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rhythmic hormone secretion

K Stebelova, J Kosnacova, M Zeman
OBJECTIVE: Melatonin is a hormone predominantly synthesized and secreted during the night by the pineal gland. Artificial light at night, especially its blue part, acutely suppresses the melatonin production. Th e aim of the present study was to find out, whether an intense blue light phototherapy of severe hyperbilirubinemia, may suppress the melatonin production during the night when the eyes will be properly protected by a sleep mask. METHODS: The main melatonin metabolite, 6-sulphatoxymelatonin was measured in urine in a nine-year old boy suffering from the Crigler-Najjar syndrome type I...
January 1, 2017: Endocrine Regulations
Jacques Dayan, Géraldine Rauchs, Bérengère Guillery-Girard
Post-traumatic stress disorder (PTSD) is a complex syndrome that may occur after exposure to one or more traumatic events. It associates physiological, emotional, and cognitive changes Brain and hormonal modifications contribute to some impairments in learning, memory, and emotion regulation. Some of these biological dysfunctions may be analyzed in terms of rhythms dysregulation that would be expressed through endocrine rhythmicity, sleep organization, and temporal synchrony in brain activity. In the first part of this article, we report studies on endocrine rhythmicity revealing that some rhythms abnormalities are frequently observed, although not constantly, for both cortisol and sympathetic nervous system (SNS) activity...
February 1, 2017: Journal of Physiology, Paris
David J Lyons, Arash Hellysaz, Rachida Ammari, Christian Broberger
Hypocretin/Orexin (H/O) neurons of the lateral hypothalamus are compelling modulator candidates for the chronobiology of neuroendocrine output and, as a consequence, hormone release from the anterior pituitary. Here we investigate the effects of H/O peptides upon tuberoinfundibular dopamine (TIDA) neurons - cells which control, via inhibition, the pituitary secretion of prolactin. In whole cell recordings performed in male rat hypothalamic slices, application of H/O-A, as well as H/O-B, excited oscillating TIDA neurons, inducing a reversible depolarising switch from phasic to tonic discharge...
February 1, 2017: Scientific Reports
Aleksandar Z Baburski, Srdjan J Sokanovic, Silvana A Andric, Tatjana S Kostic
The Leydig cell physiology displays a circadian rhythm driven by a complex interaction of the reproductive axis hormones and circadian system. The final output of this regulatory process is circadian pattern of steroidogenic genes expression and testosterone production. Aging gradually decreases robustness of rhythmic testosterone secretion without change in pattern of LH secretion. Here, we analyzed effect of aging on circadian variation of cAMP and cGMP signaling in Leydig cells. Results showed opposite effect of aging on cAMP and cGMP daily variation...
December 3, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
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
Mary S Matsui, Edward Pelle, Kelly Dong, Nadine Pernodet
Circadian rhythms, ≈24 h oscillations in behavior and physiology, are reflected in all cells of the body and function to optimize cellular functions and meet environmental challenges associated with the solar day. This multi-oscillatory network is entrained by the master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, which directs an organism's rhythmic expression of physiological functions and behavior via a hierarchical system. This system has been highly conserved throughout evolution and uses transcriptional-translational autoregulatory loops...
May 24, 2016: International Journal of Molecular Sciences
A P Herman, J Bochenek, K Król, A Krawczyńska, H Antushevich, B Pawlina, A Herman, K Romanowicz, D Tomaszewska-Zaremba
In vertebrates, numerous processes occur in a rhythmic manner. The hormonal signal reliably reflecting the environmental light conditions is melatonin. Nocturnal melatonin secretion patterns could be disturbed in pathophysiological states, including inflammation, Alzheimer's disease, and depression. All of these states share common elements in their aetiology, including the overexpression of interleukin- (IL-) 1β in the central nervous system. Therefore, the present study was designed to determine the effect of the central injection of exogenous IL-1β on melatonin release and on the expression of the enzymes of the melatonin biosynthetic pathway in the pineal gland of ewe...
2016: Mediators of Inflammation
Patricia L Brubaker, Manuel Gil-Lozano
Circadian expression of clock genes in peripheral tissues is critical to the coordinated regulation of intestinal digestive and absorptive functions, insulin secretion, and peripheral tissue nutrient deposition during periods of nutrient ingestion, thereby preventing metabolic dysregulation. As glucagon-like peptide-1 is a key incretin hormone that regulates glucose-dependent insulin secretion, we hypothesized that this intestinal hormone is a player in the peripheral metabolic clock, linking nutrient ingestion to insulin secretion...
April 2016: Journal of Diabetes Investigation
Philipp Schwabl, Elisa Bonaccorso, Wolfgang Goymann
BACKGROUND: Glucocorticoids are adrenal steroid hormones essential to homeostatic maintenance. Their daily variation at low concentrations regulates physiology and behavior to sustain proper immunological and metabolic function. Glucocorticoids rise well above these baseline levels during stress to elicit emergency-state responses that increase short-term survival. Despite this essence in managing life processes under both regular and adverse conditions, relationships of glucocorticoid release to environmental and intrinsic factors that vary at daily and seasonal scales are rarely studied in the wild...
2016: Frontiers in Zoology
Hana Vakili, Yan Jin, Peter A Cattini
Rhythmicity of biological functions is fundamental for optimal adaptations to environmental cues. Growth hormone (GH) is a major metabolic homeostatic factor that is secreted with a circadian pattern, but whether it is synthesized rhythmically is unknown. We used transgenic mice containing the human (h) GH gene (hGH1) locus to investigate the rhythmicity of hGH synthesis and secretion and to show that RNA and secreted protein levels oscillate over a 24-h cycle. Analysis of hGH1 promoter sequences revealed an enhancer motif (E-box) element that binds the circadian transcriptional machinery (Bmal1 and Clock)...
June 24, 2016: Journal of Biological Chemistry
Dorela D Shuboni, Amna A Agha, Thomas K H Groves, Andrew J Gall
Melatonin is a hormone rhythmically secreted at night by the pineal gland in vertebrates. In diurnal mammals, melatonin is present during the inactive phase of the rest/activity cycle, and in primates it directly facilitates sleep and decreases body temperature. However, the role of the pineal gland for the promotion of sleep at night has not yet been studied in non-primate diurnal mammalian species. Here, the authors directly examined the hypothesis that the pineal gland contributes to diurnality in Nile grass rats by decreasing activity and increasing sleep at night, and that this could occur via effects on circadian mechanisms or masking, or both...
July 2016: Behavioural Processes
Manuel Gil-Lozano, W Kelly Wu, Alexandre Martchenko, Patricia L Brubaker
Secretion of the incretin hormone, glucagon-like peptide-1 (GLP-1), by the intestinal L-cell is rhythmically regulated by an independent molecular clock. However, the impact of factors known to affect the activity of similar cell-autonomous clocks, such as circulating glucocorticoids and high-fat feeding, on GLP-1 secretory patterns remains to be elucidated. Herein the role of the endogenous corticosterone rhythm on the pattern of GLP-1 and insulin nutrient-induced responses was examined in corticosterone pellet-implanted rats...
February 2016: Endocrinology
Yoshiaki Yamaguchi
The endogenous circadian clock drives robust oscillations in physiology and behavior, such as hormone secretions and sleep/wake cycles, with a period of about 24 h. We are rarely aware of this internal clock system because it is usually synchronized with environmental light-dark cycles. However, travelling rapidly across multiple time zones in a jet airplane suddenly makes us aware of the desynchrony between the body clock and external time, causing sleep disturbances and gastrointestinal problems. Although jet lag is recognized as a chronobiological problem, its specific molecular and neural mechanisms are poorly understood...
2015: Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
Partha Pratim Nath, Kaushik Sarkar, Mukti Mondal, Goutam Paul
Metanil yellow (MY) is a most frequently used food color in West Bengal, India. The toxic effects of MY on the male reproductive system have been reported discriminately in animal models. The probable toxic effects of MY on female reproductive functions have not been reported till date. Therefore, this study was designed to examine the effect of MY on estrous cycle rhythmicity and ovarian folliculogenesis in female rats. Rats have been exposed to MY at three doses of 250, 500, 750 mg kgBW(-1)  day(-1) for two exposure durations, 20 and 30 days...
October 23, 2015: Environmental Toxicology
Fang Bai, Chae Ho Lim, Jingyue Jia, Katherine Santostefano, Chelsey Simmons, Hideko Kasahara, Weihui Wu, Naohiro Terada, Shouguang Jin
Forced expression of defined transcriptional factors has been well documented as an effective method for cellular reprogramming or directed differentiation. However, transgene expression is not amenable for therapeutic application due to potential insertional mutagenesis. Here, we have developed a bacterial type III secretion system (T3SS)-based protein delivery tool and shown its application in directing pluripotent stem cell differentiation by a controlled delivery of transcription factors relevant to early heart development...
2015: Scientific Reports
Sjoerd D Joustra, Ferdinand Roelfsema, Erik Endert, Bart E P B Ballieux, A S Paul van Trotsenburg, Eric Fliers, Eleonora P M Corssmit, Daniel J Bernard, Wilma Oostdijk, Jan Maarten Wit, Alberto M Pereira, Nienke R Biermasz
BACKGROUND: Loss-of-function mutations in immunoglobulin superfamily member 1 (IGSF1) cause an X-linked syndrome of central hypothyroidism, macroorchidism, delayed pubertal testosterone rise, variable prolactin deficiency and variable partial GH deficiency in childhood. The clinical features and gene expression pattern suggest a pivotal role for IGSF1 in the pituitary, but detailed knowledge on pituitary hormone secretion in this syndrome is lacking. We therefore aimed to study the 24-hour pituitary hormone secretion in male patients with IGSF1 deficiency...
2016: Neuroendocrinology
Kristin Eckel-Mahan, Paolo Sassone-Corsi
Circadian rhythms take place with a periodicity of 24 hr, temporally following the rotation of the earth around its axis. Examples of circadian rhythms are the sleep/wake cycle, feeding, and hormone secretion. Light powerfully entrains the mammalian clock and assists in keeping animals synchronized to the 24-hour cycle of the earth by activating specific neurons in the "central pacemaker" of the brain, the suprachiasmatic nucleus. Absolute periodicity of an animal can deviate slightly from 24 hr as manifest when an animal is placed into constant dark or "free-running" conditions...
2015: Current Protocols in Mouse Biology
Steffy W Jansen, Ferdinand Roelfsema, Evie van der Spoel, Abimbola A Akintola, Iris Postmus, Bart E Ballieux, P Eline Slagboom, Christa M Cobbaert, Jeroen van der Grond, Rudi G Westendorp, Hanno Pijl, Diana van Heemst
CONTEXT: Longevity is associated with changes in circulating levels of thyroid hormone (TH) and/or TSH in animals and humans, but underlying mechanisms remain elusive. OBJECTIVE: We explored in 38 offspring of nonagenarian participants from the Leiden Longevity Study, who are enriched for longevity and in their partners, ultradian and circadian rhythmicity of TSH, temporal relationship, and feedback and forward interplay between TSH and TH. METHODS: We collected blood samples every 10 minutes for 24 hours for TSH and TH profiles...
October 2015: Journal of Clinical Endocrinology and Metabolism
Ibtissam Chakir, Stéphanie Dumont, Paul Pévet, Ali Ouarour, Etienne Challet, Patrick Vuillez
Nocturnal secretion of melatonin from the pineal gland may affect central and peripheral timing, in addition to its well-known involvement in the control of seasonal physiology. The Syrian hamster is a photoperiodic species, which displays gonadal atrophy and increased adiposity when adapted to short (winter-like) photoperiods. Here we investigated whether pineal melatonin secreted at night can impact daily rhythmicity of metabolic hormones and glucose in that seasonal species. For that purpose, daily variations of plasma leptin, cortisol, insulin and glucose were analyzed in pinealectomized hamsters, as compared to sham-operated controls kept under very long (16 h light/08 h dark) or short photoperiods (08 h light/16 h dark)...
2015: Frontiers in Neuroscience
Gloria Laryea, Melinda Arnett, Louis J Muglia
Glucocorticoid receptors (GR) in the paraventricular nucleus of the hypothalamus (PVN) are important regulators of negative feedback regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Previous evaluation of endogenous PVN GR function in adult mice demonstrated that mice with loss of GR exon 3 in the PVN (Sim1Cre-GRe3Δ) have a hyperactive HPA axis, growth impairment and metabolic disruptions. Here, we hypothesized that lack of negative feedback inhibition of the HPA axis through PVN GR, as demonstrated through loss of PVN GR early in life, will have developmental-stage-specific consequences...
2015: Stress: the International Journal on the Biology of Stress
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