32 research outputs found

    Intracerebroventricular Infusion of Vasoactive Intestinal Peptide Rescues the Luteinizing Hormone Surge in Middle-Aged Female Rats

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    Reproductive aging is characterized by delayed and attenuated luteinizing hormone (LH) surges apparent in middle-aged rats. The suprachiasmatic nucleus (SCN) contains the circadian clock that is responsible for the timing of diverse neuroendocrine rhythms. Electrophysiological studies suggest vasoactive intestinal peptide (VIP) originating from the SCN excites gonadotropin-releasing hormone (GnRH) neurons and affects daily patterns of GnRH–LH release. Age-related LH surge dysfunction correlates with reduced VIP mRNA expression in the SCN and fewer GnRH neurons with VIP contacts expressing c-fos, a marker of neuronal activation, on the day of the LH surge. To determine if age-related LH surge dysfunction reflects reduced VIP availability or altered VIP responsiveness under estradiol positive feedback conditions, we assessed the effect of intracerebroventricular (icv) VIP infusion on c-fos expression in GnRH neurons and on LH release in ovariohysterectomized, hormone-primed young and middle-aged rats. Icv infusion of VIP between 1300 and 1600 h significantly advanced the time of peak LH release, increased total and peak LH release, and increased the number of GnRH neurons expressing c-fos on the day of the LH surge in middle-aged rats. Surprisingly, icv infusion of VIP in young females significantly reduced the number of GnRH neurons expressing c-fos and delayed and reduced the LH surge. These observations suggest that a critical balance of VIP signaling is required to activate GnRH neurons for an appropriately timed and robust LH surge in young and middle-aged females. Age-related LH surge changes may, in part, result from decreased availability and reduced VIP-mediated neurotransmission under estradiol positive feedback conditions

    Characterization of Vascular Disease Risk in Postmenopausal Women and Its Association with Cognitive Performance

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    Objectives: While global measures of cardiovascular (CV) risk are used to guide prevention and treatment decisions, these estimates fail to account for the considerable interindividual variability in pre-clinical risk status. This study investigated heterogeneity in CV risk factor profiles and its association with demographic, genetic, and cognitive variables. Methods: A latent profile analysis was applied to data from 727 recently postmenopausal women enrolled in the Kronos Early Estrogen Prevention Study (KEEPS). Women were cognitively healthy, within three years of their last menstrual period, and free of current or past CV disease. Education level, apolipoprotein E ε4 allele (APOE4), ethnicity, and age were modeled as predictors of latent class membership. The association between class membership, characterizing CV risk profiles, and performance on five cognitive factors was examined. A supervised random forest algorithm with a 10-fold cross-validation estimator was used to test accuracy of CV risk classification. Results: The best-fitting model generated two distinct phenotypic classes of CV risk 62% of women were “low-risk” and 38% “high-risk”. Women classified as low-risk outperformed high-risk women on language and mental flexibility tasks (p = 0.008) and a global measure of cognition (p = 0.029). Women with a college degree or above were more likely to be in the low-risk class (OR = 1.595, p = 0.044). Older age and a Hispanic ethnicity increased the probability of being at high-risk (OR = 1.140, p = 0.002; OR = 2.622, p = 0.012; respectively). The prevalence rate of APOE-ε4 was higher in the high-risk class compared with rates in the low-risk class. Conclusion: Among recently menopausal women, significant heterogeneity in CV risk is associated with education level, age, ethnicity, and genetic indicators. The model-based latent classes were also associated with cognitive function. These differences may point to phenotypes for CV disease risk. Evaluating the evolution of phenotypes could in turn clarify preclinical disease, and screening and preventive strategies

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

    Restoration of the Luteinizing Hormone Surge in Middle-Aged Female Rats by Altering the Balance of GABA and Glutamate Transmission in the Medial Preoptic Area1

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    Hypothalamic glutamate and gamma-aminobutyric acid (GABA) neurotransmission are involved in the ovarian hormone-induced GnRH-LH surge in rodents. We previously reported that middle-aged rats have significantly less glutamate release in the medial preoptic area than young rats on the day of the LH surge. The present study tested the hypothesis that the delayed and attenuated LH surge in ovariohysterectomized middle-aged rats primed with ovarian steroids results from reduced hypothalamic glutamate and increased GABAA neurotransmission. Microdialysis results show that middle-aged rats with attenuated LH surges had reduced extracellular glutamate and increased extracellular GABA levels in the medial preoptic area compared with young rats. Blocking GABAA receptors with bicuculline or inhibiting synaptic glutamate reuptake with l-trans-pyrrolidine-2,4-dicarboxylic acid increased extracellular Glu in the medial preoptic area and partially restored LH surge amplitude in middle-aged rats without altering LH surge onset. Complete recovery of LH surge amplitude was observed in middle-aged rats treated with the combination of bicuculline and l-trans-pyrrolidine-2,4-dicarboxylic acid. This treatment also restored the extracellular glutamate:GABA ratio in the medial preoptic area of middle-aged rats to the level of young rats. Immunoblot analysis revealed that estradiol and progesterone treatment reduced SLC32A1(formerly known as vesicular GABA transporter) levels and increased SLC17A6 (formerly known as vesicular glutamate transporter 2) levels in the anterior hypothalamus of ovariohysterectomized young but not middle-aged rats. These data suggest that both reduced availability of glutamate and increased activation of GABAA receptors under estrogen-positive feedback conditions contribute to the age-related delay in onset and attenuated amplitude of the LH surge.

    Sex hormones in women with and without migraine: Evidence of migraine-specific hormone profiles

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    OBJECTIVE: To compare daily sex hormone levels and rates of change between women with history of migraine and controls. METHODS: History of migraine, daily headache diaries, and daily hormone data were collected in ovulatory cycles of pre- and early perimenopausal women in the Study of Women\u27s Health Across the Nation. Peak hormone levels, average daily levels, and within-woman day-to-day rates of decline over the 5 days following each hormone peak were calculated in ovulatory cycles for conjugated urinary estrogens (E1c), pregnanediol-3-glucuronide, luteinizing hormone, and follicle-stimulating hormone. Comparisons were made between migraineurs and controls using 2-sample t tests on the log scale with results reported as geometric means. RESULTS: The sample included 114 women with history of migraine and 223 controls. Analyses of within-woman rates of decline showed that E1c decline over the 2 days following the luteal peak was greater in migraineurs for both absolute rate of decline (33.8 [95% confidence interval 28.0-40.8] pg/mgCr vs 23.1 [95% confidence interval 20.1-26.6] pg/mgCr, p = 0.002) and percent change (40% vs 30%, p \u3c 0.001). There was no significant difference between migraineurs and controls in absolute peak or daily E1c, pregnanediol-3-glucuronide, luteinizing hormone, and follicle-stimulating hormone levels. Secondary analyses demonstrated that, among migraineurs, the rate of E1c decline did not differ according to whether a headache occurred during the cycle studied. CONCLUSIONS: Migraineurs are characterized by faster late luteal phase E1c decline compared to controls. The timing and rate of estrogen withdrawal before menses may be a marker of neuroendocrine vulnerability in women with migraine

    Effects of Hormone Therapy on Cognition and Mood in Recently Postmenopausal Women: Findings from the Randomized, Controlled KEEPS–Cognitive and Affective Study

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    Background: Menopausal hormone therapy (MHT) reportedly increases the risk of cognitive decline in women over age 65 y. It is unknown whether similar risks exist for recently postmenopausal women, and whether MHT affects mood in younger women. The ancillary Cognitive and Affective Study (KEEPS-Cog) of the Kronos Early Estrogen Prevention Study (KEEPS) examined the effects of up to 4 y of MHT on cognition and mood in recently postmenopausal women. Methods and Findings: KEEPS, a randomized, double-blinded, placebo-controlled clinical trial, was conducted at nine US academic centers. Of the 727 women enrolled in KEEPS, 693 (95.3%) participated in the ancillary KEEPS-Cog, with 220 women randomized to receive 4 y of 0.45 mg/d oral conjugated equine estrogens (o-CEE) plus 200 mg/d micronized progesterone (m-P) for the first 12 d of each month, 211 women randomized to receive 50 μg/d transdermal estradiol (t-E2) plus 200 mg/d m-P for the first 12 d of each month, and 262 women randomized to receive placebo pills and patches. Primary outcomes included the Modified Mini-Mental State examination; four cognitive factors: verbal learning/memory, auditory attention/working memory, visual attention/executive function, and speeded language/mental flexibility; and a mood measure, the Profile of Mood States (POMS). MHT effects were analyzed using linear mixed-effects (LME) models, which make full use of all available data from each participant, including those with missing data. Data from those with and without full data were compared to assess for potential biases resulting from missing observations. For statistically significant results, we calculated effect sizes (ESs) to evaluate the magnitude of changes. On average, participants were 52.6 y old, and 1.4 y past their last menstrual period. By month 48, 169 (24.4%) and 158 (22.8%) of the 693 women who consented for ancillary KEEPS-Cog were lost to follow-up for cognitive assessment (3MS and cognitive factors) and mood evaluations (POMS), respectively. However, because LME models make full use all available data, including data from women with missing data, 95.5% of participants were included in the final analysis (n = 662 in cognitive analyses, and n = 661 in mood analyses). To be included in analyses, women must have provided baseline data, and data from at least one post-baseline visit. The mean length of follow-up was 2.85 y (standard deviation [SD] = 0.49) for cognitive outcomes and 2.76 (SD = 0.57) for mood outcomes. No treatment-related benefits were found on cognitive outcomes. For mood, model estimates indicated that women treated with o-CEE showed improvements in depression and anxiety symptoms over the 48 mo of treatment, compared to women on placebo. The model estimate for the depression subscale was −5.36 × 10−2 (95% CI, −8.27 × 10−2 to −2.44 × 10−2; ES = 0.49, p < 0.001) and for the anxiety subscale was −3.01 × 10−2 (95% CI, −5.09 × 10−2 to −9.34 × 10−3; ES = 0.26, p < 0.001). Mood outcomes for women randomized to t-E2 were similar to those for women on placebo. Importantly, the KEEPS-Cog results cannot be extrapolated to treatment longer than 4 y. Conclusions: The KEEPS-Cog findings suggest that for recently postmenopausal women, MHT did not alter cognition as hypothesized. However, beneficial mood effects with small to medium ESs were noted with 4 y of o-CEE, but not with 4 y of t-E2. The generalizability of these findings is limited to recently postmenopausal women with low cardiovascular risk profiles. Trial Registration ClinicalTrials.gov NCT00154180 and NCT0062331
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