)) is the primary luteolysin in the cow, and luteal endothelin-1 (ET-1) interacts with PGF(2 alpha) during the process of luteolysis. In contrast, a developing corpus luteum (CL) is refractory to exogenous administration of PGF(2 alpha). Thus, the present study was aimed to investigate the functional relationship between ET-1 and PGF(2 alpha) in the mid-CL (PGF(2 alpha)-sensitive) and early-CL (PGF(2 alpha)-refractory). In the mid-CL model, cows (n = 6/treatment) were assigned to receive one of five types of treatments on day 10 of the estrous cycle: (1) an injection of saline; control, (2) a 500 jig of PGF2. analogue (sufficient dose to induce luteolytis); full-PG, (3) an intraluteal injection of 0.25 mg ET-1; ET-1, (4)... |
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Palavras-chave: Endothelin-1; Prostaglandin F-2 alpha; Luteolysis; Corpus luteum; Cow. |
| Ano: 2006 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/825 |
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| KAWASHIMA, Chiho; MATSUI, Motozumi; SHIMIZU, Takashi; KIDA, Katsuya; MIYAMOTO, Akio; 川島, 千帆; 松井, 基純; 清水, 隆; 木田, 克弥; 宮本, 明夫. |
| During recent decades, milk production per cow has increased drastically due to improved management, nutrition, and genetic selection; however, the reproductive performance of high-producing dairy cows has been declining. One of the factors responsible for this low reproductive performance is negative energy balance (NEB). NEB affects the onset of first ovulation in early postpartum cows. It is generally accepted that early first ovulation positively relates to the resumption of normal ovarian function, first service, and conception rate in dairy cows. Hence, delayed first ovulation has a negative impact on subsequent fertility. The metabolic condition of cows in NEB shifts to catabolic metabolism, which in turn causes increased plasma growth hormone and... |
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Palavras-chave: Β-Carotene; Dairy cow; First follicular wave postpartum; First ovulation; Metabolic hormone. |
| Ano: 2012 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4041 |
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| KOBAYASHI, Shu-ichi; MIYAMOTO, Akio; 宮本, 明夫. |
| Luteal cells utilize lipoproteins (LIPs) for progesterone (P) synthesis. A luteolysin prostaglandin F2α (PGF 2α) has shown to prevent the LIPs utilization for steroidogenesis in bovine midcycle luteal cells. However, a luteolytic injection of PGF2α before Day 5 (Day 0=estrus) can not induce the regression of the corpus luteum (CL). This suggests that the intraluteal mechanism of PGF2 α action on the LIPs utilization in early CL is different from that of the mid luteal stage. Thus, this study aimed to investigate the interaction between PGF2 α and LIPs on the secretion of P and oxytocin (OT) from bovine early CL. An in vitro microdialysis system (MDS) was used as a model. Each bovine early CL (Days 3-4) was implanted with the MDS, and maintained in an organ... |
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Palavras-chave: PGF2α; Lipoproteins; Early CL; Cow. |
| Ano: 2000 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2972 |
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| Registros recuperados: 77 | |
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