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Expression of Angiopoietin (ANPT)‐1, ANPT‐2 and their Receptors in Dominant Follicles during Periovulatory Period in GnRH‐Treated Cow
Author(s) -
Shimizu T,
Berisha B,
Schams D,
Miyamoto A
Publication year - 2007
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/j.1439-0531.2006.00748.x
Subject(s) - ovulation , corpus luteum , medicine , endocrinology , follicular phase , luteinizing hormone , follicle , biology , gonadotropin releasing hormone , ovarian follicle , ovary , receptor , gonadotropin , angiopoietin , andrology , hormone , vascular endothelial growth factor , vegf receptors
Contents Ovarian follicular vasculature is involved in follicular development and ovulation. Angiopoietin (ANPT)‐Tie system is important for vascularization of the tissue surrounding the developing follicles and corpus luteum (CL). To determine how the expression of ANPT‐1, ANPT‐2 and their receptors in the follicles would be associated with the ovulatory process, the present study was conducted to examine mRNA expressions of ANPT‐1, ANPT‐2 and their receptors during the periovulatory phase in gonadotrophin‐releasing hormone (GnRH)‐treated cows. The ovaries were collected by transvaginal ovariectomy (n = 5, cows/group) and the follicles (n = 5, one follicle/cow) were classified into following groups: before GnRH administration [before luteinizing hormone (LH) surge]; 3–5 h after GnRH (during LH surge); 10 h after GnRH; 20 h after GnRH; 25 h after GnRH (peri‐ovulation); and early CL (days 2–3). The mRNA expression was analysed by quantitative real‐time PCR (rotor‐gene 3000). Angiopoietin‐1 expression rapidly decreased at 3–5 h and kept low level at 10 h after GnRH treatment compared with that before GnRH, and returned to the level before LH surge in the follicles >20 h after GnRH treatment. The levels of ANPT‐2 mRNA decreased at 10 and 25 h after treatment compared with other periods. The ratio of ANPT‐2/ANPT‐1 (an index for destabilization of blood vessels) increased in the follicles at 3–5 h after GnRH treatment only. Both of Tie‐1 and Tie‐2 receptor expressions decreased in the follicles at 25 h after GnRH treatment. The results of the present study indicated that mRNA expressions of ANPT‐1, ANPT‐2 and their receptors changed in the bovine follicles during periovulatory period. These results suggest that angiopoietin‐Tie system is associated with the initiation of vasculature of follicle that grows towards ovulation.