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pulsatile hormone secretion

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https://www.readbyqxmd.com/read/28808344/hypothalamic-effects-of-progesterone-on-regulation-of-the-pulsatile-and-surge-release-of-luteinising-hormone-in-female-rats
#1
Wen He, Xiaofeng Li, Daniel Adekunbi, Yali Liu, Hui Long, Li Wang, Qifeng Lyu, Yanping Kuang, Kevin T O'Byrne
Progesterone can block the oestradiol-induced GnRH/LH surge and inhibit LH pulse frequency. Recent studies reported that progesterone prevented premature LH surges during ovarian hyperstimulation in women. As the most potent stimulator of GnRH/LH release, kisspeptin is believed to mediate the positive and negative feedback effects of oestradiol in the hypothalamic anteroventral periventricular (AVPV) and arcuate (ARC) nuclei, while the region-specific role of progesterone receptors in these nuclei remains unknown...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28804622/human-placental-growth-hormone-in-normal-and-abnormal-fetal-growth
#2
Alexandros Velegrakis, Maria Sfakiotaki, Stavros Sifakis
Human placental growth hormone (PGH), encoded by the growth hormone (GH) variant gene on chromosome 17, is expressed in the syncytiotrophoblast and extravillous cytotrophoblast layers of the human placenta. Its maternal serum levels increase throughout pregnancy, and gradually replaces the pulsatile secreted pituitary GH. PGH is also detectable in cord blood and in the amniotic fluid. This placental-origin hormone stimulates glyconeogenesis, lipolysis and anabolism in maternal organs, and influences fetal growth, placental development and maternal adaptation to pregnancy...
August 2017: Biomedical Reports
https://www.readbyqxmd.com/read/28802064/neurokinin-3-receptor-antagonism-decreases-gonadotropin-and-testosterone-secretion-in-healthy-men
#3
Karolina Skorupskaite, Jyothis T George, Johannes D Veldhuis, Robert P Millar, Richard A Anderson
OBJECTIVE: Patients with mutations of NKB and its receptor show hypogonadotrophic hypogonadism, but there is little evidence for the importance of this pathway in reproductive function in normal men, or its functional hierarchy with kisspeptin. DESIGN: An open label study wherein men (n=6) were administered the NK3R antagonist MLE4901 40mg orally twice a day for 7 days. Kisspeptin-10 (0.3 μg/kg iv bolus) was given before and on day 7 of NK3R antagonist treatment...
August 12, 2017: Clinical Endocrinology
https://www.readbyqxmd.com/read/28800500/sb223412-a-neurokinin-3-receptor-selective-antagonist-suppresses-testosterone-secretion-in-male-guinea-pigs
#4
Sho Nakamura, Yoshiko Ito, Koki Yamamoto, Chudai Takahashi, Mingdao Dai, Miyu Tanahashi, Yoshihisa Uenoyama, Hiroko Tsukamura, Shinya Oishi, Kei-Ichiro Maeda, Fuko Matsuda
Guinea pigs are important zoo animals and have been recommended for animal-assisted activities or therapy, however there are problems concerning testosterone inducing aggressive or sexual behaviors in male guinea pigs. Testicular testosterone secretion is regulated by pulsatile gonadotropin releasing hormone (GnRH)/luteinizing hormone (LH) release in mammals. The mechanism generating GnRH/LH pulses is thought to be governed by kisspeptin neurons, which coexpress neurokinin B (NKB) and dynorphin A (Dyn), in the arcuate nucleus (ARC)...
July 31, 2017: Theriogenology
https://www.readbyqxmd.com/read/28800490/oxytocin-secretion-is-pulsatile-in-men-and-is-related-to-social-emotional-functioning
#5
Charumathi Baskaran, Franziska Plessow, Lisseth Silva, Elisa Asanza, Dean Marengi, Kamryn T Eddy, Patrick M Sluss, Michael L Johnson, Madhusmita Misra, Elizabeth A Lawson
The hypothalamic hormone oxytocin (OXT) plays an important role in a range of physiological processes and social-emotional functioning in both sexes. In women, physiological stimuli, such as suckling and parturition, result in pulsatile release of OXT into the peripheral circulation via the posterior pituitary gland. However, data regarding OXT secretory patterns in men during a state of rest are limited. Further, the relationship between secretory dynamics of OXT and emotional measures has never been evaluated...
July 24, 2017: Psychoneuroendocrinology
https://www.readbyqxmd.com/read/28790978/progress-and-challenges-in-the-search-for-the-mechanisms-of-pulsatile-gonadotropin-releasing-hormone-secretion
#6
REVIEW
Stephanie Constantin
Fertility relies on the proper functioning of the hypothalamic-pituitary-gonadal axis. The hormonal cascade begins with hypothalamic neurons secreting gonadotropin-releasing hormone (GnRH) into the hypophyseal portal system. In turn, the GnRH-activated gonadotrophs in the anterior pituitary release gonadotropins, which then act on the gonads to regulate gametogenesis and sex steroidogenesis. Finally, sex steroids close this axis by feeding back to the hypothalamus. Despite this seeming straightforwardness, the axis is orchestrated by a complex neuronal network in the central nervous system...
2017: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/28760599/gonadotropin-releasing-hormone-signaling-an-information-theoretic-approach
#7
REVIEW
Margaritis Voliotis, Kathryn L Garner, Hussah Alobaid, Krasimira Tsaneva-Atanasova, Craig A McArdle
Gonadotropin-releasing hormone (GnRH) is a peptide hormone that mediates central control of reproduction, acting via G-protein coupled receptors that are primarily Gq coupled and mediate GnRH effects on the synthesis and secretion of luteinizing hormone and follicle-stimulating hormone. A great deal is known about the GnRH receptor signaling network but GnRH is secreted in short pulses and much less is known about how gonadotropes decode this pulsatile signal. Similarly, single cell measures reveal considerable cell-cell heterogeneity in responses to GnRH but the impact of this variability on signaling is largely unknown...
July 29, 2017: Molecular and Cellular Endocrinology
https://www.readbyqxmd.com/read/28497294/a-two-step-deconvolution-analysis-informed-population-pharmacodynamic-modeling-approach-for-drugs-targeting-pulsatile-endogenous-compounds
#8
Michiel J van Esdonk, Jacobus Burggraaf, Piet H van der Graaf, Jasper Stevens
Pharmacodynamic modeling of pulsatile endogenous compounds (e.g. growth hormone [GH]) is currently limited to the identification of a low number of pulses. Commonly used pharmacodynamic models are not able to capture the complexity of pulsatile secretion and therefore non-compartmental analyses are performed to extract summary statistics (mean, AUC, Cmax). The aim of this study was to develop a new quantification method that deals with highly variable pulsatile data by using a deconvolution-analysis-informed population pharmacodynamic modeling approach...
August 2017: Journal of Pharmacokinetics and Pharmacodynamics
https://www.readbyqxmd.com/read/28475285/evidence-of-involvement-of-neurone-glia-neurone-neurone-communications-via-gap-junctions-in-synchronised-activity-of-kndy-neurones
#9
K Ikegami, S Minabe, N Ieda, T Goto, A Sugimoto, S Nakamura, N Inoue, S Oishi, A D Maturana, M Sanbo, M Hirabayashi, K-I Maeda, H Tsukamura, Y Uenoyama
Pulsatile secretion of gonadotrophin-releasing hormone (GnRH)/luteinising hormone is indispensable for the onset of puberty and reproductive activities at adulthood in mammalian species. A cohort of neurones expressing three neuropeptides, namely kisspeptin, encoded by the Kiss1 gene, neurokinin B (NKB) and dynorphin A, localised in the hypothalamic arcuate nucleus (ARC), so-called KNDy neurones, comprises a putative intrinsic source of the GnRH pulse generator. Synchronous activity among KNDy neurones is considered to be required for pulsatile GnRH secretion...
June 2017: Journal of Neuroendocrinology
https://www.readbyqxmd.com/read/28447478/pulsatile-kisspeptin-effectively-stimulates-gonadotropin-releasing-hormone-gnrh-producing-neurons
#10
Haruhiko Kanasaki, Mijiddorj Tselmeg, Aki Oride, Unurjargal Sukhbaatar, Tomomi Hara, Satoru Kyo
Hypothalamic kisspeptin is integral to the hypothalamic-pituitary-gonadal axis by stimulating gonadotropin-releasing hormone (GnRH) release. GnRH is released from the hypothalamus in a pulsatile manner and determines the output of the gonadotropins. However, the effect of kisspeptin on GnRH-secreting cells remains unknown. In an experiment using static cultures of GT1-7 cells, kisspeptin did not significantly increase GnRH mRNA expression. However, when kisspeptin was administered to the cells in a pulsatile manner, GnRH mRNA expression was significantly increased...
April 27, 2017: Gynecological Endocrinology
https://www.readbyqxmd.com/read/28404685/rising-maternal-circulating-gh-during-murine-pregnancy-suggests-placental-regulation
#11
Kathryn L Gatford, Beverly S Muhlhausler, Lili Huang, Pamela Su-Lin Sim, Claire T Roberts, Johannes D Velhuis, Chen Chen
Placenta-derived hormones including growth hormone (GH) in humans contribute to maternal adaptation to pregnancy, and intermittent maternal GH administration increases foetal growth in several species. Both patterns and abundance of circulating GH are important for its activity, but their changes during pregnancy have only been reported in humans and rats. The aim of the present study was to characterise circulating profiles and secretory characteristics of GH in non-pregnant female mice and throughout murine pregnancy...
May 2017: Endocrine Connections
https://www.readbyqxmd.com/read/28377404/effect-of-androgen-on-kiss1-expression-and-luteinizing-hormone-release-in-female-rats
#12
Kinuyo Iwata, Yuyu Kunimura, Keisuke Matsumoto, Hitoshi Ozawa
Hyperandrogenic women have various grades of ovulatory dysfunction, which lead to infertility. The purpose of this study was to determine whether chronic exposure to androgen affects expression of kisspeptin (ovulation and follicle development regulator) or release of luteinizing hormone (LH) in female rats. Weaned females were subcutaneously implanted with 90-day continuous-release pellets of 5α-dihydrotestosterone (DHT) and studied after 10 weeks of age. Number of Kiss1-expressing cells in both the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) was significantly decreased in ovary-intact DHT rats...
April 4, 2017: Journal of Endocrinology
https://www.readbyqxmd.com/read/28368521/regulation-of-pulsatile-and-entropic-acth-secretion-under-fixed-exogenous-secretagogue-clamps
#13
Ferdinand Roelfsema, Paul Aoun, Paul Y Takahashi, Dana Erickson, Rebecca Yang, Johannes D Veldhuis
Background: Studies of ACTH secretion are hampered by unobservable hypothalamic CRH and AVP pulses. Clamping one of the secretagogues could allow indirect quantification of the impact of the endogenous heterotypic hormone. Methods: Randomized, double-blind, placebo-controlled cross-over study in 28 healthy adults (16 men), mean age 55 yr. Volunteers received leuprolide, followed by placebo or sex-steroid addback. Eucortisolemia was accomplished by oral ketoconazole and continuous iv cortisol administration with 10 h of 10-min sampling...
March 28, 2017: Journal of Clinical Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28328155/does-dynorphin-play-a-role-in-the-onset-of-puberty-in-female-sheep
#14
J A Lopez, M N Bedenbaugh, R B McCosh, P W Weems, L J Meadows, B Wisman, L M Coolen, R L Goodman, S M Hileman
Puberty onset involves increased gonadotrophin-release (GnRH) release as a result of decreased sensitivity to oestrogen (E2 )-negative feedback. Because GnRH neurones lack E2 receptor α, this pathway must contain interneurones. One likely candidate is KNDy neurones (kisspeptin, neurokinin B, dynorphin). The overarching hypothesis of the present study was that the prepubertal hiatus in luteinising hormone (LH) release involves reduced kisspeptin and/or heightened dynorphin input. We first tested the specific hypothesis that E2 would reduce kisspeptin-immunopositive cell numbers and increase dynorphin-immunopositive cell numbers...
December 2016: Journal of Neuroendocrinology
https://www.readbyqxmd.com/read/28324006/effects-of-season-and-estradiol-on-kndy-neuron-peptides-colocalization-with-d2-dopamine-receptors-and-dopaminergic-inputs-in-the-ewe
#15
Peyton Weems, Jeremy Smith, Iain J Clarke, Lique M Coolen, Robert L Goodman, Michael N Lehman
Seasonal reproduction in sheep is primarily due to a dramatic increase in the ability of estradiol (E2) to inhibit the pulsatile secretion of gonadotropin-releasing hormone (GnRH) during the nonbreeding season [anestrus (ANS)]. Recent findings suggest that kisspeptin/neurokinin B/dynorphin (KNDy) neurons of the arcuate nucleus (ARC) play a key role in conveying this negative feedback influence, with dopaminergic projections from the retrochiasmatic area acting upon KNDy cells to decrease kisspeptin release and thus inhibit GnRH pulses...
April 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/28323953/activation-of-male-liver-chromatin-accessibility-and-stat5-dependent-gene-transcription-by-plasma-growth-hormone-pulses
#16
Jeannette Connerney, Dana Lau-Corona, Andy Rampersaud, David J Waxman
Sex-differences in pituitary growth hormone (GH) secretion (pulsatile in males vs near continuous/persistent in females) impart sex-dependent expression to hundreds of genes in adult mouse liver. STAT5, a GH-activated transcription factor that is essential for liver sexual dimorphism, is dynamically activated in direct response to each male plasma GH pulse. However, the impact of GH-induced STAT5 pulses on liver chromatin accessibility and downstream transcriptional events is unknown. Here, we investigate the impact of a single pulse of GH given to hypophysectomized mice on local liver chromatin accessibility [DNase hypersensitive site analysis], transcription rates [hnRNA analysis], and gene expression [quantitative PCR and RNA-Seq] determined 30, 90 or 240 min later...
February 17, 2017: Endocrinology
https://www.readbyqxmd.com/read/28285644/effects-of-transdermal-testosterone-gel-or-an-aromatase-inhibitor-on-serum-concentration-and-pulsatility-of-growth-hormone-in-older-men-with-age-related-low-testosterone
#17
RANDOMIZED CONTROLLED TRIAL
Jenny Pena Dias, Johannes D Veldhuis, Olga Carlson, Michelle Shardell, Chee W Chia, Denise Melvin, Josephine M Egan, Shehzad Basaria
Growth hormone is the major regulator of growth and body composition. Pulsatile GH secretion declines exponentially with age. Testosterone replacement is being increasingly offered to older men with age-related low testosterone. Testosterone administration has been shown to stimulate GH secretion. However, little is known about the effect of testosterone aromatization to estradiol on GH pulsatility and its impact on IGF-1 in older men. OBJECTIVE: This randomized controlled proof-of-concept trial investigated the relative effects of testosterone and estradiol on GH pulsatility and IGF-1 in older men with low testosterone...
April 2017: Metabolism: Clinical and Experimental
https://www.readbyqxmd.com/read/28275169/mode-of-gh-administration-and-gene-expression-in-the-female-rat-brain
#18
Marion Walser, Linus Schiöler, Jan Oscarsson, Maria A I Åberg, Ruth Wickelgren, Johan Svensson, Jörgen Isgaard, N David Åberg
The endogenous secretion of growth hormone (GH) is sexually dimorphic in rats with females having a more even and males a more pulsatile secretion and low trough levels. The mode of GH administration, mimicking the sexually dimorphic secretion, has different systemic effects. In the brains of male rats, we have previously found that the mode of GH administration differently affects neuron-haemoglobin beta (Hbb) expression whereas effects on other transcripts were moderate. The different modes of GH administration could have different effects on brain transcripts in female rats...
May 2017: Journal of Endocrinology
https://www.readbyqxmd.com/read/28003536/deficient-melanocortin-4-receptor-causes-abnormal-reproductive-neuroendocrine-profile-in-female-mice
#19
Xiaolin Chen, Lili Huang, Hwee Y Tan, Hongzhuo Li, Ying Wan, Michael Cowley, Johannes D Veldhuis, Chen Chen
Deletion of the melanocortin-4-receptor (Mc4r) gene in mice causes hyperphagia, followed by hyperinsulinemia, obesity and progressive infertility. Evidence shows that the number of developed corpora lutea is reduced in obese MC4R-knockout (MC4R KO) female mice, but the mechanism is unclear. The effect of hyperphagia and obesity by MC4R KO on pulsatile luteinizing hormone (LH) secretion and ovulation remains unknown. In MC4R KO mice and wild-type littermates (WT LM) during the diestrus period throughout different ages, we examined and monitored their metabolic status, pulsatile LH profiles, follicular morphology and the number of corpora lutea...
March 2017: Reproduction: the Official Journal of the Society for the Study of Fertility
https://www.readbyqxmd.com/read/27989866/localization-and-expression-of-molt-inhibiting-hormone-and-nitric-oxide-synthase-in-the-central-nervous-system-of-the-green-shore-crab-carcinus-maenas-and-the-blackback-land-crab-gecarcinus-lateralis
#20
COMPARATIVE STUDY
Natalie L Pitts, Donald L Mykles
In decapod crustaceans, molting is controlled by the pulsatile release of molt-inhibiting hormone (MIH) from neurosecretory cells in the X-organ/sinus gland (XO/SG) complex in the eyestalk ganglia (ESG). A drop in MIH release triggers molting by activating the molting gland or Y-organ (YO). Post-transcriptional mechanisms ultimately control MIH levels in the hemolymph. Neurotransmitter-mediated electrical activity controls Ca(2+)-dependent vesicular release of MIH from the SG axon terminals, which may be modulated by nitric oxide (NO)...
January 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
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