Objective: To evaluate whether a combination of letrozole and clomiphene citrate (CC) results in higher ovulation rates than letrozole alone in infertile women with polycystic ovary syndrome (PCOS). Design: Open-label randomized controlled trial. Setting: Academic medical center using two clinic sites. Patient(s): Women 18-40 years of age with a diagnosis of infertility and PCOS as defined by the Rotterdam criteria and no other known cause of infertility. Interventions(s): Participants were randomized in a 1:1 ratio, stratified by age and body mass index, to either 2.5 mg letrozole alone or the combination of 2.5 mg letrozole and 50 mg CC daily on cycle days 3-7 for one treatment cycle. Main Outcome Measure(s): Ovulation defined as mid-luteal serum progesterone concentration R3 ng/mL. Result(s): Seventy patients were randomized: 35 to letrozole alone and 35 to letrozole and CC. Results were analyzed according to the intention-to-treat principle. Women who received the combination of letrozole and CC had a statistically higher ovulation rate compared with those who received letrozole alone (27 of 35 women [77%] vs. 15 of 35 women [43%]). There were no serious adverse events or multiple-gestation pregnancies in either group. The side-effects profile was similar in the two treatment groups. Conclusion(s): The combination of letrozole and CC was associated with a higher ovulation rate compared with letrozole alone in women with infertility and PCOS. Further studies are needed to evaluate the effect on live birth rate.
Drs Jacobs and Mejia had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Mice with a deletion of Gα(q/11) in granulosa cells were previously shown to be subfertile. They also have a reduced ovulatory response due to a deficiency in the ability of the activated LH receptor to fully induce the granulosa cell progesterone receptor. Because this conditional deletion of Gα(q/11) will interfere with the actions of any G protein-coupled receptor that activates G(q/11) in granulosa or luteal cells, we sought to determine whether the actions of other hormones that contribute to fertility were also impaired. We focused our attention on prostaglandin F2 (PGF2)α, because this hormone is known to activate phospholipase C (a prominent Gα(q/11) effector) in luteal cells and because the action of PGF2α on luteal cells is the first step in the murine parturition pathway. Our data show that the conditional deletion of Gα(q/11) from granulosa cells prevents the ability of PGF2α to induce Akr1c18 in luteal cells. Akr1c18 codes for 20α-hydroxysteroid dehydrogenase, an enzyme that inactivates progesterone. The PGF2α-mediated induction of this enzyme towards the end of pregnancy increases the inactivation of progesterone and precipitates parturition in mice. Thus, the conditional deletion of Gαq/11 from granulosa/luteal cells prevents the progesterone withdrawal that occurs at the end of pregnancy and impairs parturition. This novel molecular defect contributes to the subfertile phenotype of the mice with a deletion of Gα(q/11) from granulosa cells.
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