|Budget Amount *help
¥3,900,000 (Direct Cost : ¥3,900,000)
Fiscal Year 1994 : ¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1993 : ¥1,900,000 (Direct Cost : ¥1,900,000)
The present study was undertaken to investigate the roles of GH and renin-angiotensisn system (RAS) on follicular growth, oocyte maturation, and ovulation in the in vitro perfused rabbit ovaries. Ovulation did not occur in any ovaries perfused with GH at a concentration of 1,10,100, or 200 ng/ml, but the addition of GH to the perfusate increased the folicle diameter in a dose-dependent manner. The percent increase in follicle diameter in ovaries treated with GH was significantly correlated with the intraovarian IGF-I content. Exposure to GH significantly stimulated the resumption of meiosis in the follicular oocytes compared with that in ovaries perfused with medium alone. Furthemore, GH significantly stimulated the resumption of meiosis in ovulated ova and follicular oocytes in ovaries treated with 5 IU hCG.Thus, exposure to GH stimulated follicular growth, oocyte maturation, and production of IGF-I in the in vitro perfused rabbit ovaries, which indicates that the ovary is in fact a site of GH reception and action. The second experiment was undertaken to investigate the role of exogenous and endogenous angiotensin II (Ang II) in ovarian steroidogenesis and production of prostaglandin (PG) in in vitro perfused rabbit ovaries. The addition of 100 or 10 mug Ang II at 2-h interbals to the perfusate significantly stimulated estradiol (E_2) production by perfused rabbit ovaries. Ang II also significantly stimulated both PGE_2 and PGF_<2alpha> production, while the addition of saralasin to the perfusate significantly inhibited the Ang II-stimulated production of PG.The ovulatory efficiency in ovaries treated with hCG alone or hCG plus saralasin was significantly correlated with PG production by perfused rabbit ovaries at 12 h after exposure to hCG.
In conclusion, these results indicate that GH-I GF-I system and RAS in the ovary enhanced the effects of gonadotropins, acting synergistically to promote the ovulatory process.