Eicosanoids and ovulation.

PGs and probably other eicosanoids play a fundamental role in the process of ovulation, more specifically in the mechanism of follicle wall rupture. Although the nature of this role has yet to be established a number of plausible theories exist. It seems likely that altered PG metabolism is responsible for some cases of human female subfertility. The potential for fertility control by PG inhibition is an exciting possibility for the future.

The effect of prostaglandin synthetase inhibitors on human preovulatory follicular fluid prostaglandin, thromboxane, and leukotriene concentrations.

This study evaluates the eicosanoid concentration in luteinized unruptured follicles (LUFs) on the ovaries of patients who had been treated with inhibitors of prostaglandin synthetase. Indomethacin, bromfenac, or azapropazone (or a placebo) was administered orally to 41 women during the periovulatory period. Follicular development was monitored by serial ultrasound examinations, and the onset of ovulation was regulated by an injection of hCG. Follicular fluid was aspirated during sterilization by minilaparotomy, which was performed just before the expected time of ovulation. Prostaglandin E2 and PGF2 alpha levels in the fluid were significantly reduced by indomethacin and bromfenac compared to those after placebo treatment. Bromfenac also reduced the follicular fluid leukotriene B4 level. Therefore, the development of luteinized unruptured follicles after treatment with nonsteroidal antiinflammatory drugs appears to be associated with a significant decrease in the synthesis of ovarian eicosanoids.

Ovarian follicular fluid eicosanoid concentrations during the pre-ovulatory period in humans.

Prostaglandins are involved in ovulation and in every mammal studied so far, ovulation has been inhibited by prostaglandin inhibition. Information regarding the role of leukotrienes and thromboxanes in ovulation is more limited. In order to study the production of eicosanoids in human pre-ovulatory follicular fluid, follicular aspiration was timed by means of serial ultrasound scans and human chorionic gonadotrophin (hCG) to be immediately pre-ovulatory. 11 women were studied and the eicosanoids measured by radioimmunoassay (RIA). The follicular fluid was found to contain leukotrienes (LT) B4, LTC4 (D4, E4), prostaglandin (PG) E2, PGF2 alpha 6 keto PGF1 alpha k and thromboxane (TX) B2. This is the first published report of leukotrienes in human follicular fluid in spontaneous cycles, and is one of the few reports showing prostaglandins and thromboxanes. The significance of demonstrating leukotrienes in human follicular fluid is discussed as is the correlation between individual eicosanoids in the human ovary.

Pituitary-ovarian activity when switching from various monophasic pills to a triphasic pill.

This study was prompted by the various recommendations given by different oral contraceptive manufacturers to women who wish to switch from a monophasic to a triphasic formulation. Ten women who switched from a variety of monophasic pills to a levonorgestrel triphasic pill formulation after a 7-day pill-free interval were studied. Follicular maturation was monitored by ultrasound scan, and the levels of serum follicle stimulating hormone (FSH), luteinizing hormone (LH), progesterone (P) and estradiol (E2) measured. Pituitary-ovarian activity was suppressed in six of the ten women studied, while in the remaining four women there was some pituitary-ovarian activity during the first 10 days on the triphasic pill. These findings suggest a shorter pill-free interval, as advised in USA data sheets, may be less likely to result in pill failures when women switch from a monophasic to a triphasic preparation.