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https://www.readbyqxmd.com/read/29208686/effects-of-growth-hormone-administration-on-luteinizing-hormone-secretion-in-healthy-older-men-and-women
#1
Ranganath Muniyappa, Shannon D Sullivan, Sri Harsha Tella, Brent S Abel, S Mitchell Harman, Marc R Blackman
The known interactions between the somatotropic and hypothalamic-pituitary-gonadal (HPG) axes have not been well delineated in older individuals. Aging-associated decline in insulin like growth factor-1 (IGF-1) levels has been proposed to play a role in reproductive senescence in animals. However, the effects of GH on LH secretion are unknown in older individuals. Our objective was to determine whether GH modulates LH secretion or levels of sex steroids (SS) in healthy older (ages 65-88 years) men (n = 24) and women (n = 24) with low-normal plasma IGF-1 levels...
December 2017: Physiological Reports
https://www.readbyqxmd.com/read/29203206/expression-of-hypothalamic-kisspeptin-neurokinin-b-and-dynorphin-a-neurons-attenuates-in-female-zucker-fatty-rats
#2
Kimihiko Nakao, Kinuyo Iwata, Toshiyuki Takeshita, Hitoshi Ozawa
Zucker fatty (ZF) rats are considered to be an obese model due to leptin receptor abnormality and such rats show infertility. Pulsatile gonadotropin-releasing hormone/luteinizing hormone (LH) secretion, which is important for follicular development in females, is considered to be controlled by KNDy neurons coexpressing kisspeptin, neurokinin B (NKB), and dynorphin A (DynA), encoded by Kiss1, Tac3, and Pdyn, respectively, in the hypothalamic arcuate nucleus (ARC). The purpose of this study is to examine the expression of KNDy neurons in female ZF rats by histochemical approach because pulsatile LH secretion is suppressed...
December 1, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/29203140/coordination-or-coincidence-the-relationship-between-prolactin-and-gonadotropin-secretion
#3
David R Grattan
A recent paper demonstrates that kisspeptin can stimulate the secretion of both prolactin and luteinizing hormone (LH). This provides novel insight into mechanisms that could account for previous observations of concordant patterns of secretion of the two hormones, such as pulsatile secretion with simultaneous pulses, as well as the preovulatory surges of both prolactin and LH.
December 1, 2017: Trends in Endocrinology and Metabolism: TEM
https://www.readbyqxmd.com/read/29171353/the-neuro-control-of-the-ovarain-cycle-a-hypothesis
#4
Bruno Lunenfeld, Klaus Bühler
Since more than 100 years, it is known that pituitary function depends upon the function of higher centers in the brain. It was already assumed at this time that pituitary extracts could influence the gonads and postulated that their use could have practical applications. In 1926, the 'gonadal principle' was discovered revealing the regulation of ovarian function by the pituitary. The two pituitary hormones were called 'Prolan A' and 'Prolan B' which are responsible for ovarian function especially secretion of the hormones: 'lutein' and 'foliculin'...
November 24, 2017: Gynecological Endocrinology
https://www.readbyqxmd.com/read/29163358/reactive-oxygen-species-link-gonadotropin-releasing-hormone-receptor-signaling-cascades-in-the-gonadotrope
#5
Tomohiro Terasaka, Mary E Adakama, Song Li, Taeshin Kim, Eri Terasaka, Danmei Li, Mark A Lawson
Biological rhythms lie at the center of regulatory schemes that control many aspects of living systems. At the cellular level, meaningful responses to external stimuli depend on propagation and quenching of a signal to maintain vigilance for subsequent stimulation or changes that serve to shape and modulate the response. The hypothalamus-pituitary-gonad endocrine axis that controls reproductive development and function relies on control through rhythmic stimulation. Central to this axis is the pulsatile stimulation of the gonadotropes by hypothalamic neurons through episodic release of the neuropeptide gonadotropin-releasing hormone...
2017: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/29136398/molecular-cloning-and-epigenetic-change-detection-of-kiss1-during-seasonal-reproduction-in-chinese-indigenous-sheep
#6
Xiaoyun He, Qiuyue Liu, Xiaoyu Li, Xiaofei Guo, Xiangyu Wang, Wenping Hu, Ran Di, Mingxing Chu
Like most seasonal domesticated species, sheep are short-day breeders, which means that the reproduction axis is activated by short days. The annual photoperiodic cycle affects the amount of daylength information that is transmitted to the hypothalamic-pituitary-gonadal (HPG) axis by regulating pulsatile secretion of gonadotrophin-releasing hormone from the hypothalamus. Kisspeptin, which is encoded by Kiss1, plays a major role in reproductive seasonality. Based on results from our previous Solexa sequencing data obtained from Tan (T) and Small Tail Han (STH) sheep during anoestrus and the breeding season, full-length mRNA information for ovine Kiss1 was obtained; 894bp in T sheep and 1145bp in STH sheep...
November 15, 2017: Reproduction, Fertility, and Development
https://www.readbyqxmd.com/read/29126131/continuous-kisspeptin-restores-luteinizing-hormone-pulsatility-following-cessation-by-a-neurokinin-b-antagonist-in-female-sheep
#7
Iain J Clarke, Qun Li, Belinda A Henry, Robert P Millar
Pulsatile secretion of gonadotropin releasing hormone (GnRH) drives pulsatile secretion of luteinizing hormone (LH), with evidence that this depends upon kisspeptin (Kiss) input to GnRH neurons. Kiss administration causes acute GnRH/LH secretion and electrophysiological data suggest that Kiss neurons may act in a phasic manner to drive GnRH secretion, but there is not definitive evidence for this. The product of the Kiss1 gene is proteolytically cleaved to smaller products and the 10 amino-acid C-terminal product (Kiss-10) displays full bioactivity...
November 3, 2017: Endocrinology
https://www.readbyqxmd.com/read/29109258/definition-of-the-hypothalamic-gnrh-pulse-generator-in-mice
#8
Jenny Clarkson, Su Young Han, Richard Piet, Timothy McLennan, Grace M Kane, Jamie Ng, Robert W Porteous, Joon S Kim, William H Colledge, Karl J Iremonger, Allan E Herbison
The pulsatile release of luteinizing hormone (LH) is critical for mammalian fertility. However, despite several decades of investigation, the identity of the neuronal network generating pulsatile reproductive hormone secretion remains unproven. We use here a variety of optogenetic approaches in freely behaving mice to evaluate the role of the arcuate nucleus kisspeptin (ARNKISS) neurons in LH pulse generation. Using GCaMP6 fiber photometry, we find that the ARNKISS neuron population exhibits brief (∼1 min) synchronized episodes of calcium activity occurring as frequently as every 9 min in gonadectomized mice...
November 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29102564/gonadotropin-regulation-by-pulsatile-gnrh-signaling-and-gene-expression
#9
REVIEW
George A Stamatiades, Ursula B Kaiser
The precise orchestration of hormonal regulation at all levels of the hypothalamic-pituitary-gonadal axis is essential for normal reproductive function and fertility. The pulsatile secretion of hypothalamic gonadotropin-releasing hormone (GnRH) stimulates the synthesis and release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by pituitary gonadotropes. GnRH acts by binding to its high affinity seven-transmembrane receptor (GnRHR) on the cell surface of anterior pituitary gonadotropes. Different signaling cascades and transcriptional mechanisms are activated, depending on the variation in GnRH pulse frequency, to stimulate the synthesis and release of FSH and LH...
November 2, 2017: Molecular and Cellular Endocrinology
https://www.readbyqxmd.com/read/29092409/dissipative-structures-and-biological-rhythms
#10
Albert Goldbeter
Sustained oscillations abound in biological systems. They occur at all levels of biological organization over a wide range of periods, from a fraction of a second to years, and with a variety of underlying mechanisms. They control major physiological functions, and their dysfunction is associated with a variety of physiological disorders. The goal of this review is (i) to give an overview of the main rhythms observed at the cellular and supracellular levels, (ii) to briefly describe how the study of biological rhythms unfolded in the course of time, in parallel with studies on chemical oscillations, (iii) to present the major roles of biological rhythms in the control of physiological functions, and (iv) the pathologies associated with the alteration, disappearance, or spurious occurrence of biological rhythms...
October 2017: Chaos
https://www.readbyqxmd.com/read/29035710/blunted-basal-corticosterone-pulsatility-predicts-post-exposure-susceptibility-to-ptsd-phenotype-in-rats
#11
Dor Danan, Michael A Matar, Zeev Kaplan, Joseph Zohar, Hagit Cohen
The basal activity of the hypothalamic-pituitary-adrenal axis is highly dynamic and is characterized by both circadian and ultradian (pulsatile) patterns of hormone secretion. Pulsatility of glucocorticoids has been determined to be critical for optimal transcriptional, neuroendocrine, and behavioral responses. We used an animal model of post-traumatic stress disorder (PTSD) to assess whether stress-induced impairment of behavioral responses is correlated with aberrant secretion of corticosterone. Serial blood samples were collected manually via the jugular vein cannula during the light-(inactive)-phase in conscious male rats at 20-min intervals for a period of 5h before and 6...
October 7, 2017: Psychoneuroendocrinology
https://www.readbyqxmd.com/read/28973125/acute-psychosocial-stress-inhibits-lh-pulsatility-and-kiss1-neuronal-activation-in-female-mice
#12
Jennifer A Yang, Christopher I Song, Jessica K Hughes, Michael J Kreisman, Ruby A Parra, Daniel J Haisenleder, Alexander S Kauffman, Kellie M Breen
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...
November 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/28967904/a-growth-hormone-receptor-snp-promotes-lung-cancer-by-impairment-of-socs2-mediated-degradation
#13
Y Chhabra, H Y Wong, L F Nikolajsen, H Steinocher, A Papadopulos, K A Tunny, F A Meunier, A G Smith, B B Kragelund, A J Brooks, M J Waters
Both humans and mice lacking functional growth hormone (GH) receptors are known to be resistant to cancer. Further, autocrine GH has been reported to act as a cancer promoter. Here we present the first example of a variant of the GH receptor (GHR) associated with cancer promotion, in this case lung cancer. We show that the GHRP495T variant located in the receptor intracellular domain is able to prolong the GH signal in vitro using stably expressing mouse pro-B-cell and human lung cell lines. This is relevant because GH secretion is pulsatile, and extending the signal duration makes it resemble autocrine GH action...
October 2, 2017: Oncogene
https://www.readbyqxmd.com/read/28957852/the-subtyping-of-primary-aldosteronism-by-adrenal-vein-sampling-sequential-blood-sampling-causes-factitious-lateralization
#14
Giacomo Rossitto, Michele Battistel, Giulio Barbiero, Valeria Bisogni, Giuseppe Maiolino, Miotto Diego, Teresa M Seccia, Gian Paolo Rossi
BACKGROUND: The pulsatile secretion of adrenocortical hormones and a stress reaction occurring when starting adrenal vein sampling (AVS) can affect the selectivity and also the assessment of lateralization when sequential blood sampling is used. We therefore tested the hypothesis that a simulated sequential blood sampling could decrease the diagnostic accuracy of lateralization index for identification of aldosterone-producing adenoma (APA), as compared with bilaterally simultaneous AVS...
September 27, 2017: Journal of Hypertension
https://www.readbyqxmd.com/read/28938486/the-two-populations-of-kisspeptin-neurons-are-involved-in-the-ram-induced-lh-pulsatile-secretion-and-lh-surge-in-anestrous-ewes
#15
Claude Fabre-Nys, Juliette Cognié, Laurence Dufourny, Meriem Ghenim, Stephanie Martinet, Olivier Lasserre, Didier Lomet, Robert P Millar, Satoshi Ohkura, Yuta Suetomi
Exposure to a ram during spring stimulates luteinizing hormone (LH) secretion and can induce ovulation in sexually quiescent ewes ("ram effect"). Kisspeptin (Kiss) present in the arcuate nucleus (ARC) and the preoptic area (POA) is a potent stimulators of LH secretion. Our aim was to investigate whether Kiss neurons mediate the increase in LH secretion during the ram effect. With double immunofluorescent detection, we identified Kiss neurons (Kiss IR) activated (Fos IR) by exposure to a ram for 2 hours (M2) or 12 hours (M12) or to ewes for 2 hours (C)...
November 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/28903914/long-term-treatment-with-the-ghrelin-receptor-antagonist-d-lys3-ghrp-6-does-not-improve-glucose-homeostasis-in-non-obese-diabetic-mkr-mice
#16
Rasha Mosa, Lili Huang, Hongzhuo Li, Michael Grist, Derek LeRoith, Chen Chen
Ghrelin secretion has been associated with increased caloric intake and adiposity. The expressions of ghrelin and its receptor (GHS-R1a) in pancreas have raised the interest about the role of ghrelin in glucose homeostasis. Most of the studies showed that ghrelin promoted hyperglycaemia and inhibited insulin secretion. This raised the interest in using GHS-R1a antagonists as therapeutic targets for type 2 diabetes. Available data of GHS-R antagonists are on a short-term basis. Moreover, the complexity of GHS-R1a signalling makes it difficult to understand the mechanism of action of GHS-R1a antagonists...
September 13, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28859282/a-neurokinin-3-receptor-selective-agonist-accelerates-pulsatile-luteinizing-hormone-secretion-in-lactating-cattle
#17
Sho Nakamura, Yoshihiro Wakabayashi, Takashi Yamamura, Satoshi Ohkura, Shuichi Matsuyama
Pulsatile gonadotropin-releasing hormone (GnRH) secretion, which is indispensable for follicular development, is suppressed in lactating dairy and beef cattle. Neurokinin B (NKB) neurons in the arcuate nucleus of the hypothalamus are considered to play an essential role in generating the pulsatile mode of GnRH/luteinizing hormone (LH) secretion. The present study aimed to clarify the role of NKB-neurokinin 3 receptor (NK3R) signaling in the pulsatile pattern of GnRH/gonadotropin secretion in postpartum lactating cattle...
July 1, 2017: Biology of Reproduction
https://www.readbyqxmd.com/read/28808344/hypothalamic-effects-of-progesterone-on-regulation-of-the-pulsatile-and-surge-release-of-luteinising-hormone-in-female-rats
#18
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
#19
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
#20
Karolina Skorupskaite, Jyothis T George, Johannes D Veldhuis, Robert P Millar, Richard A Anderson
OBJECTIVE: Patients with mutations of neurokinin B (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 40 mg 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
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