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pulsatile hormone secretion

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https://www.readbyqxmd.com/read/28404685/rising-maternal-circulating-gh-during-murine-pregnancy-suggests-placental-regulation
#1
Kathryn L Gatford, Beverly Muhlhausler, Lili Huang, Pamela S-L Sim, Claire T Roberts, Johannes D Veldhuis, Chen Chen
Placenta-derived hormones including growth hormone (GH) in humans contribute to maternal adaptation to pregnancy, and intermittent maternal GH administration increases fetal 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...
April 12, 2017: Endocrine Connections
https://www.readbyqxmd.com/read/28377404/effect-of-androgen-on-kiss1-expression-and-luteinizing-hormone-release-in-female-rats
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
Marion Walser, Linus Schiöler, Jan Oscarsson, Maria A I Åberg, Ruth Wickelgren, Johan Svensson, Jörgen Isgaard, N David Aberg
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...
March 8, 2017: Journal of Endocrinology
https://www.readbyqxmd.com/read/28003536/deficient-melanocortin-4-receptor-causes-abnormal-reproductive-neuroendocrine-profile-in-female-mice
#9
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
#10
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)...
October 27, 2016: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/27983870/kisspeptin-in-the-hypothalamus-of-2-rat-models-of-polycystic-ovary-syndrome
#11
Satoko Osuka, Akira Iwase, Tatsuo Nakahara, Mika Kondo, Ai Saito, Bayasula, Tomoko Nakamura, Sachiko Takikawa, Maki Goto, Tomomi Kotani, Fumitaka Kikkawa
Hyperandrogenism, disturbance of the hypothalamus-pituitary-ovary axis followed by elevated serum luteinizing hormone (LH) levels, and insulin resistance are involved in the complicated pathophysiology of polycystic ovary syndrome (PCOS). Kisspeptin is coexpressed with neurokinin B (NKB) in the arcuate nucleus (ARC), the center of the gonadotropin-releasing hormone pulse generator that is responsible for pulsatile LH secretion. We compared 2 androgenized rat models of PCOS to evaluate the estrous cycle, hormonal profiles, and expression of kisspeptin and NKB in the ARC...
February 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/27793455/effects-of-long-acting-gnrh-antagonist-degarelix-acetate-on-plasma-insulin-like-peptide-3-testosterone-and-luteinizing-hormone-concentrations-and-scrotal-circumference-in-male-goats
#12
M A Hannan, N Kawate, Y Fukami, W W P N Weerakoon, E E Büllesbach, T Inaba, H Tamada
We recently reported that plasma insulin-like peptide 3 (INSL3) concentrations increased soon after endogenous and exogenous stimulations of LH in male goats and bulls. However, the effects of LH suppression on INSL3 secretion are unknown in domestic animals. Here, we examined the effects of a long-acting GnRH antagonist (degarelix acetate; 4 mg/kg) on the secretions of plasma INSL3 and testosterone in two phases, an immediate and a long-term phase in male goats (n = 6; aged, 13-16 months). During the immediate phase, blood was taken at 15-minute intervals for 8 hours on Days -5, 0, and 3...
January 15, 2017: Theriogenology
https://www.readbyqxmd.com/read/27754872/expanding-the-role-of-tachykinins-in-the-neuroendocrine-control-of-reproduction
#13
Chrysanthi Fergani, Victor Navarro
Reproductive function is driven by the hormonal interplay between the gonads and brain-pituitary axis. Gonadotropin-releasing hormone (GnRH) is released in a pulsatile manner, which is critical for the attainment and maintenance of fertility, however, GnRH neurons lack the ability to directly respond to most regulatory factors, and a hierarchical upstream neuronal network governs its secretion. We and others proposed a model in which Kiss1 neurons in the arcuate nucleus (ARC), so called KNDy neurons, release kisspeptin (a potent GnRH secretagogue) in a pulsatile manner to drive GnRH pulses under the coordinated autosynaptic action of its cotransmitters, the tachykinin neurokinin B (NKB, stimulatory) and dynorphin (inhibitory)...
October 17, 2016: Reproduction: the Official Journal of the Society for the Study of Fertility
https://www.readbyqxmd.com/read/27715255/pulse-and-surge-profiles-of-luteinizing-hormone-secretion-in-the-mouse
#14
Katja Czieselsky, Mel Prescott, Robert Porteous, Pauline Campos, Jenny Clarkson, Frederik J Steyn, Rebecca E Campbell, Allan E Herbison
Using a new tail-tip bleeding procedure and a sensitive ELISA, we describe here the patterns of LH secretion throughout the mouse estrous cycle; in ovariectomized mice; in ovariectomized, estradiol-treated mice that model estrogen-negative and -positive feedback; and in transgenic GNR23 mice that exhibit allele-dependent reductions in GnRH neuron number. Pulsatile LH secretion was evident at all stages of the estrous cycle, with LH pulse frequency being approximately one pulse per hour in metestrous, diestrous, and proestrous mice but much less frequent at estrus (less than one pulse per 4 h)...
December 2016: Endocrinology
https://www.readbyqxmd.com/read/27701044/corticotropin-releasing-hormone-induces-depression-like-changes-of-sleep-electroencephalogram-in-healthy-women
#15
P Schüssler, M Kluge, W Gamringer, T C Wetter, A Yassouridis, M Uhr, R Rupprecht, A Steiger
We reported previously that repetitive intravenous injections of corticotropin-releasing hormone (CRH) around sleep onset prompt depression-like changes in certain sleep and endocrine activity parameters (e.g. decrease of slow-wave sleep during the second half of the night, blunted growth hormone peak, elevated cortisol concentration during the first half of the night). Furthermore a sexual dimorphism of the sleep-endocrine effects of the hormones growth hormone-releasing hormone and ghrelin was observed. In the present placebo-controlled study we investigated the effect of pulsatile administration of 4×50μg CRH on sleep electroencephalogram (EEG) and nocturnal cortisol and GH concentration in young healthy women...
December 2016: Psychoneuroendocrinology
https://www.readbyqxmd.com/read/27630616/a-timed-kiss-is-essential-for-reproduction-lessons-from-mammalian-studies
#16
REVIEW
Manish Putteeraj, Tomoko Soga, Takayoshi Ubuka, Ishwar S Parhar
Reproduction is associated with the circadian system, primarily as a result of the connectivity between the biological clock in the suprachiasmatic nucleus (SCN) and reproduction-regulating brain regions, such as preoptic area (POA), anteroventral periventricular nucleus (AVPV), and arcuate nucleus (ARC). Networking of the central pacemaker to these hypothalamic brain regions is partly represented by close fiber appositions to specialized neurons, such as kisspeptin and gonadotropin-releasing hormone (GnRH) neurons; accounting for rhythmic release of gonadotropins and sex steroids...
2016: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/27544781/mathematical-modeling-of-gonadotropin-releasing-hormone-signaling
#17
Amitesh Pratap, Kathryn L Garner, Margaritis Voliotis, Krasimira Tsaneva-Atanasova, Craig A McArdle
Gonadotropin-releasing hormone (GnRH) acts via G-protein coupled receptors on pituitary gonadotropes to control of reproduction. These are Gq-coupled receptors that mediate acute effects of GnRH on the exocytotic secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), as well as the chronic regulation of their synthesis. GnRH is secreted in short pulses and GnRH effects on its target cells are dependent upon the dynamics of these pulses. Here we overview GnRH receptors and their signaling network, placing emphasis on pulsatile signaling, and how mechanistic mathematical models and an information theoretic approach have helped further this field...
August 17, 2016: Molecular and Cellular Endocrinology
https://www.readbyqxmd.com/read/27544332/mutations-in-gonadotropin-releasing-hormone-signaling-pathway-in-two-nihh-patients-with-successful-pregnancy-outcomes
#18
Nikolay Zernov, Mikhail Skoblov, Ancha Baranova, Konstantin Boyarsky
BACKGROUND: Anomalous levels of gonadotropin-releasing hormone (GnRH) secretion result in a variety of reproductive phenotypes associated with infertility or subfertility. The normosmic isolated hypogonadotropic hypogonadism (nIHH) is due to a failure of either GnRH pulsatile secretion in hypothalamus or its reception in pituitary. The spectrum of nIHH-associated alterations continues to expand, especially when additional ethnic populations are investigated. The aim of this study was to uncover genetic causes for nIHH in patients of Russian origin...
August 20, 2016: Reproductive Biology and Endocrinology: RB&E
https://www.readbyqxmd.com/read/27512013/phenotypic-spectrum-of-polr3b-mutations-isolated-hypogonadotropic-hypogonadism-without-neurological-or-dental-anomalies
#19
Mary R Richards, Lacey Plummer, Yee-Ming Chan, Margaret F Lippincott, Richard Quinton, Philip Kumanov, Stephanie B Seminara
BACKGROUND: A constellation of neurodegenerative disorders exists (Gordon Holmes syndrome, 4H leucodystrophy, Boucher-Neuhauser syndrome) in which patients suffer from both neurological disease (typically manifested by ataxia) and reproductive failure (idiopathic hypogonadotropic hypogonadism (IHH)). POLR3B, which encodes the second largest subunit of RNA polymerase III (pol III), and POLR3A, which forms the pol III catalytic centre, are associated with 4H leucodystrophy. METHODS: Whole exome sequencing was performed on a large cohort of subjects with IHH (n=565)...
January 2017: Journal of Medical Genetics
https://www.readbyqxmd.com/read/27466366/characterization-of-gonadotrope-secretoproteome-identifies-neurosecretory-protein-vgf-derived-peptide-suppression-of-follicle-stimulating-hormone-gene-expression
#20
Soon Gang Choi, Qian Wang, Jingjing Jia, Maria Chikina, Hanna Pincas, Georgia Dolios, Kazuki Sasaki, Rong Wang, Naoto Minamino, Stephen R J Salton, Stuart C Sealfon
Reproductive function is controlled by the pulsatile release of hypothalamic gonadotropin-releasing hormone (GnRH), which regulates the expression of the gonadotropins luteinizing hormone and FSH in pituitary gonadotropes. Paradoxically, Fshb gene expression is maximally induced at lower frequency GnRH pulses, which provide a very low average concentration of GnRH stimulation. We studied the role of secreted factors in modulating gonadotropin gene expression. Inhibition of secretion specifically disrupted gonadotropin subunit gene regulation but left early gene induction intact...
September 30, 2016: Journal of Biological Chemistry
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