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F H Yu

Publications and source records attributed to F H Yu.

5 recordsLinked to original sources
PubMed1991

Effects of hydroxyflutamide on rats treated with a superovulatory dose of pregnant mare serum gonadotropin.

Immature female rats treated with superovulatory doses of pregnant mare serum gonadotropin (PMSG) were used to study the effects of the antiandrogen hydroxyflutamide on steroid production, particularly the biologically active androgens, in two experiments. In the first experiment, animals were given either 5 mg hydroxyflutamide or vehicle alone at 30 and 36 h following 40 IU PMSG. Compared with the vehicle group, hydroxyflutamide treatment significantly reduced the percentage of degenerate oocytes recovered from oviducts (p less than 0.05). Serum levels of testosterone and androstenedione, and their aromatized product 17 beta-estradiol, significantly decreased (p less than 0.05) in the hydroxyflutamide-treated group; however, nonaromatizable androgen, 5 alpha-dihydrotestosterone, was not affected. In the second experiment, ovaries obtained 48 h after stimulation with 4 or 40 IU PMSG were incubated with and without hydroxyflutamide (10(-5) M) and (or) testosterone (10(-7) M) to study [4-14C]pregnenolone metabolism to major steroids. In 40 IU stimulated ovaries, hydroxyflutamide significantly decreased the metabolism of pregnenolone to progesterone (p less than 0.01) and androstenedione (p less than 0.01), while the production of 17 beta-estradiol increased significantly (p less than 0.05); however, pregnenolone conversions to testosterone and 5 alpha-dihydrotestosterone were not affected. Testosterone completely reversed the hydroxyflutamide-induced alteration of pregnenolone metabolism. In contrast, there was no difference in the pregnenolone conversion patterns between untreated and hydroxyflutamide or hydroxyflutamide plus testosterone groups in 4 IU stimulated ovaries. Present results confirm our previous finding that hydroxyflutamide decreases the percentage of abnormal oocytes recovered from superovulating rats and indicates that this hydroxyflutamide effect may be partly mediated by altered ovarian steroidogenesis following inhibition of androgen binding in the ovary.

Androgens↗
PubMed1989

Effects of a superovulatory dose of pregnant mare serum gonadotropin on follicular steroid contents and oocyte maturation in rats.

Our previous study has shown that superovulatory treatment with pregnant mare serum gonadotropin (PMSG) in rats caused marked alterations in ovarian and serum steroid responses and coincidental increase in degenerate oocytes (Yun et al., 1987). This study examined the effects of superovulatory treatment (20 IU PMSG) on follicular steroid contents and oocyte maturation. Immature female rats aged 28-30 days were injected with 4 or 20 IU PMSG and sacrificed at 24, 48, 60, and 72 hr. Compared to control regimen, follicular content of progesterone (P) in superovulated rats significantly (P less than .05) increased at 48 hr. Androgen (A) content significantly (P less than .01) decreased below control level at 24 hr but significantly (P less than .05) increased above control level at 48 hr and 60 hr. There was no significant change in 17 beta-estradiol (E) content between the two groups. In control regimen, the ratio of A/E sharply decreased and the ratios of P/E and P/A increased steadily from 24 hr. However, superovulatory regimen showed a consistently steady state in the overall ratios of follicular steroids after 24 hr. Nuclear maturation of the majority of control oocytes recovered from oviducts at 72 hr was synchronized at metaphase II, whereas superovulated oocytes displayed different stages varying from prophase I to metaphase II at 24, 48, and 72 hr. The results provide direct evidence of atypical ovulations in superovulated oocytes with premature or asynchronous nuclear maturation and demonstrate a close relationship between meiotically aberrant oocytes and abnormal follicular steroidogenesis following superovulation with PMSG in rats.

Animals↗