Persistence of sleep-associated decrease in GnRH pulse frequency in the absence of gonadal steroids.

CONTEXT: There is dramatic slowing of GnRH pulse frequency during sleep in the early follicular phase of the menstrual cycle, but it is unknown whether this represents a primary effect of sleep or is dependent upon the sex steroid environment. OBJECTIVES: Our objective was to determine 1) whether sleep affects GnRH pulse frequency in postmenopausal women (PMW) in whom gonadal hormones are low and 2) whether this relationship changes with aging. DESIGN AND SETTING: Studies were performed in the Clinical Research Center of an academic medical center. SUBJECTS: Subjects included healthy PMW, 45-55 (n = 8) and 70-80 (n = 6) years old. INTERVENTIONS: Subjects were studied during one night of polysomnographic-recorded sleep and one night of monitored wake during which blood was sampled every 5 min for 8 h. MAIN OUTCOME MEASURES: Pulsatile secretion of free α-subunit (FAS), a marker of GnRH secretion, was assessed. RESULTS: There were no differences in sleep macroarchitecture or sleep efficiency [75 ± 12% (mean ± sd)] between older and younger PMW. The FAS interpulse interval was longer during sleep than nighttime wake in all women (60.5 ± 4.3 vs. 52.0 ± 2.8 min, P = 0.03) with a similar effect in the two groups. FAS pulse amplitude did not differ between sleep and wake periods (474.8 ± 36.7 vs. 478.2 ± 36.5 ng/liter, P = 0.9). CONCLUSIONS: Sleep is associated with a significant decline in GnRH pulse frequency in both older and younger PMW. Its persistence in PMW reinforces the important connection between sleep and GnRH secretion.

Impaired fibroblast growth factor receptor 1 signaling as a cause of normosmic idiopathic hypogonadotropic hypogonadism.

CONTEXT: FGFR1 mutations have been identified in about 10% of patients with Kallmann syndrome. Recently cases of idiopathic hypogonadotropic hypogonadism (IHH) with a normal sense of smell (nIHH) have been reported. AIMS: The objective of the study was to define the frequency of FGFR1 mutations in a large cohort of nIHH, delineate the spectrum of reproductive phenotypes, assess functionality of the FGFR1 mutant alleles in vitro, and investigate genotype-phenotype relationships. DESIGN: FGFR1 sequencing of 134 well-characterized nIHH patients (112 men and 22 women) and 270 healthy controls was performed. The impact of the identified mutations on FGFR1 function was assessed using structural prediction and in vitro studies. RESULTS: Nine nIHH subjects (five males and four females; 7%) harbor a heterozygous mutation in FGFR1 and exhibit a wide spectrum of pubertal development, ranging from absent puberty to reversal of IHH in both sexes. All mutations impair receptor function. The Y99C, Y228D, and I239T mutants impair the tertiary folding, resulting in incomplete glycosylation and reduced cell surface expression. The R250Q mutant reduces receptor affinity for FGF. The K618N, A671P, and Q680X mutants impair tyrosine kinase activity. However, the degree of functional impairment of the mutant receptors did not always correlate with the reproductive phenotype, and variable expressivity of the disease was noted within family members carrying the same FGFR1 mutation. These discrepancies were partially explained by additional mutations in known IHH loci. CONCLUSIONS: Loss-of-function mutations in FGFR1 underlie 7% of nIHH with different degrees of impairment in vitro. These mutations act in concert with other gene defects in several cases, consistent with oligogenicity.

GNRH1 mutations in patients with idiopathic hypogonadotropic hypogonadism.

Idiopathic hypogonadotropic hypogonadism (IHH) is a condition characterized by failure to undergo puberty in the setting of low sex steroids and low gonadotropins. IHH is due to abnormal secretion or action of the master reproductive hormone gonadotropin-releasing hormone (GnRH). Several genes have been found to be mutated in patients with IHH, yet to date no mutations have been identified in the most obvious candidate gene, GNRH1 itself, which encodes the preprohormone that is ultimately processed to produce GnRH. We screened DNA from 310 patients with normosmic IHH (nIHH) and 192 healthy control subjects for sequence changes in GNRH1. In 1 patient with severe congenital nIHH (with micropenis, bilateral cryptorchidism, and absent puberty), a homozygous frameshift mutation that is predicted to disrupt the 3 C-terminal amino acids of the GnRH decapeptide and to produce a premature stop codon was identified. Heterozygous variants not seen in controls were identified in 4 patients with nIHH: 1 nonsynonymous missense mutation in the eighth amino acid of the GnRH decapeptide, 1 nonsense mutation that causes premature termination within the GnRH-associated peptide (GAP), which lies C-terminal to the GnRH decapeptide within the GnRH precursor, and 2 sequence variants that cause nonsynonymous amino-acid substitutions in the signal peptide and in GnRH-associated peptide. Our results establish mutations in GNRH1 as a genetic cause of nIHH.

Comparison of clomiphene citrate, metformin, or the combination of both for first-line ovulation induction and achievement of pregnancy in 154 women with polycystic ovary syndrome.

OBJECTIVE: To determine which first-line medication is more effective in polycystic ovary syndrome (PCOS) patients for ovulation induction and pregnancy achievement and to verify whether any patient characteristic is associated with a better response to therapy. DESIGN: Observational comparative study. SETTING: Fertility clinic. PATIENT(S): One hundred fifty-four infertile women with oligomenorrhea and hyperandrogenism. INTERVENTION(S): Group 1 (56 patients) received clomiphene citrate (CC) 50 mg from days 5-9 of the cycle. Group 2 (57 patients) received 500 mg of metformin 3 times a day. Group 3 (41 patients) received both medications. MAIN OUTCOME MEASURE(S): Ovulation and pregnancy. RESULT(S): Patients receiving metformin alone had an increased ovulation rate compared with those receiving CC alone (75.4% vs. 50%). Patients on metformin had similar ovulation rates compared with those in the combination group (75.4% vs. 63.4%). Pregnancy rates were equivalent in the 3 groups. Response to metformin was independent of body weight and dose. Finally, nonsmoking predicted better ovulatory response overall as well as lower fasting glucose for CC and lower androgens for metformin. CONCLUSION(S): Metformin is better for ovulation induction than CC alone and equivalent for pregnancy achievement. We suggest that metformin can be used first for ovulation induction in patients with PCOS regardless of their weight and insulin levels because of its efficacy and known safety profile.

Absence of apparent circadian rhythms of gonadotropins and free alpha-subunit in postmenopausal women: evidence for distinct regulation relative to other hormonal rhythms.

Aging is associated with a decrease in gonadotropin levels in postmenopausal women (PMW) and is also associated with alterations in a number of circadian rhythms. The goals of this study were to determine the presence of circadian rhythms of gonadotropins and glycoprotein free alpha-subunit (FAS) in young and old PMW. Healthy, euthyroid PMW, ages 45 to 55 years (n = 11) and 70 to 80 years (n = 11), were admitted in the morning to start a 24-h constant routine of light, temperature, position, and activity. Subjects remained awake and semirecumbent for the duration of the study and were fed hourly snacks, and activity was monitored continuously. Blood was sampled every 5 min for two 8-h periods corresponding to the estimated acrophase and nadir of the temperature rhythm. Luteinizing hormone (LH) and FAS were measured in all samples and follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and cortisol in 20-min serum pools. Mean LH (p < 0.001), FSH (p < 0.002), and FAS (p < 0.002) were lower in older compared with younger PMW. Day/night differences in cortisol and TSH (p < 0.001) were present in all subjects. However, there were no day/night differences in LH in younger or older PMW or in FSH in younger or older PMW. There were no day/night differences in mean FAS in younger or older PMW or in FAS pulse frequency or amplitude. Thus, in controlled studies in which differences in cortisol and TSH were demonstrated, there were no day/night differences in LH, FSH, or FAS in PMW. These studies suggest that despite evidence of intact circadian rhythms of cortisol and TSH, gonadotropin secretion does not appear to follow a circadian pattern in PMW. Thus, the age-related decline in gonadotropin secretion in PMW is not associated with a dampening of circadian rhythmicity. The absence of day/night differences in FAS suggests that GnRH plays a more prominent role in FAS regulation than does thyrotropin-releasing hormone in PMW.

Negative feedback effects of gonadal steroids are preserved with aging in postmenopausal women.

There is now evidence for alterations in the neuroendocrine control of the reproductive axis with aging, but its sensitivity to gonadal steroid negative feedback remains controversial. To examine the independent effect of age and gonadal steroid negative feedback, younger (45-55 yr; n = 7) and older (70-80 yr; n = 6) postmenopausal women (PMW) were studied at baseline on no HRT, after 1 month of transdermal estrogen (50 microg/d; E) and again after a further month of E and 7 d of transvaginal progesterone (P) (100 mg bid; E + P). At each admission, blood was sampled every 5 min for 8 h for measurement of gonadotropin free alpha-subunit (FAS), which was used as a marker of GnRH pulse frequency. LH and FSH were measured in pooled samples. Midfollicular and midluteal phase levels of E2 and P were achieved during the E and E + P treatments and were not different between younger and older PMW. There was a negative feedback effect of E and E + P on mean LH (P < 0.0001) and an additional effect of age (P < 0.003), with older women having lower values throughout. Mean FSH was also decreased with E and E + P (P < 0.0001) and was consistently lower in the older women (P < 0.05). Mean FAS levels decreased with hormonal treatment (P < 0.0001) and age (P < 0.001), but the effect of hormonal treatment was attenuated in the older group (P < 0.005). FAS pulse frequency was unchanged with addition of E, but dramatically decreased with E + P (P < 0.002). Both hormonal replacement (P < 0.05) and age (P < 0.005) decreased FAS pulse amplitude, an effect that was attributable entirely to E as there was no additional change with E + P. These studies indicate that: 1) both age and gonadal steroids independently decrease mean LH, FSH, and FAS in PMW; 2) responsiveness to steroid negative feedback on FAS is attenuated with aging in absolute but not relative terms, whereas the effect on mean levels of LH and FSH is clearly preserved; and 3) FAS pulse frequency is unchanged with E2 administration but decreases dramatically with addition of P in both old and young PMW.