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(72) CHANGES OF mRNA EXPRESSION OF ANGIOGENIC FACTORS AND RELATED RECEPTORS DURING FOLLICULAR DEVELOPMENT IN GILTS. Shimizu, Takashi1, Jiang, Jin-Yi1, Sasada, Hiroshi1, Sato, Eimei1, 1 Laboratory of Animal Reproduction, Sendai, JP ABSTRACT- The interaction between angiogenic factors and related receptors is closely associated with follicular angiogenesis. We investigated whether changes occurred in capillary network, and mRNA expression of angiogenic factors and related receptors in porcine follicles at different developmental stages. Ovaries in gilts were collected 72 h after equine chorionic gonadotropin (eCG, 1250 IU) treatment for histological observation. On the basis of their diameter, follicles were separated into five classes: 0.5-0.9 mm; 1.0-2.9 mm; 3.0-4.9 mm; 5.0-6.0 mm; >6.0 mm. Granulosa cells and theca tissues in individual of small (<4 mm), medium (4-5 mm) or large (>5 mm) follicles were collected for detection of mRNA expression of vascular endothelial growth factor (VEGF) 120, VEGF164, basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) in granulosa cells, and fms-like tyrosine kinase (Flt-1), fetal liver kinase (Flk-1), bFGF receptor (bFGF-R) and EGF receptor (EGF-R) in thecal tissue by RT-PCR. eCG treatment resulted in the emergence of healthy preovulatory follicles (>6.0 mm in diameter) that possessed more capillaries in the theca interna. The number of capillaries in theca interna increased significantly in healthy follicles larger than 3 mm in diameter in eCG group compared with those controls. On the other hand, the number of capillaries in atretic follicles was not changed in both groups. Expression of VEGF120, VEGF164 and bFGF mRNAs was significantly higher in granulosa cells of medium and large follicles from ovaries of prepubertal gilts with eCG treatment. Expression of Flt-1, Flk-1/KDR and bFGF-R mRNAs was significantly higher in thecal cells of medium and large follicles with eCG treatment. Expression of EGF mRNA was significantly greater in granulosa cells of small, medium and large follicles from ovaries with eCG treatment, but EGF-R mRNA expression in thecal tissue did not change. These data indicate that preovulatory follicles possessed more capillary network and expressed more mRNAs of angiogenic factors in granulosa cells and related receptors in thecal tissue. We concluded that VEGF120, VEGF164 and bFGF are greatly involved in the process of follicular development in prepubertal gilts with eCG treatment. KEY WORDS: Angiogenesis, Follicular Development, Pig |
