Multiplexed Serum Biomarkers to Discriminate Nonviable and Ectopic Pregnancy.

OBJECTIVE: The use of multiplexed biomarkers may improve the diagnosis of normal and abnormal early pregnancies. In this study we assessed 24 markers with multiple machine learning-based methodologies to evaluate combinations of top candidates to develop a multiplexed prediction model for identification of 1) viability and 2) location of an early pregnancy. DESIGN: A nested case-control design evaluating the predictive ability and discrimination of biomarkers in patients at risk of early pregnancy failure in the first trimester to classify viability and location SUBJECTS: 218 individuals with a symptomatic (pain and/or bleeding) early pregnancy: 75 with an ongoing intrauterine gestation, 68 ectopic pregnancies, and 75 miscarriages. INTERVENTIONS: Serum values of 24 biomarkers were assessed in the same patients. Multiple machine learning-based methodologies to evaluate combinations of these top candidates to develop a multiplexed prediction model for identification of 1) a nonviable pregnancy (ongoing intrauterine pregnancy vs miscarriage or ectopic pregnancy) and 2) an ectopic pregnancy (ectopic pregnancy vs ongoing intrauterine pregnancy or miscarriage). MAIN OUTCOME MEASURES: The predicted classification by each model was compared to actual diagnosis and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), conclusive classification, and accuracy were calculated. RESULTS: Models using classification regression tree analysis using three markers (PSG3, CG-Alpha and PAPPA) were able to predict a maximum sensitivity 93.3%, a maximum specificity 98.6%. The model with the highest accuracy was 97.4% (with 70.2% receiving classification). Models using an overlapping group of three markers (sFLT, PSG3 and TFP12) achieved a maximum sensitivity of 98.5%. and a maximum specificity of 95.3%. The model with the highest accuracy was 94.4% (with 65.6% receiving classification). When the models were used simultaneously the conclusive classification increased to 72.7% with an accuracy 95.9%. The predictive ability of the biomarkers random forest produced similar test characteristics when using 11 predictive markers. CONCLUSION: We have demonstrated a pool of biomarkers from divergent biological pathways that can be used to classify individuals with potential early pregnancy loss. The biomarkers CG-Alpha, PAPPA and PSG3 can be used to predict viability and sFLT, TPFI2 and PSG3 can be used to predict pregnancy location.

Evaluation of novel biomarkers for early pregnancy outcome prediction†.

OBJECTIVE: To assess performance and discriminatory capacity of commercially available enzyme-linked immunosorbent assays of biomarkers for predicting first trimester pregnancy outcome in a multi-center cohort. DESIGN: In a case-control study at three academic centers of women with pain and bleeding in early pregnancy, enzyme-linked immunosorbent assays of biomarkers were screened for assay performance. Performance was assessed via functional sensitivity, assay reportable range, recovery/linearity, and intra-assay precision (%Coefficient of Variation). Top candidates were analyzed for discriminatory capacity for viability and location among 210 women with tubal ectopic pregnancy, viable intrauterine pregnancy, or miscarriage. Assay discrimination was assessed by visual plots, area under the curve with 95% confidence intervals, and measures of central tendency with two-sample t-tests. RESULTS: Of 25 biomarkers evaluated, 22 demonstrated good or acceptable assay performance. Transgelin-2, oviductal glycoprotein, and integrin-linked kinase were rejected due to poor performance. The best biomarkers for discrimination of pregnancy location were pregnancy-specific beta-1-glycoprotein 9, pregnancy-specific beta-1-glycoprotein 1, insulin-like growth factor binding protein 1, kisspeptin (KISS1), pregnancy-specific beta-1-glycoprotein 3, and beta parvin (PARVB). The best biomarkers for discrimination of pregnancy viability were pregnancy-specific beta-1-glycoprotein 9, pregnancy-specific beta-1-glycoprotein 3, EH domain-containing protein 3, KISS1, WAP four-disulfide core domain protein 2 (HE4), quiescin sulfhydryl oxidase 2, and pregnancy-specific beta-1-glycoprotein 1. CONCLUSION: Performance of commercially available enzyme-linked immunosorbent assays was acceptable for a panel of novel biomarkers to predict early pregnancy outcome. Of these, six and seven candidates demonstrated good discriminatory capacity of pregnancy location and viability, respectively, when validated in a distinct external population. Four markers demonstrated good discrimination for both location and viability.

Validation of a multiple marker test for early pregnancy outcome prediction.

PURPOSE: To validate the use of a multiple biomarker test panel for predicting first trimester pregnancy outcome in a multi-center cohort. METHODS: A case-control study of women presenting with pain and bleeding in early pregnancy at 5-10 weeks gestational age was performed at three academic centers. Sera from women with ectopic pregnancy (EP), viable intrauterine pregnancy (IUP), and miscarriage (SAB) were analyzed via immunoassay for Activin A (AA), Progesterone (P4), A Disintegrin And Metalloprotease-12 (ADAM12), pregnancy-associated plasma protein A (PAPP-A), glycodelin (Glyc), and human chorionic gonadotropin (hCG). Biomarkers were assessed for reproducibility using medians, ranges, standard deviations, and area under receiver-operating characteristic curve (AUC) and accuracy in early pregnancy outcome classification compared to a previous derivation population. RESULTS: In 192 pregnancies, the biomarkers demonstrated good reproducibility with similar medians, ranges, and AUCs when compared to the derivation population except glycodelin. Pregnancy location was conclusively classified in 53% (n = 94) of the whole study sample with 78% accuracy. Pregnancy viability was conclusively classified in 58% (n = 112) of the new sample with 89% accuracy. Results were similar with subsequent model revisions where glycodelin was excluded and in the subgroups of subjects with a hCG below 2000 mIU/mL and a gestational age less than 6 weeks. CONCLUSION: The use of a panel of biomarkers to maximize test accuracy of a prediction of pregnancy location and prediction of pregnancy viability was reproducible and validated in an external population from which it was derived, but clinical utility is limited based on the test characteristics obtained.

Effects of preconception lifestyle intervention in infertile women with obesity: The FIT-PLESE randomized controlled trial.

BACKGROUND: Women with obesity and infertility are counseled to lose weight prior to conception and infertility treatment to improve pregnancy rates and birth outcomes, although confirmatory evidence from randomized trials is lacking. We assessed whether a preconception intensive lifestyle intervention with acute weight loss is superior to a weight neutral intervention at achieving a healthy live birth. METHODS AND FINDINGS: In this open-label, randomized controlled study (FIT-PLESE), 379 women with obesity (BMI ≥ 30 kg/m2) and unexplained infertility were randomly assigned in a 1:1 ratio to 2 preconception lifestyle modification groups lasting 16 weeks, between July 2015 and July 2018 (final follow-up September 2019) followed by infertility therapy. The primary outcome was the healthy live birth (term infant of normal weight without major anomalies) incidence. This was conducted at 9 academic health centers across the United States. The intensive group underwent increased physical activity and weight loss (target 7%) through meal replacements and medication (Orlistat) compared to a standard group with increased physical activity alone without weight loss. This was followed by standardized empiric infertility treatment consisting of 3 cycles of ovarian stimulation/intrauterine insemination. Outcomes of any resulting pregnancy were tracked. Among 191 women randomized to standard lifestyle group, 40 dropped out of the study before conception; among 188 women randomized to intensive lifestyle group, 31 dropped out of the study before conception. All the randomized women were included in the intent-to-treat analysis for primary outcome of a healthy live birth. There were no significant differences in the incidence of healthy live births [standard 29/191(15.2%), intensive 23/188(12.2%), rate ratio 0.81 (0.48 to 1.34), P = 0.40]. Intensive had significant weight loss compared to standard (-6.6 ± 5.4% versus -0.3 ± 3.2%, P < 0.001). There were improvements in metabolic health, including a marked decrease in incidence of the metabolic syndrome (baseline to 16 weeks: standard: 53.6% to 49.4%, intensive 52.8% to 32.2%, P = 0.003). Gastrointestinal side effects were significantly more common in intensive. There was a higher, but nonsignificant, first trimester pregnancy loss in the intensive group (33.3% versus 23.7% in standard, 95% rate ratio 1.40, 95% confidence interval [CI]: 0.79 to 2.50). The main limitations of the study are the limited power of the study to detect rare complications and the design difficulty in finding an adequate time matched control intervention, as the standard exercise intervention may have potentially been helpful or harmful. CONCLUSIONS: A preconception intensive lifestyle intervention for weight loss did not improve fertility or birth outcomes compared to an exercise intervention without targeted weight loss. Improvement in metabolic health may not translate into improved female fecundity. TRIAL REGISTRATION: ClinicalTrials.gov NCT02432209.

Estimating testosterone concentrations in adolescent girls: Comparison of two direct immunoassays to liquid chromatography-tandem mass spectrometry.

CONTEXT: The appropriate role of direct total testosterone (T) immunoassays in reproductive research is controversial. OBJECTIVE: To assess the concordance between two direct immunoassays and a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for total T in adolescent girls with measured concentrations < 50 ng/dl. DESIGN: Cross-sectional analysis. SETTING: Academic medical center. PARTICIPANTS: Adolescent girls (age 8.4-18.1 years) participating in clinical research protocols. INTERVENTION: Paired blood samples were obtained for total T by LC-MS/MS (n = 66; Mayo Clinic Laboratory) and by direct immunoassay (Center for Research in Reproduction)-either radioimmunoassay (RIA; n = 31) or chemiluminescence immunoassay (CLIA; n = 35). At the time of assay, laboratories were unaware that results would be compared. MAIN OUTCOME MEASURE: Measurement agreement between immunoassay and LC-MS/MS. RESULTS: Measured T concentrations (LC-MS/MS) were <7 to 44 ng/dl. The average difference between RIA and LC-MS/MS was 0.84 [-0.89, 2.56] ng/dl (mean [95% confidence interval]). RIA correlated very strongly with LC-MS/MS (r = 0.899; p < 0.0001); and both Deming regression and Bland-Altman analysis suggested no bias. The average difference between chemiluminescence and LC-MS/MS was 1.39 [-0.83, 3.60] ng/dl. CLIA correlated strongly with LC-MS/MS (r = 0.806; p < 0.0001). While Bland-Altman analysis suggested no systematic bias, Deming regression analysis suggested that, as measured values increased, values obtained by CLIA tended to be progressively, albeit only modestly, higher than those obtained by LC-MS/MS. CONCLUSIONS: These data support the use of rigorously-performed and carefully-validated direct T immunoassays in high-quality endocrine research in peripubertal adolescent girls.

Kisspeptin as a new serum biomarker to discriminate miscarriage from viable intrauterine pregnancy.

OBJECTIVE: To validate the ability of serum kisspeptin-54 to discriminate between first-trimester viable pregnancies and miscarriages. DESIGN: Case-control study. SETTING: Academic medical centers. PATIENT(S): Women with confirmed viable intrauterine pregnancy (IUP) at estimated gestational age 6-10 weeks (n = 20), women with confirmed miscarriage (spontaneous abortion [SAB]) at estimated gestational age 6-10 weeks (n = 20), and nonpregnant women (n = 19). INTERVENTION(S): Collection of serum samples from women with confirmed IUP, SAB, and nonpregnant women for the measurement of serum kisspeptin and serum hCG levels. MAIN OUTCOME MEASURE(S): Serum kisspeptin and hCG. RESULT(S): The limit of detection was 0.024 ng/mL; intra- and interassay coefficients of variation were 5.1% and 8.6%, respectively. Kisspeptin levels differed between the pregnant and nonpregnant state and by viability. Kisspeptin levels were positively associated with gestational age. There was also a significant positive association with hCG in SAB, but not in IUP. CONCLUSION(S): Plasma levels of kisspeptin have been suggested as a biomarker for miscarriage. This study demonstrates kisspeptin assay stability in serum and its potential clinical utility as a biomarker for early pregnancy viability.

Antimüllerian hormone levels and antral follicle counts are not reduced compared with community controls in patients with rigorously defined unexplained infertility.

OBJECTIVE: To test the hypothesis that women with unexplained infertility demonstrate evidence of diminished ovarian reserve when compared with a population of community controls. DESIGN: Cross-sectional study. SETTING: Multicenter university-based clinical practices. PATIENT(S): Study participants included 277 healthy, normo-ovulatory female partners with rigorously defined unexplained infertility randomly selected from a multicenter trial (Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation). Controls included 226 healthy, normo-ovulatory women not seeking treatment for fertility from a community-based cohort (Ovarian Aging study). INTERVENTION(S): Serum antimüllerian hormone (AMH) assay at a central laboratory, FSH, fasting serum metabolic testing, transvaginal ultrasonography for antral follicle counts (AFCs), anthropometric measurements. MAIN OUTCOME MEASURE(S): Average AMH, AFC, and AMH/AFC were compared between infertile and control women by age. Analyses of covariance compared these outcomes while controlling for confounders, including age, race, body mass index, smoking history, and study site. RESULT(S): In our models, AMH, AFC, and AMH/AFC ovarian reserve indices did not differ between infertile women and community-based controls, after controlling for age, race, body mass index, smoking history, and study site. CONCLUSION(S): Currently utilized predictors of ovarian reserve do not discriminate women with rigorously defined unexplained infertility from healthy community-based women of similar demographic characteristics. Contrary to our hypothesis, among women with FSH in the normal range (≤12 IU/L), women with unexplained infertility did not show evidence of decreased ovarian reserve as measured by AMH and AFC. Ovarian reserve markers in isolation may not serve as predictors of future fertility.

Acute Psychosocial Stress Inhibits LH Pulsatility and Kiss1 Neuronal Activation in Female Mice.

Psychosocial stress, such as isolation and restraint, disrupts reproductive neuroendocrine activity. Here we investigate the impact of psychosocial stress on luteinizing hormone (LH) pulses and gene expression and neuronal activation within Rfrp and Kiss1 cells in female mice. Mice were ovariectomized (OVX) and handled daily to habituate to the tail-tip blood collection procedure. Blood was collected every 5 minutes for 180 minutes for measurement of LH. After 90 minutes, stress animals were placed into restraint devices and isolated to new cages. No-stress control animals remained in their home cages. LH pulses occurred at regular intervals during the entire 180-minute sampling period in controls. In contrast, stress induced a rapid and robust suppression of pulsatile LH secretion. Stress reduced the frequency of pulses by 60% and diminished basal LH levels by 40%; pulse amplitude was unaffected. In a separate cohort of OVX females, brains were collected after 45, 90, or 180 minutes of stress or in no-stress controls. At all time points, stress induced a potent decrease in arcuate Kiss1 neuronal activation, using cfos induction as a marker, with a 50% to 60% suppression vs control levels, whereas Rfrp and cfos coexpression in the dorsal-medial nucleus was elevated after 45 minutes of stress. Although arcuate Kiss1 gene expression remained stable, Rfrp expression was elevated 20% after 180 minutes of stress. These findings demonstrate rapid suppression of LH pulsatile secretion by psychosocial stress, associated with reduced cfos induction in Kiss1 neurons and time-dependent increases in Rfrp neuronal activation and messenger RNA.

Age-stratified thresholds of anti-Müllerian hormone improve prediction of polycystic ovary syndrome over a population-based threshold.

OBJECTIVE: Due to its consistent elevation in polycystic ovary syndrome (PCOS) and correlation with polycystic ovarian morphology (PCOM), anti-Mullerian hormone (AMH) has been proposed as a marker of the syndrome. However, prior studies reporting thresholds of AMH for a PCOS diagnosis have been limited by small sample size, inappropriate controls, and heterogeneous AMH assays. We sought to evaluate the suitability of a standardized AMH assay as a biomarker of PCOS. DESIGN: Cross-sectional study at academic medical centres across the United States. PATIENTS: Women with PCOS were diagnosed by Rotterdam criteria and included 282 subjects from the multisite PPCOS II trial and 109 patients from a tertiary academic centre's multidisciplinary PCOS clinic. Controls included 245 participants in the ovarian ageing (OVA) study, a community-based cohort of ovulatory women not seeking treatment for fertility. MEASUREMENTS: Determination of AMH by a central laboratory. Receiver-operating characteristic (ROC) analyses were used to investigate the accuracy of AMH thresholds for prediction of PCOS diagnosis with stratification by age. RESULTS: The optimal threshold of AMH to distinguish PCOS from controls was 55.36 pmol/L (sensitivity: 0.82, specificity: 0.78, J: 0.60). When examining the population by age groups, the optimal AMH threshold decreased with increasing age. CONCLUSIONS: AMH is an effective biomarker of PCOS. Age-stratified thresholds more accurately predicted PCOS than an overall population-based threshold.

A microfluidic culture model of the human reproductive tract and 28-day menstrual cycle.

The endocrine system dynamically controls tissue differentiation and homeostasis, but has not been studied using dynamic tissue culture paradigms. Here we show that a microfluidic system supports murine ovarian follicles to produce the human 28-day menstrual cycle hormone profile, which controls human female reproductive tract and peripheral tissue dynamics in single, dual and multiple unit microfluidic platforms (Solo-MFP, Duet-MFP and Quintet-MPF, respectively). These systems simulate the in vivo female reproductive tract and the endocrine loops between organ modules for the ovary, fallopian tube, uterus, cervix and liver, with a sustained circulating flow between all tissues. The reproductive tract tissues and peripheral organs integrated into a microfluidic platform, termed EVATAR, represents a powerful new in vitro tool that allows organ-organ integration of hormonal signalling as a phenocopy of menstrual cycle and pregnancy-like endocrine loops and has great potential to be used in drug discovery and toxicology studies.

Letrozole versus clomiphene for infertility in the polycystic ovary syndrome.

BACKGROUND: Clomiphene is the current first-line infertility treatment in women with the polycystic ovary syndrome, but aromatase inhibitors, including letrozole, might result in better pregnancy outcomes. METHODS: In this double-blind, multicenter trial, we randomly assigned 750 women, in a 1:1 ratio, to receive letrozole or clomiphene for up to five treatment cycles, with visits to determine ovulation and pregnancy, followed by tracking of pregnancies. The polycystic ovary syndrome was defined according to modified Rotterdam criteria (anovulation with either hyperandrogenism or polycystic ovaries). Participants were 18 to 40 years of age, had at least one patent fallopian tube and a normal uterine cavity, and had a male partner with a sperm concentration of at least 14 million per milliliter; the women and their partners agreed to have regular intercourse with the intent of conception during the study. The primary outcome was live birth during the treatment period. RESULTS: Women who received letrozole had more cumulative live births than those who received clomiphene (103 of 374 [27.5%] vs. 72 of 376 [19.1%], P=0.007; rate ratio for live birth, 1.44; 95% confidence interval, 1.10 to 1.87) without significant differences in overall congenital anomalies, though there were four major congenital anomalies in the letrozole group versus one in the clomiphene group (P=0.65). The cumulative ovulation rate was higher with letrozole than with clomiphene (834 of 1352 treatment cycles [61.7%] vs. 688 of 1425 treatment cycles [48.3%], P<0.001). There were no significant between-group differences in pregnancy loss (49 of 154 pregnancies in the letrozole group [31.8%] and 30 of 103 pregnancies in the clomiphene group [29.1%]) or twin pregnancy (3.4% and 7.4%, respectively). Clomiphene was associated with a higher incidence of hot flushes, and letrozole was associated with higher incidences of fatigue and dizziness. Rates of other adverse events were similar in the two treatment groups. CONCLUSIONS: As compared with clomiphene, letrozole was associated with higher live-birth and ovulation rates among infertile women with the polycystic ovary syndrome. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others; ClinicalTrials.gov number, NCT00719186.).

The Pregnancy in Polycystic Ovary Syndrome II study: baseline characteristics and effects of obesity from a multicenter randomized clinical trial.

OBJECTIVE: To summarize baseline characteristics from a large multicenter infertility clinical trial. DESIGN: Cross-sectional baseline data from a double-blind randomized trial of two treatment regimens (letrozole vs. clomiphene). SETTING: Academic Health Centers throughout the United States. PATIENT(S): Seven hundred fifty women with polycystic ovary syndrome (PCOS) and their male partners took part in the study. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Historic, biometric, biochemical, and questionnaire parameters. RESULT(S): Females averaged 30 years and were obese (body mass index [BMI] 35) with ∼20% from a racial/ethnic minority. Most (87%) were hirsute and nulligravid (63%). Most of the women had an elevated antral follicle count and enlarged ovarian volume on ultrasound. Women had elevated mean circulating androgens, LH-to-FSH ratio (∼2), and antimüllerian hormone levels (8.0 ng/mL). In addition, women had evidence for metabolic dysfunction with elevated mean fasting insulin and dyslipidemia. Increasing obesity was associated with decreased LH-to-FSH levels, antimüllerian hormone levels, and antral follicle counts but increasing cardiovascular risk factors, including prevalence of the metabolic syndrome. Men were obese (BMI 30) and had normal mean semen parameters. CONCLUSION(S): The treatment groups were well matched at baseline. Obesity exacerbates select female reproductive and most metabolic parameters. We have also established a database and sample repository that will eventually be accessible to investigators. CLINICAL TRIAL REGISTRATION NUMBER: NCT00719186.

Estimation of estradiol in mouse serum samples: evaluation of commercial estradiol immunoassays.

The University of Virginia Center for Research in Reproduction Ligand Core performed an evaluation of nine commercial estradiol (E2) immunoassays for use with mouse serum. The evaluation had two components. 1) Recovery Studies: a mouse pool was spiked with E2 concentrations across the assay range, and percent recovery and parallelism to the assay standard curve were determined. 2) Correlation Studies: serum pools were collected from intact females, ovariectomized (OVX) and OVX-E2 treated mice and E2 assayed, then measured by gas chromatography/tandem mass spectrometry (GC/MSMS) for comparison to a gold standard method. Recovery results showed that E2 recovery from spiked mouse pools varied greatly (from <18% to >640%) among kits tested. However, three kits (DiaSorin Radioimmunoassay, Siemens Double Antibody RIA, and CalBiotech Enzyme Immunoassay) showed reasonable recoveries and parallelism. Data collected from the Correlation Study showed that values from intact, OVX and OVX-E2-treated mouse pools varied by several fold vs. GC/MSMS for most of the kits tested. The DiaSorin RIA and CalBiotech Enzyme Immunoassay Kits showed the best correlation to GC/MSMS. Unfortunately, while this evaluation was ongoing, the DiaSorin Kit was discontinued. In summary, the CalBiotech Kit was the only available assay tested that demonstrated good E2 parallelism to the assay standard curve and accuracy vs. a gold standard method (i.e. GC/MSMS). Also of note, the CalBiotech assay is sensitive and requires minimal sample volume. Therefore, based on these findings the CalBiotech E2 assay has been implemented for use in mouse serum samples within the Ligand Core.

GnRH pulse frequency differentially regulates steroidogenic factor 1 (SF1), dosage-sensitive sex reversal-AHC critical region on the X chromosome gene 1 (DAX1), and serum response factor (SRF): potential mechanism for GnRH pulse frequency regulation of LH beta transcription in the rat.

The issue of how rapid frequency GnRH pulses selectively stimulate LH transcription is not fully understood. The rat LHß promoter contains two GnRH-responsive regions: the proximal region has binding elements for SF1, and the distal site contains a CArG box, which binds SRF. This study determined whether GnRH stimulates pituitary SF1, DAX1 (an endogenous SF1 inhibitor), and SRF transcription in vivo, and whether regulation is frequency dependent. Male rats were pulsed with 25 ng GnRH i.v. every 30 min or every 240 min for 1-24 h, and primary transcripts (PTs) and mRNAs were measured by real time PCR. Fast frequency GnRH pulses (every 30 min) increased SF1 PT (threefold) within 1 h, and then declined after 6 h. SF1 mRNA also increased within 1 h and remained elevated through 24 h. Fast frequency GnRH also stimulated a transient increase in DAX1 PT (twofold after 1 h) and mRNA (1.7-fold after 6 h), while SRF mRNA rose briefly at 1 h. Slow frequency pulses did not affect gene expression of SF1, DAX1, or SRF. These findings support a mechanistic link between SF1 in the frequency regulation of LHß transcription by pulsatile GnRH.

Regulation of Lhb and Egr1 gene expression by GNRH pulses in rat pituitaries is both c-Jun N-terminal kinase (JNK)- and extracellular signal-regulated kinase (ERK)-dependent.

Pulsatile GNRH regulates the gonadotropin subunit genes in a differential manner, with faster frequencies favoring Lhb gene expression and slower frequencies favoring Fshb. Early growth response 1 (EGR1) is critical for Lhb gene transcription. We examined GNRH regulation of EGR1 and its two corepressors, Ngfi-A-binding proteins 1 and 2 (NAB1 and NAB2), both in vivo and in cultured rat pituitary cells. In rats, fast GNRH pulses (every 30 min) stably induced Egr1 primary transcript (PT) and mRNA 2-fold (P < 0.05) for 1-24 h. In contrast, slow GNRH pulses (every 240 min) increased Egr1 PT at 24 h (6-fold; P < 0.05) but increased Egr1 mRNA 4- to 5-fold between 4 and 24 h. Both GNRH pulse frequencies increased EGR1 protein 3- to 4-fold. In cultured rat pituitary cells, GNRH pulses (every 60 min) increased Egr1 (PT, 2.5- to 3-fold; mRNA, 1.5- to 2-fold; P < 0.05). GNRH pulses had little effect on Nab1/2 PT/mRNAs either in vivo or in vitro. We also examined specific intracellular signaling cascades activated by GNRH. Inhibitors of mitogen-activated protein kinase 8/9 (MAPK8/9 [also known as JNK]; SP600125) and MAP Kinase Kinase 1 (MAP2K1 [also known as MEK1]; PD98059) either blunted or totally suppressed the GNRH induction of Lhb PT and Egr1 PT/mRNA, whereas the MAPK14 (also known as p38) inhibitor SB203580 did not. In summary, pulsatile GNRH stimulates Egr1 gene expression and protein in vivo but not in a frequency-dependent manner. Additionally, GNRH-induced Egr1 gene expression is mediated by MAPK8/9 and MAPK1/3, and both are critical for Lhb gene transcription.

Regulation of intracellular signaling cascades by GNRH pulse frequency in the rat pituitary: roles for CaMK II, ERK, and JNK activation.

Pulsatile GnRH (GNRH) differentially regulates LH and FSH subunit genes, with faster frequencies favoring Lhb transcription and slower favoring Fshb. Various intracellular pathways mediate the effects of GNRH, including CaMK II (CAMK2), ERK, and JNK. We examined whether activation of these pathways is regulated by GNRH pulse frequency in vivo. GNRH-deficient rats received GNRH pulses (25 ng i.v. every 30 or 240 min for 8 h, vehicle to controls). Pituitaries were collected 5 min after the last pulse, bisected, and one half processed for RNA (to measure beta subunit primary transcripts [PTs]) and the other for protein. Phosphorylated CAMK2 (phospho-CAMK2), ERK (mitogen-activated protein kinase 1/3 [MAPK1/3], also known as p42 ERK2 and p44 ERK1, respectively), and JNK (MAPK8/9, also known as p46 JNK1 and p54 JNK2, respectively) were determined by Western blotting. The 30-min pulses maximally stimulated Lhb PT (8-fold), whereas 240 min was optimal for Fshb PT (3-fold increase). Both GNRH pulse frequencies increased phospho-CAMK2 4-fold. Activation of MAPK1/3 was stimulated by both 30- and 240-min pulses, but phosphorylation of MAPK3 was significantly greater following slower GNRH pulses (240 min: 4-fold, 30 min: 2-fold). MAPK8/9 activation was unchanged by pulsatile GNRH in this paradigm, but as previous results showed that GNRH-induced activation of MAPK8/9 is delayed, 5 min after GNRH may not be optimal to observe MAPK8/9 activation. These data show that CAMK2 is activated by GNRH, but not in a frequency-dependant manner, whereas MAPK3 is maximally stimulated by slow-frequency GNRH pulses. Thus, the ERK response to slow pulse frequency is part of the mechanisms mediating Fhb transcriptional responses to GNRH.