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Goh GH, Maloney SK, Mark PJ, Blache D. Episodic Ultradian Events-Ultradian Rhythms. BIOLOGY 2019; 8:E15. [PMID: 30875767 PMCID: PMC6466064 DOI: 10.3390/biology8010015] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/24/2019] [Accepted: 03/09/2019] [Indexed: 11/16/2022]
Abstract
In the fast lane of chronobiology, ultradian events are short-term rhythms that have been observed since the beginning of modern biology and were quantified about a century ago. They are ubiquitous in all biological systems and found in all organisms, from unicellular organisms to mammals, and from single cells to complex biological functions in multicellular animals. Since these events are aperiodic and last for a few minutes to a few hours, they are better classified as episodic ultradian events (EUEs). Their origin is unclear. However, they could have a molecular basis and could be controlled by hormonal inputs-in vertebrates, they originate from the activity of the central nervous system. EUEs are receiving increasing attention but their aperiodic nature requires specific sampling and analytic tools. While longer scale rhythms are adaptations to predictable changes in the environment, in theory, EUEs could contribute to adaptation by preparing organisms and biological functions for unpredictability.
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Affiliation(s)
- Grace H Goh
- School of Human Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
| | - Shane K Maloney
- School of Human Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
| | - Peter J Mark
- School of Human Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
| | - Dominique Blache
- School of Agriculture and Environment and UWA Institute of Agriculture, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
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He W, Li X, Adekunbi D, Liu Y, Long H, Wang L, Lyu Q, Kuang Y, O'Byrne KT. Hypothalamic effects of progesterone on regulation of the pulsatile and surge release of luteinising hormone in female rats. Sci Rep 2017; 7:8096. [PMID: 28808344 PMCID: PMC5556103 DOI: 10.1038/s41598-017-08805-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/12/2017] [Indexed: 01/10/2023] Open
Abstract
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. This study examined the hypothesis that progesterone inhibits LH surge and pulsatile secretion via its receptor in the ARC and/or AVPV nuclei. Adult female rats received a single injection of pregnant mare serum gonadotropin followed by progesterone or vehicle. Progesterone administration resulted in a significant prolongation of the oestrous cycle and blockade of LH surge. However, microinjection of the progesterone receptor antagonist, RU486, into the AVPV reversed the prolonged cycle length and rescued the progesterone blockade LH surge, while RU486 into the ARC shortened LH pulse interval in the progesterone treated rats. These results demonstrated that progesterone's inhibitory effect on the GnRH/LH surge and pulsatile secretion is mediated by its receptor in the kisspeptin enriched hypothalamic AVPV and ARC respectively, which are essential for progesterone regulation of oestrous cyclicity in rats.
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Affiliation(s)
- Wen He
- Department of Assisted Reproduction, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
| | - Xiaofeng Li
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London, UK
| | - Daniel Adekunbi
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London, UK
| | - Yali Liu
- Department of Assisted Reproduction, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
| | - Hui Long
- Department of Assisted Reproduction, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
| | - Li Wang
- Department of Assisted Reproduction, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
| | - Qifeng Lyu
- Department of Assisted Reproduction, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
| | - Yanping Kuang
- Department of Assisted Reproduction, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China.
| | - Kevin T O'Byrne
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London, UK.
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3
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Li X, Shao B, Lin C, O'Byrne KT, Lin Y. Stress-induced inhibition of LH pulses in female rats: role of GABA in arcuate nucleus. J Mol Endocrinol 2015; 55:9-19. [PMID: 25999179 DOI: 10.1530/jme-15-0084] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/21/2015] [Indexed: 12/21/2022]
Abstract
Stress exerts profound inhibitory effects on reproductive function by suppression of the pulsatile release of GnRH and therefore LH. Besides the corticotrophin-releasing factor (CRF), this effect also might be mediated via GABAergic signaling within the arcuate nucleus (ARC) since its inhibitory effects on LH pulses and increased activity during stress. In the present study, we investigated the role of endogenous GABAergic signaling within the ARC in stress-induced suppression of LH pulses. Ovariectomised oestradiol-replaced rats were implanted with bilateral and unilateral cannulae targeting toward the ARC and lateral cerebral ventricle respectively. Blood samples (25 μl) were taken via chronically implanted cardiac catheters every 5 min for 6 h for measurement of LH pulses. Intra-ARC infusion of GABAA receptor antagonist, bicuculline (0.2 pmol in 200 nl artificial cerebrospinal fluid (aCSF) each side, three times at 20-min intervals) markedly attenuated the inhibitory effect of lipopolysaccharide (LPS; 25 μg/kg i.v.) but not restraint (1 h) stress on pulsatile LH secretion. In contrast, restraint but not LPS stress-induced suppression of LH pulse frequency was reversed by intra-ARC administration of GABABR antagonist, CGP-35348 (1.5 nmol in 200 nl aCSF each side, three times at 20-min intervals). Moreover, intra-ARC application of either bicuculline or CGP-35348 attenuated the inhibitory effect of CRF (1 nmol in 4 μl aCSF, i.c.v.) on the LH pulses. These data indicate a pivotal and differential role of endogenous GABAA and GABAB signaling mechanisms in the ARC with respect to mediating immunological and psychological stress-induced suppression of the GnRH pulse generator respectively.
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Affiliation(s)
- XiaoFeng Li
- First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Bei Shao
- First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - ChengCheng Lin
- First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Kevin T O'Byrne
- First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - YuanShao Lin
- First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China First Department of NeurologyFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, ChinaDivision of Women's HealthSchool of Medicine, King's College London, Guy's Campus, London, UKDepartment of Surgery LaboratoryFirst Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
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4
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Hu MH, Li XF, McCausland B, Li SY, Gresham R, Kinsey-Jones JS, Gardiner JV, Sam AH, Bloom SR, Poston L, Lightman SL, Murphy KG, O'Byrne KT. Relative Importance of the Arcuate and Anteroventral Periventricular Kisspeptin Neurons in Control of Puberty and Reproductive Function in Female Rats. Endocrinology 2015; 156:2619-31. [PMID: 25875299 PMCID: PMC4475719 DOI: 10.1210/en.2014-1655] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Kisspeptin plays a critical role in pubertal timing and reproductive function. In rodents, kisspeptin perikarya within the hypothalamic arcuate (ARC) and anteroventral periventricular (AVPV) nuclei are thought to be involved in LH pulse and surge generation, respectively. Using bilateral microinjections of recombinant adeno-associated virus encoding kisspeptin antisense into the ARC or AVPV of female rats at postnatal day 10, we investigated the relative importance of these two kisspeptin populations in the control of pubertal timing, estrous cyclicity, and LH surge and pulse generation. A 37% knockdown of kisspeptin in the AVPV resulted in a significant delay in vaginal opening and first vaginal estrous, abnormal estrous cyclicity, and reduction in the occurrence of spontaneous LH surges, although these retained normal amplitude. This AVPV knockdown had no effect on LH pulse frequency, measured after ovariectomy. A 32% reduction of kisspeptin in the ARC had no effect on the onset of puberty but resulted in abnormal estrous cyclicity and decreased LH pulse frequency. Additionally, the knockdown of kisspeptin in the ARC decreased the amplitude but not the incidence of LH surges. These results might suggest that the role of AVPV kisspeptin in the control of pubertal timing is particularly sensitive to perturbation. In accordance with our previous studies, ARC kisspeptin signaling was critical for normal pulsatile LH secretion in female rats. Despite the widely reported role of AVPV kisspeptin neurons in LH surge generation, this study suggests that both AVPV and ARC populations are essential for normal LH surges and estrous cyclicity.
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Affiliation(s)
- M H Hu
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - X F Li
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - B McCausland
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - S Y Li
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - R Gresham
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - J S Kinsey-Jones
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - J V Gardiner
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - A H Sam
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - S R Bloom
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - L Poston
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - S L Lightman
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - K G Murphy
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
| | - K T O'Byrne
- Division of Women's Health (M.H.H., X.F.L., B.M., S.Y.L., R.G., L.P., K.T.O.), Faculty of Life Sciences and Medicine, King's College London, Guy's Campus, London SE1 1UL, United Kingdom; Section of Investigative Medicine (J.S.K.-J., J.V.G., A.H.S., S.R.B., K.G.M.), Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, London W12 0NN, United Kingdom; and Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology (S.L.L.), University of Bristol, Bristol BS13NY, United Kingdom
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5
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Comninos AN, Anastasovska J, Sahuri-Arisoylu M, Li X, Li S, Hu M, Jayasena CN, Ghatei MA, Bloom SR, Matthews PM, O'Byrne KT, Bell JD, Dhillo WS. Kisspeptin signaling in the amygdala modulates reproductive hormone secretion. Brain Struct Funct 2015; 221:2035-47. [PMID: 25758403 PMCID: PMC4853463 DOI: 10.1007/s00429-015-1024-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/02/2015] [Indexed: 12/27/2022]
Abstract
Kisspeptin (encoded by KISS1) is a crucial activator of reproductive function. The role of kisspeptin has been studied extensively within the hypothalamus but little is known about its significance in other areas of the brain. KISS1 and its cognate receptor are expressed in the amygdala, a key limbic brain structure with inhibitory projections to hypothalamic centers involved in gonadotropin secretion. We therefore hypothesized that kisspeptin has effects on neuronal activation and reproductive pathways beyond the hypothalamus and particularly within the amygdala. To test this, we mapped brain neuronal activity (using manganese-enhanced MRI) associated with peripheral kisspeptin administration in rodents. We also investigated functional relevance by measuring the gonadotropin response to direct intra-medial amygdala (MeA) administration of kisspeptin and kisspeptin antagonist. Peripheral kisspeptin administration resulted in a marked decrease in signal intensity in the amygdala compared to vehicle alone. This was associated with an increase in luteinizing hormone (LH) secretion. In addition, intra-MeA administration of kisspeptin resulted in increased LH secretion, while blocking endogenous kisspeptin signaling within the amygdala by administering intra-MeA kisspeptin antagonist decreased both LH secretion and LH pulse frequency. We provide evidence for the first time that neuronal activity within the amygdala is decreased by peripheral kisspeptin administration and that kisspeptin signaling within the amygdala contributes to the modulation of gonadotropin release and pulsatility. Our data suggest that kisspeptin is a 'master regulator' of reproductive physiology, integrating limbic circuits with the regulation of gonadotropin-releasing hormone neurons and reproductive hormone secretion.
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Affiliation(s)
- Alexander N Comninos
- Department of Investigative Medicine, Imperial College London, 6th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Jelena Anastasovska
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Meliz Sahuri-Arisoylu
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Xiaofeng Li
- Division of Women's Health, School of Medicine, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Shengyun Li
- Division of Women's Health, School of Medicine, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Minghan Hu
- Division of Women's Health, School of Medicine, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Channa N Jayasena
- Department of Investigative Medicine, Imperial College London, 6th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Mohammad A Ghatei
- Department of Investigative Medicine, Imperial College London, 6th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Stephen R Bloom
- Department of Investigative Medicine, Imperial College London, 6th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Paul M Matthews
- Division of Brain Sciences, Imperial College London, Hammersmith Hospital, London, W12 0NN, UK
| | - Kevin T O'Byrne
- Division of Women's Health, School of Medicine, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Jimmy D Bell
- Metabolic and Molecular Imaging Group, MRC Clinical Science Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Waljit S Dhillo
- Department of Investigative Medicine, Imperial College London, 6th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
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6
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Roelfsema F, Pereira AM, Veldhuis JD. Impact of Adiposity and Fat Distribution on the Dynamics of Adrenocorticotropin and Cortisol Rhythms. Curr Obes Rep 2014; 3:387-95. [PMID: 26626915 DOI: 10.1007/s13679-014-0118-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Obesity impacts many hormonal systems, including pituitary hormones, as well as insulin and leptin. In this review we discuss articles which investigate the influence of obesity on the hypothalamic-pituitary-adrenal (HPA) axis. Different techniques have been used to assess the function of the HPA-axis in obesity, including measuring fasting and/or late evening levels of adrenocorticotropic hormone (ACTH) and (free) cortisol in plasma and saliva, studying feedback with dexamethasone or cortisol, and evaluating responsiveness of the system to corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) or ACTH 1-29. In addition, more elaborate studies investigated 24-h secretion patterns, analyzed with deconvolution techniques to quantitate pulsatile secretion rates of cortisol and less often ACTH. Other investigators used timed infusions of labeled cortisol for the estimation of the 24-h secretion rate, clearance rate and distribution volume. Many studies relied on the 24-h urinary excretion of free cortisol, but for quantitation of the 24-h secretion, measurement of all cortisol-derived metabolites is required. Several studies have applied modern liquid chromatography-tandem-mass spectrometry techniques to measure these metabolites. The picture emerging from all these studies is that, first, ACTH secretion is amplified, likely via enhanced forward drive; and, second, serum cortisol levels are normal or even low, associated with a normal 24-h cortisol secretion per liter distribution volume determined by deconvolution, but enhanced when based on the increased total distribution volume associated with obesity. Increased cortisol secretion was also established by isotope dilution studies and reports based on the measurement of all urinary cortisol metabolites. The responsiveness of the adrenal gland to ACTH is diminished. The studies do not address quantitative aspects of cortisol-cortisone metabolism on individual organs, including liver, central and peripheral fat, intestine, skin, and muscle.
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Affiliation(s)
- Ferdinand Roelfsema
- Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Albinusdreef 2, 2333ZA, Leiden, The Netherlands.
| | - Alberto M Pereira
- Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Albinusdreef 2, 2333ZA, Leiden, The Netherlands
| | - Johannes D Veldhuis
- Endocrine Research Unit, Mayo Medical and Graduate Schools, Clinical Translational Research Center, Mayo Clinic, Rochester, MN, 55901, USA
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7
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Mourão M, Satin L, Schnell S. Optimal experimental design to estimate statistically significant periods of oscillations in time course data. PLoS One 2014; 9:e93826. [PMID: 24699692 PMCID: PMC3974819 DOI: 10.1371/journal.pone.0093826] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 03/07/2014] [Indexed: 12/04/2022] Open
Abstract
We investigated commonly used methods (Autocorrelation, Enright, and Discrete Fourier Transform) to estimate the periodicity of oscillatory data and determine which method most accurately estimated periods while being least vulnerable to the presence of noise. Both simulated and experimental data were used in the analysis performed. We determined the significance of calculated periods by applying these methods to several random permutations of the data and then calculating the probability of obtaining the period's peak in the corresponding periodograms. Our analysis suggests that the Enright method is the most accurate for estimating the period of oscillatory data. We further show that to accurately estimate the period of oscillatory data, it is necessary that at least five cycles of data are sampled, using at least four data points per cycle. These results suggest that the Enright method should be more widely applied in order to improve the analysis of oscillatory data.
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Affiliation(s)
- Márcio Mourão
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Leslie Satin
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Santiago Schnell
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department for Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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8
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Beale KE, Kinsey-Jones JS, Gardiner JV, Harrison EK, Thompson EL, Hu MH, Sleeth ML, Sam AH, Greenwood HC, McGavigan AK, Dhillo WS, Mora JM, Li XF, Franks S, Bloom SR, O'Byrne KT, Murphy KG. The physiological role of arcuate kisspeptin neurons in the control of reproductive function in female rats. Endocrinology 2014; 155:1091-8. [PMID: 24424033 PMCID: PMC3929743 DOI: 10.1210/en.2013-1544] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Kisspeptin plays a pivotal role in pubertal onset and reproductive function. In rodents, kisspeptin perikarya are located in 2 major populations: the anteroventral periventricular nucleus and the hypothalamic arcuate nucleus (ARC). These nuclei are believed to play functionally distinct roles in the control of reproduction. The anteroventral periventricular nucleus population is thought to be critical in the generation of the LH surge. However, the physiological role played by the ARC kisspeptin neurons remains to be fully elucidated. We used bilateral stereotactic injection of recombinant adeno-associated virus encoding kisspeptin antisense into the ARC of adult female rats to investigate the physiological role of kisspeptin neurons in this nucleus. Female rats with kisspeptin knockdown in the ARC displayed a significantly reduced number of both regular and complete oestrous cycles and significantly longer cycles over the 100-day period of the study. Further, kisspeptin knockdown in the ARC resulted in a decrease in LH pulse frequency. These data suggest that maintenance of ARC-kisspeptin levels is essential for normal pulsatile LH release and oestrous cyclicity.
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Affiliation(s)
- K E Beale
- Section of Investigative Medicine (K.E.B., J.S.K.-J., J.V.G., E.K.H., E.L.T., M.L.S., A.H.S., H.C.G., A.K.M., W.S.D., S.R.B., K.G.M.) and Institute of Reproductive and Developmental Biology (J.M.M., S.F.), Imperial College London, London W12 0NN, United Kingdom; and Division of Women's Health (M.H.H., X.F.L., K.T.O.), School of Medicine, King's College London, London SE1 1UL, United Kingdom
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Classification criteria for distinguishing cortisol responders from nonresponders to psychosocial stress: evaluation of salivary cortisol pulse detection in panel designs. Psychosom Med 2013; 75:832-40. [PMID: 24184845 DOI: 10.1097/psy.0000000000000002] [Citation(s) in RCA: 252] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Hypothalamic-pituitary-adrenal axis reactivity to acute stimulation is frequently assessed by repeated sampling of salivary cortisol. Researchers often strive to distinguish between individuals who show (responders) and those do not show (nonresponders) cortisol responses. For this, fixed threshold classification criteria, such as a 2.5-nmol/l baseline-to-peak increase, are frequently used. However, the performance of such criteria has not been systematically evaluated. METHODS Repeated salivary cortisol data from 504 participants exposed to either the Trier Social Stress Test (TSST; n = 309) or a placebo protocol (n = 195) were used for analyses. To obtain appropriate classifications of cortisol responders versus nonresponders, a physiologically plausible, autoregressive latent trajectory (ALT) mixture model was fitted to these data. Response classifications according to the ALT model and information on the experimental protocol (TSST versus placebo TSST) were then used to evaluate the performance of different proposed classifier proxies by receiver operating characteristics. RESULTS Moment structure of cortisol time series was adequately accounted for by the proposed ALT model. The commonly used 2.5-nmol/l criterion was found to be overly conservative, resulting in a high rate of 16.5% false-negative classifications. Lowering this criterion to 1.5 nmol/l or using a percentage baseline-to-peak increase of 15.5% as a threshold yielded improved performance (39.3% and 26.7% less misclassifications, respectively). CONCLUSIONS Alternative classification proxies (1.5 nmol/l or 15.5% increase) are able to effectively distinguish between cortisol responders and nonresponders and should be used in future research, whenever statistical response class allocation is not feasible.
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Rosenfield RL, Bordini B, Yu C. Comparison of detection of normal puberty in girls by a hormonal sleep test and a gonadotropin-releasing hormone agonist test. J Clin Endocrinol Metab 2013; 98:1591-601. [PMID: 23457407 PMCID: PMC3615202 DOI: 10.1210/jc.2012-4136] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The magnitude of sleep-related gonadotropin rise required to activate pubertal feminization is not established. OBJECTIVE The objective of the study was to determine the normal relationship of pubertal hormone responses to sleep and to GnRH agonist (GnRHag) challenge across the female pubertal transition. DESIGN/SETTING This was a prospective study in a General Clinical Research Center. PARTICIPANTS Sixty-two healthy 6- to 13-year-old volunteer girls participated in the study. INTERVENTIONS Interventions included overnight blood sampling followed by GnRHag (leuprolide acetate) injection. PRIMARY OUTCOME VARIABLES The primary outcome variables included LH, FSH, and estradiol. RESULTS LH levels rose steadily during sleep and after GnRHag throughout the prepubertal years. The LH response to sleep and GnRHag correlated well across groups (eg, r = 0.807, peak vs 4 h post-GnRHag value); however, this correlation was less robust than in boys (r = 0.964, P < .01). Sleep peak LH of 1.3 U/L or greater had 85% sensitivity and 2.1 U/L or greater 96% specificity for detecting puberty (thelarche). The LH 1-hour post-GnRHag value of 3.2 U/L or greater had 95% sensitivity and 5.5 U/L or greater 96% specificity for detecting puberty. Girls entered puberty at lower LH levels than boys. FSH levels rose day and night during the prepubertal years to reach 1.0 U/L or greater during puberty but discriminated puberty poorly. Estradiol of 34 pg/mL or greater at 20-24 hours after GnRHag was 95% sensitive and 60 pg/mL or greater was 95% specific for puberty. Thirty-six percent of overweight early pubertal girls had meager hormonal evidence of puberty. CONCLUSIONS These data suggest that sleep-related pubertal hormone levels critical for puberty are normally reflected in the responses to GnRHag testing across the normal female pubertal transition. Inconsistencies between clinical and hormonal staging may arise from peripubertal cyclicity of neuroendocrine function and from excess adiposity.
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Affiliation(s)
- Robert L Rosenfield
- Section of Adult and Pediatric Endocrinology, Metabolism, and Diabetes, University of Chicago Medical Center, Chicago, IL 60637, USA.
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Rosenfield RL, Bordini B, Yu C. Comparison of detection of normal puberty in boys by a hormonal sleep test and a gonadotropin-releasing hormone agonist test. J Clin Endocrinol Metab 2012; 97:4596-604. [PMID: 23043188 PMCID: PMC3513543 DOI: 10.1210/jc.2012-2722] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The magnitude of sleep-related gonadotropin rise required to activate pubertal gonadal function is not established. OBJECTIVE Our objective was to determine the normal relationship between sleep-related pubertal hormone levels and pituitary-testicular responsiveness to a GnRH agonist (GnRHag) test across the pubertal transition. DESIGN/SETTING AND PARTICIPANTS: We conducted a prospective study in a General Clinical Research Center with healthy 9- to 15-yr-old volunteer boys. INTERVENTIONS INTERVENTIONS included overnight blood sampling followed by leuprolide acetate injection (10 μg/kg). PRIMARY OUTCOME VARIABLES LH, FSH, and testosterone levels were evaluated. RESULTS LH levels during sleep and post-GnRHag rose steadily during the late prepubertal years. Sleep peak LH correlated highly with the LH response to GnRHag across groups (r = 0.913). A sleep peak LH level of at least 3.7 U/liter predicted pubertal testicular activation with 100% accuracy. LH of at least 14.8 and at least 19.0 U/liter 4 h after GnRHag, respectively, predicted puberty with 100% sensitivity/94% specificity and 100% specificity/94% sensitivity. Overweight pubertal boys had transiently prolonged responses to GnRHag. FSH rose during both waking and sleeping hours during the prepubertal years, and all pubertal boys had an FSH level of at least 0.9 U/liter awake and at least 1.2 U/liter asleep. Sleep LH was more closely related than FSH to testicular size. CONCLUSIONS These data suggest that a critical LH level during sleep (≥3.7 U/liter) heralds the onset of pubertal virilization and that this level is predictable by LH of at least 14.8-19 U/liter 4 h after GnRHag. These data also suggest that LH stimulation of testicular androgen production plays a role in stimulating testicular tubule growth once a critical level of FSH is achieved.
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Affiliation(s)
- Robert L Rosenfield
- University of Chicago Medical Center, Section of Adult and Pediatric Endocrinology, Metabolism, and Diabetes, 5841 South Maryland Avenue (MC-5053), Chicago, Illinois 60637, USA.
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12
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Grachev P, Li XF, Lin YS, Hu MH, Elsamani L, Paterson SJ, Millar RP, Lightman SL, O’Byrne KT. GPR54-dependent stimulation of luteinizing hormone secretion by neurokinin B in prepubertal rats. PLoS One 2012; 7:e44344. [PMID: 23028524 PMCID: PMC3460954 DOI: 10.1371/journal.pone.0044344] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Accepted: 08/01/2012] [Indexed: 11/18/2022] Open
Abstract
Kisspeptin, neurokinin B (NKB) and dynorphin A (Dyn) are coexpressed within KNDy neurons that project from the hypothalamic arcuate nucleus (ARC) to GnRH neurons and numerous other hypothalamic targets. Each of the KNDy neuropeptides has been implicated in regulating pulsatile GnRH/LH secretion. In isolation, kisspeptin is generally known to stimulate, and Dyn to inhibit LH secretion. However, the NKB analog, senktide, has variously been reported to inhibit, stimulate or have no effect on LH secretion. In prepubertal mice, rats and monkeys, senktide stimulates LH secretion. Furthermore, in the monkey this effect is dependent on kisspeptin signaling through its receptor, GPR54. The present study tested the hypotheses that the stimulatory effects of NKB on LH secretion in intact rats are mediated by kisspeptin/GPR54 signaling and are independent of a Dyn tone. To test this, ovarian-intact prepubertal rats were subjected to frequent automated blood sampling before and after intracerebroventricular injections of KNDy neuropeptide analogs. Senktide robustly induced single LH pulses, while neither the GPR54 antagonist, Kp-234, nor the Dyn agonist and antagonist (U50488 and nor-BNI, respectively) had an effect on basal LH levels. However, Kp-234 potently blocked the senktide-induced LH pulses. Modulation of the Dyn tone by U50488 or nor-BNI did not affect the senktide-induced LH pulses. These data demonstrate that the stimulatory effect of NKB on LH secretion in intact female rats is dependent upon kisspeptin/GPR54 signaling, but not on Dyn signaling.
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Affiliation(s)
- Pasha Grachev
- Division of Women’s Health, School of Medicine, King’s College London, London, United Kingdom
| | - Xiao Feng Li
- Division of Women’s Health, School of Medicine, King’s College London, London, United Kingdom
| | - Yuan Shao Lin
- Division of Women’s Health, School of Medicine, King’s College London, London, United Kingdom
| | - Ming Han Hu
- Division of Women’s Health, School of Medicine, King’s College London, London, United Kingdom
| | - Leena Elsamani
- Division of Women’s Health, School of Medicine, King’s College London, London, United Kingdom
| | - Stewart J. Paterson
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, King’s College London, London, United Kingdom
| | - Robert P. Millar
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa
- University of Cape Town/Medical Research Council Research Group for Receptor Biology, Division of Medical Biochemistry, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Stafford L. Lightman
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, United Kingdom
| | - Kevin T. O’Byrne
- Division of Women’s Health, School of Medicine, King’s College London, London, United Kingdom
- * E-mail: kevin.o’
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Lin Y, Li X, Lupi M, Kinsey-Jones JS, Shao B, Lightman SL, O'Byrne KT. The role of the medial and central amygdala in stress-induced suppression of pulsatile LH secretion in female rats. Endocrinology 2011; 152:545-55. [PMID: 21159851 PMCID: PMC3101805 DOI: 10.1210/en.2010-1003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Stress exerts profound inhibitory effects on reproductive function by suppressing the pulsatile release of GnRH and therefore LH. Although the mechanisms by which stressors disrupt the hypothalamic GnRH pulse generator remain to be fully elucidated, numerous studies have implicated the amygdala, especially its medial (MeA) and central nuclei (CeA), as key modulators of the neuroendocrine response to stress. In the present study, we investigated the roles of the MeA and CeA in stress-induced suppression of LH pulses. Ovariectomized rats received bilateral ibotenic acid or sham lesions targeting the MeA or CeA; blood samples (25 μl) were taken via chronically implanted cardiac catheters every 5 min for 6 h for the measurement of LH pulses. After 2 h of baseline sampling, the rats were exposed to either: restraint (1 h), insulin-induced hypoglycemia (IIH) (0.3 U/kg, iv), or lipopolysaccharide (LPS) (25 μg/kg, iv) stress. The restraint but not IIH or LPS stress-induced suppression of LH pulses was markedly attenuated by the MeA lesions. In contrast, CeA lesioning attenuated LPS, but not restraint or IIH stress-induced suppression of LH pulses. Moreover, after restraint stress, the number of Fos-positive neurons and the percentage of glutamic acid decarboxylase(67) neurons expressing Fos was significantly greater in the GnRH-rich medial preoptic area (mPOA) of rats with intact, rather than lesioned, MeA. These data indicate that the MeA and CeA play key roles in psychogenic and immunological stress-induced suppression of the GnRH pulse generator, respectively, and the MeA-mediated effect may involve γ-aminobutyric acid ergic signaling within the mPOA.
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Affiliation(s)
- Yuanshao Lin
- Division of Women's Health, School of Medicine, King's College London, 2.92W Hodgkin Building, Guy's Campus, London, SE1 1UL, UK
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Yonezawa T, Mogi K, Li JY, Sako R, Manabe N, Yamanouchi K, Nishihara M. Effects of estrogen on growth hormone pulsatility in peripheral blood and neuropeptide profiles in the cerebrospinal fluid of goats. J Reprod Dev 2011; 57:280-7. [PMID: 21242654 DOI: 10.1262/jrd.10-118s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously reported that growth hormone (GH) pulses were negatively associated with neuropeptide Y (NPY) profiles in cerebrospinal fluid (CSF) of the third ventricle of Shiba goats. In addition, while most GH pulses were coincident with GH-releasing hormone (GHRH) pulses, there was no correlation between GH and somatostatin (SRIF) levels. The present study was performed to elucidate the relationship between GH pulses and these neuropeptide levels in CSF when estradiol (1.0 mg/head) was subcutaneously administered to ovariectomized goats. CSF and plasma samples were collected every 15 min for 18 h (from 6 h before to 12 h after injection). GH levels in peripheral blood and GHRH, SRIF and NPY levels in CSF were measured by radioimmunoassay. Pulse/trough characteristics and correlations were assessed by the ULTRA algorithm and cross-correlation analysis. Before estradiol was injected, significant coincidence was found between GHRH pulses and GH pulses, and negative coincidence was found between NPY troughs and GH pulses. Six to 12 h after estradiol injection, the amplitude and area under the curve (AUC) of the GH pulses were markedly increased. The duration and AUC of the GHRH pulses in the CSF were also increased, and stronger synchrony of GHRH with GH was observed. In contrast, the baseline of NPY was significantly decreased, and the negative correlation between the GH pulses and NPY troughs disappeared. The parameters of SRIF troughs were not clearly changed. These observations suggest that estrogen enhances the pattern of secretion of GH in the goat via enhancement of GHRH pulses and decrease of NPY levels.
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Affiliation(s)
- Tomohiro Yonezawa
- Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo, Japan
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15
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Panunzi S, De Gaetano A, Mingrone G. Advantages of the single delay model for the assessment of insulin sensitivity from the intravenous glucose tolerance test. Theor Biol Med Model 2010; 7:9. [PMID: 20298586 PMCID: PMC2858103 DOI: 10.1186/1742-4682-7-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 03/18/2010] [Indexed: 12/27/2022] Open
Abstract
Background The Minimal Model, (MM), used to assess insulin sensitivity (IS) from Intra-Venous Glucose-Tolerance Test (IVGTT) data, suffers from frequent lack of identifiability (parameter estimates with Coefficients of Variation (CV) less than 52%). The recently proposed Single Delay Model (SDM) is evaluated as a practical alternative. Methods The SDM was applied to 74 IVGTTs from lean (19), overweight (22), obese (22) and morbidly obese (11) subjects. Estimates from the SDM (KxgI) were compared with the corresponding MM (SI), 1/HOMA-IR index and Euglycemic-Hyperinsulinemic Clamp (M-EHC over 7 subjects) estimates. Results KxgI was identifiable in 73 out of 74 subjects (CV = 69% in the 74th subject) and ranged from 1.25 × 10-5 to 4.36 × 10-4min-1pM-1; SI CV was >52% in 36 subjects (up to 2.36 × 109%) and presented 18 extreme values (≤ 1.5 × 10-12 or ≥ 3.99). KxgI correlated well with 1/HOMA-IR (r = 0.56, P < 0.001), whereas the correlations KxgI-SI and 1/HOMA-IR-SI were high (r = 0.864 and 0.52 respectively) and significant (P < 0.001 in both cases) only in the non-extreme SI sub-sample (56 subjects). Correlations KxgI vs. M-EHC and SI vs. M-EHC were positive (r = 0.92, P = 0.004 and r = 0.83, P = 0.02 respectively). KxgI decreased for higher BMI's (P < 0.001), SI significantly so only over the non-extreme-SI sub-sample. The Acute Insulin Response Index was also computed and the expected inverse (hyperbolic) relationship with the KxgI observed. Conclusions Precise estimation of insulin sensitivity over a wide range of BMI, stability of all other model parameters, closer adherence to accepted physiology make the SDM a useful alternative tool for the evaluation of insulin sensitivity from the IVGTT.
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Affiliation(s)
- Simona Panunzi
- CNR-Institute of Systems Analysis and Computer Science (IASI), BioMathLab, Rome, Italy.
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Getty-Kaushik L, Viereck JC, Goodman JM, Guo Z, LeBrasseur NK, Richard AMT, Flanagan JN, Yaney GC, Hamilton JA, Tornheim K. Mice deficient in phosphofructokinase-M have greatly decreased fat stores. Obesity (Silver Spring) 2010; 18:434-40. [PMID: 19779479 PMCID: PMC2871150 DOI: 10.1038/oby.2009.295] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Synthesis of triacylglycerol requires the glucose-derived glycerol component, and glucose uptake has been viewed as the rate-limiting step in glucose metabolism in adipocytes. Furthermore, adipose tissue contains all three isoforms of the glycolytic enzyme phosphofructokinase (PFK). We here report that mice deficient in the muscle isoform PFK-M have greatly reduced fat stores. Mice with disrupted activity of the PFK-M distal promoter were obtained from Lexicon Pharmaceuticals, developed from OmniBank OST#56064. Intra-abdominal fat was measured by magnetic resonance imaging of the methylene proton signal. Lipogenesis from labeled glucose was measured in isolated adipocytes. Lipolysis (glycerol and free fatty acid release) was measured in perifused adipocytes. Intra-abdominal fat in PFK-M-deficient female mice (5-10 months old) was 17 +/- 3% of that of wild-type littermates (n = 4; P < 0.02). Epididymal fat weight in 15 animals (7-9.5 months) was 34 +/- 4% of control littermate (P < 0.002), with 10-30% lower body weight. Basal and insulin-stimulated lipogenesis in PFK-M-deficient epididymal adipocytes was 40% of the rates in cells from heterozygous littermates (n = 3; P < 0.05). The rate of isoproterenol-stimulated lipolysis in wild-type adipocytes declined approximately 10% after 1 h and 50% after 2 h; in PFK-M-deficient cells it declined much more rapidly, 50% in 1 h and 90% in 2 h, and lipolytic oscillations appeared to be damped (n = 4). These results indicate an important role for PFK-M in adipose metabolism. This may be related to the ability of this isoform to generate glycolytic oscillations, because such oscillations may enhance the production of the triacylglycerol precursor alpha-glycerophosphate.
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Affiliation(s)
- Lisa Getty-Kaushik
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jason C. Viereck
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jessie M. Goodman
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Zifang Guo
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Nathan K. LeBrasseur
- Section of Endocrinology, Diabetes and Nutrition, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Ann-Marie T. Richard
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
| | - John N. Flanagan
- Section of Endocrinology, Diabetes and Nutrition, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Gordon C. Yaney
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - James A. Hamilton
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Keith Tornheim
- Obesity Research Center, Evans Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
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Li XF, Kinsey-Jones JS, Cheng Y, Knox AMI, Lin Y, Petrou NA, Roseweir A, Lightman SL, Milligan SR, Millar RP, O'Byrne KT. Kisspeptin signalling in the hypothalamic arcuate nucleus regulates GnRH pulse generator frequency in the rat. PLoS One 2009; 4:e8334. [PMID: 20016824 PMCID: PMC2789414 DOI: 10.1371/journal.pone.0008334] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 11/24/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Kisspeptin and its G protein-coupled receptor (GPR) 54 are essential for activation of the hypothalamo-pituitary-gonadal axis. In the rat, the kisspeptin neurons critical for gonadotropin secretion are located in the hypothalamic arcuate (ARC) and anteroventral periventricular (AVPV) nuclei. As the ARC is known to be the site of the gonadotropin-releasing hormone (GnRH) pulse generator we explored whether kisspeptin-GPR54 signalling in the ARC regulates GnRH pulses. METHODOLOGY/PRINCIPAL FINDINGS We examined the effects of kisspeptin-10 or a selective kisspeptin antagonist administration intra-ARC or intra-medial preoptic area (mPOA), (which includes the AVPV), on pulsatile luteinizing hormone (LH) secretion in the rat. Ovariectomized rats with subcutaneous 17beta-estradiol capsules were chronically implanted with bilateral intra-ARC or intra-mPOA cannulae, or intra-cerebroventricular (icv) cannulae and intravenous catheters. Blood samples were collected every 5 min for 5-8 h for LH measurement. After 2 h of control blood sampling, kisspeptin-10 or kisspeptin antagonist was administered via pre-implanted cannulae. Intranuclear administration of kisspeptin-10 resulted in a dose-dependent increase in circulating levels of LH lasting approximately 1 h, before recovering to a normal pulsatile pattern of circulating LH. Both icv and intra-ARC administration of kisspeptin antagonist suppressed LH pulse frequency profoundly. However, intra-mPOA administration of kisspeptin antagonist did not affect pulsatile LH secretion. CONCLUSIONS/SIGNIFICANCE These data are the first to identify the arcuate nucleus as a key site for kisspeptin modulation of LH pulse frequency, supporting the notion that kisspeptin-GPR54 signalling in this region of the mediobasal hypothalamus is a critical neural component of the hypothalamic GnRH pulse generator.
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Affiliation(s)
- Xiao-Feng Li
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - James S. Kinsey-Jones
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - Yewsong Cheng
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - Alice M. I. Knox
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - Yuanshao Lin
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - Nikoletta A. Petrou
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - Antonia Roseweir
- Medical Research Council Human Reproductive Sciences Unit, The Queens Medical Research Institute, Edinburgh, United Kingdom
| | - Stafford L. Lightman
- Henry Wellcome Laboratory for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, United Kingdom
| | - Stuart R. Milligan
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
| | - Robert P. Millar
- Medical Research Council Human Reproductive Sciences Unit, The Queens Medical Research Institute, Edinburgh, United Kingdom
- Division of Medical Biochemistry, University of Cape Town, Cape Town, South Africa
| | - Kevin T. O'Byrne
- Division of Reproduction and Endocrinology, King's College London, London, United Kingdom
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Bordini B, Littlejohn E, Rosenfield RL. Blunted sleep-related luteinizing hormone rise in healthy premenarcheal pubertal girls with elevated body mass index. J Clin Endocrinol Metab 2009; 94:1168-75. [PMID: 19190110 PMCID: PMC2682481 DOI: 10.1210/jc.2008-1655] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Our objective was to determine whether excessive adiposity is associated with alteration of the normal hormonal changes of early pubertal girls. DESIGN AND PARTICIPANTS Healthy 6.4- to 9.5-yr-old, prepubertal (PRE, n = 20) and 9.4- to 13.0-yr-old pubertal premenarcheal volunteers (PUB, n = 20) were divided into excessive-weight (EW) or normal-weight (NW) groups according to the 85th percentile body mass index. INTERVENTIONS AND SETTING: Overnight blood sampling; GnRH agonist (GnRHag), low-dose ACTH, oral glucose tolerance tests, and pelvic ultrasonograms were performed in our Clinical Research Center. RESULTS EW girls were similar in age and baseline and ACTH- and GnRHag-stimulated androgen levels to stage-matched NW girls. However, the sleep-related LH rise was blunted in EW-PUB girls compared with NW-PUB girls. The sleep-related rise of mean LH in EW-PUB [0.68 +/- 0.35 (sem) U/liter] was insignificant, less than that of NW-PUB (2.1 +/- 0.45, P < 0.05) and not significantly different from that of PRE girls (0.08+/-0.03). EW-PUB had slower LH pulse frequency and a lower rise in LH pulse amplitude during sleep than NW-PUB girls (both P < 0.05). Overnight FSH patterns paralleled LH patterns, whereas estradiol levels were similar in stage-matched NW and EW groups, differing between stages as expected. Early morning and peak LH, FSH, and estradiol responses to GnRHag were similar in EW-PUB and NW-PUB and significantly greater than those of PRE girls. CONCLUSIONS Healthy EW-PUB girls have significantly blunted sleep-related LH production. These data suggest that excess adiposity, in the absence of sex steroid excess, may subtly suppress hypothalamic-pituitary-gonadal function in premenarcheal pubertal girls.
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Affiliation(s)
- Brian Bordini
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago Pritzker School of Medicine, Chicago, Illinois 60637, USA.
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Cobelli C, Man CD, Sparacino G, Magni L, De Nicolao G, Kovatchev BP. Diabetes: Models, Signals, and Control. IEEE Rev Biomed Eng 2009; 2:54-96. [PMID: 20936056 PMCID: PMC2951686 DOI: 10.1109/rbme.2009.2036073] [Citation(s) in RCA: 369] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The control of diabetes is an interdisciplinary endeavor, which includes a significant biomedical engineering component, with traditions of success beginning in the early 1960s. It began with modeling of the insulin-glucose system, and progressed to large-scale in silico experiments, and automated closed-loop control (artificial pancreas). Here, we follow these engineering efforts through the last, almost 50 years. We begin with the now classic minimal modeling approach and discuss a number of subsequent models, which have recently resulted in the first in silico simulation model accepted as substitute to animal trials in the quest for optimal diabetes control. We then review metabolic monitoring, with a particular emphasis on the new continuous glucose sensors, on the analyses of their time-series signals, and on the opportunities that they present for automation of diabetes control. Finally, we review control strategies that have been successfully employed in vivo or in silico, presenting a promise for the development of a future artificial pancreas and, in particular, discuss a modular architecture for building closed-loop control systems, including insulin delivery and patient safety supervision layers. We conclude with a brief discussion of the unique interactions between human physiology, behavioral events, engineering modeling and control relevant to diabetes.
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Affiliation(s)
- Claudio Cobelli
- Department of Information Engineering, University of Padova, Via Gradenigo 6B, 35131 Padova, Italy
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Via Gradenigo 6B, 35131 Padova, Italy
| | - Giovanni Sparacino
- Department of Information Engineering, University of Padova, Via Gradenigo 6B, 35131 Padova, Italy
| | - Lalo Magni
- Department of Computer Engineering and Systems Science, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy
| | - Giuseppe De Nicolao
- Department of Computer Engineering and Systems Science, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy
| | - Boris P. Kovatchev
- Department of Psychiatry and Neurobehavioral Sciences, P.O. Box 40888, University of Virginia, Charlottesville, VA 22903 USA
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Veldhuis JD, Keenan DM, Pincus SM. Motivations and methods for analyzing pulsatile hormone secretion. Endocr Rev 2008; 29:823-64. [PMID: 18940916 PMCID: PMC2647703 DOI: 10.1210/er.2008-0005] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 09/16/2008] [Indexed: 01/05/2023]
Abstract
Endocrine glands communicate with remote target cells via a mixture of continuous and intermittent signal exchange. Continuous signaling allows slowly varying control, whereas intermittency permits large rapid adjustments. The control systems that mediate such homeostatic corrections operate in a species-, gender-, age-, and context-selective fashion. Significant progress has been made in understanding mechanisms of adaptive interglandular signaling in vivo. Principal goals are to understand the physiological origins, significance, and mechanisms of pulsatile hormone secretion. Key analytical issues are: 1) to quantify the number, size, shape, and uniformity of pulses, nonpulsatile (basal) secretion, and elimination kinetics; 2) to evaluate regulation of the axis as a whole; and 3) to reconstruct dose-response interactions without disrupting hormone connections. This review will focus on the motivations driving and the methodologies used for such analyses.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Department of Internal Medicine, Mayo Medical School, Mayo School of Graduate Medical Education, Center for Translational Science Activities, Mayo Clinic, Rochester, Minnesota 55905, USA.
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21
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Li XF, Kinsey-Jones JS, Knox AMI, Wu XQ, Tahsinsoy D, Brain SD, Lightman SL, O'Byrne KT. Neonatal lipopolysaccharide exposure exacerbates stress-induced suppression of luteinizing hormone pulse frequency in adulthood. Endocrinology 2007; 148:5984-90. [PMID: 17872370 PMCID: PMC2225523 DOI: 10.1210/en.2007-0710] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Early life exposure to immunological challenge has programming effects on the adult hypothalamo-pituitary-adrenocortical axis stress responsivity, and stress is known to suppress GnRH pulse generator activity, especially LH pulses. We investigated the effects of neonatal exposure to endotoxin on stress-induced suppression of pulsatile LH secretion and the involvement of corticotropin-releasing factor (CRF) receptor mechanisms in adult rats. Pups at 3 and 5 d of age were administered lipopolysaccharide (LPS, 50 microg/kg, ip). At 12 wk of age, they were ovariectomized and implanted with sc 17beta-estradiol capsules and i.v. cannulas. Blood samples (25 microl) were collected every 5 min for 5 h for LH measurement. After 2 h of sampling, rats were given LPS (25 microg/kg, iv). CRF and CRF-R1 and CRF-R2 receptor mRNA was determined by RT-PCR in medial preoptic area (mPOA) micropunches collected at 3 h after LPS administration. There was no difference in basal LH pulse frequency between neonatal LPS- and neonatal saline-treated controls. However, neonatal endotoxin-treated rats exhibited a significantly greater LPS stress-induced suppression of LH pulse frequency. Basal mPOA CRF-R1 expression was unchanged in neonatal LPS- and neonatal saline-treated rats. However, CRF-R1 expression was significantly increased in response to LPS stress in neonatal LPS-treated animals but not in neonatal saline-treated controls. CRF and CRF-R2 expression was unchanged in all treatment groups. These data demonstrate that exposure to bacterial endotoxin in early neonatal life programs long-term sensitization of the GnRH pulse generator to the inhibitory influence of stress in adulthood, an effect that might involve up-regulation of CRF-R1 expression in the mPOA.
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Affiliation(s)
- X F Li
- Division of Reproduction and Endocrinology, 2.36D New Hunt's House, King's College London, Guy's Campus, London, United Kingdom
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22
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Lafuente A, Cabaleiro T, Cano P, Esquifino AI. Toxic effects of methoxychlor on the episodic prolactin secretory pattern: possible mediated effects of nitric oxide production. J Circadian Rhythms 2006; 4:3. [PMID: 16515688 PMCID: PMC1450319 DOI: 10.1186/1740-3391-4-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 03/03/2006] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND This work addresses the issue of whether methoxychlor (MTX) exposure may modify the ultradian secretion of prolactin through changes in the synthesis of nitric oxide (NO) induced by Nomega-nitro-L-arginine methyl ester (L-NAME) in the hypothalamic-pituitary axis. Associated changes in dopamine (DA) content in the anterior (AH), mediobasal (MBH) and posterior hypothalamus (PH) and median eminence (ME) were evaluated. METHODS Two groups of animals (MTX and MTX+L-NAME treated) received subcutaneous (sc) injections of MTX at a dose of 25 mg/kg/day for one month. The other two groups of animals (control and L-NAME treated) received sc vehicle injections (0.5 mL/day of sesame oil), during the same period of time to be used as controls. Forty hours before the day of the experiment, animals were anaesthetized with intrapritoneal injections of 2.5% tribromoethanol in saline and atrial cannulas were implanted through the external jugular vein. Plasma was continuously extracted in Hamilton syringes coupled to a peristaltic bomb in tubes containing phosphate-gelatine buffer (to increase viscosity). The plasma was obtained by decantation and kept every 7 minutes for the measurement of plasma prolactin levels through a specific radioimmnunoassay and DA concentration by high-pressure liquid chromatography (HPLC). RESULTS Prolactin release in animals from all experimental groups analyzed was episodic. Mean plasma prolactin levels during the bleeding period, and the absolute pulse amplitude were increased after MTX or Nomega-nitro-L-arginine methyl ester (L-NAME) administration. However MTX and L-NAME did not modify any other parameter studied with the exception of relative pulse amplitude in MTX treated rats. L-NAME administration to rats treated with the pesticide reduced mean plasma prolactin levels and the absolute amplitude of prolactin peaks. Peak duration, frequency and relative amplitude of prolactin peaks were not changed in the group of rats treated with MTX plus L-NAME as compared to either control or MTX treated rats. Whereas MTX decreased DA content in the ME and increased it in the AH, its content did not change in the MBH or PH, as compared to the values found in controls. Also, L-NAME administration decreased DA content in the ME as compared to controls. However, L- NAME administration to MTX exposed rats, markedly increased DA content in the ME as compared to either MTX treated or control rats. L-NAME administration increased DA content in the AH as compared to the values found in non-treated rats. However L-NAME administration to MTX exposed rats did not modify DA content as compared to either MTX treated or control rats. L-NAME administration did not modify DA content at the MBH nor in saline treated nor in MTX treated rats. However, the values of DA in the MBH in MTX plus L-NAME treated animals were statistically decreased as compared to L-NAME treated rats. In the PH, L-NAME administration increased DA content as compared to the values found in non-treated animals. L-NAME administration to MTX exposed rats also increased DA content as compared to either MTX treated or control rats. CONCLUSION The results suggest the existence of an interaction between MTX and L-NAME in the modulation of the ultradian prolactin secretion at the pituitary levels. The possibility of an indirect effect mediated by changes in DA content at the ME requires further examination.
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Affiliation(s)
- Anunciación Lafuente
- Laboratorio de Toxicología, Facultad de Ciencias, Universidad de Vigo, Campus de Orense, Las Lagunas, 32004 Orense, Spain
| | - Teresa Cabaleiro
- Laboratorio de Toxicología, Facultad de Ciencias, Universidad de Vigo, Campus de Orense, Las Lagunas, 32004 Orense, Spain
| | - Pilar Cano
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain
| | - Ana I Esquifino
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain
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Lado-Abeal J, Robert-McComb JJ, Qian XP, Leproult R, Van Cauter E, Norman RL. Sex differences in the neuroendocrine response to short-term fasting in rhesus macaques. J Neuroendocrinol 2005; 17:435-44. [PMID: 15946161 DOI: 10.1111/j.1365-2826.2005.01323.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
When energy intake is restricted in mammals, there are neuroendocrine adjustments in the secretion of reproductive and metabolic hormones to reallocate energy for vital functions. In the present study, we investigated whether there were differences in the luteinising hormone (LH), growth hormone (GH) and cortisol responses to a 48-h fast in adult gonad-intact male and female rhesus macaques. In both male and female macaques, blood glucose levels were significantly lower in fasted than in control studies, and levels were higher in males than in females. Male rhesus monkeys had significantly lower (P < 0.01) mean serum LH levels after a 48-h fast than under fed conditions and this was attributable primarily to a decrease in the amount of LH released during each secretory episode. In fasted females, serum LH levels were significantly greater (P < 0.05) than during the fed conditions but no differences were found in pulse amplitude or in the number of pulses. Almost twice as many GH pulses were observed in both males and females during fasting but there was no difference in either mean serum GH levels or pulse amplitude between control and fasted studies. A typical diurnal profile in cortisol levels was observed in both sexes and both experimental conditions. Under control conditions, male macaques released less cortisol than females, and although fasting increased mean cortisol levels in both males and females, only the males shown a significant rise over levels observed in control studies. The changes in plasma LH and cortisol levels in fasted rhesus macaques are similar to those observed in humans and suggest that gonadotrophin and corticotrophin secretion are more resistant to short-term energy deprivation in female than in male primates.
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Affiliation(s)
- J Lado-Abeal
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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24
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Bowe JE, Li XF, Kinsey-Jones JS, Paterson S, Brain SD, Lightman SL, O'Byrne KT. Calcitonin gene-related peptide-induced suppression of luteinizing hormone pulses in the rat: the role of endogenous opioid peptides. J Physiol 2005; 566:921-8. [PMID: 15905218 PMCID: PMC1464796 DOI: 10.1113/jphysiol.2005.085662] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Calcitonin gene-related peptide (CGRP) is involved in a variety of stress responses in the rat. Central administration of CGRP activates the hypothalamo-pituitary-adrenal axis resulting in increased corticosterone secretion. We have previously shown that central CGRP suppresses the gonadotrophin-releasing hormone (GnRH) pulse generator, specifically LH pulses. Endogenous opioid peptides (EOPs) have been shown to play an important role in stress-induced suppression of the reproductive axis. The aim of the present study was to test the hypothesis that EOPs mediate CGRP-induced suppression of pulsatile LH secretion. Ovariectomized rats were implanted with intracerebroventricular (i.c.v.) and i.v. cannulae. Intravenous administration of the opioid antagonist naloxone (250 microg) completely blocked the suppression of LH pulses induced by 1.5 microg i.c.v. CGRP and significantly attenuated the suppression of pulsatile LH secretion induced by 5 microg i.c.v. CGRP. Furthermore, intravenous administration of naloxone was found to immediately restore normal LH pulse frequency in animals treated 90 min earlier with 1.5 microg i.c.v. CGRP. Co-administration (i.c.v.) of CGRP (1.5 microg) with the mu and kappa opioid receptor-specific antagonists naloxone (10 microg) and norbinaltorphimine (5 microg), respectively, blocked the CGRP-induced suppression of LH pulses, whilst i.c.v. co-administration of CGRP (1.5 microg) with the delta opioid receptor-specific antagonist naltrindole (5 microg) did not. These data provide evidence that EOPs play a pivotal role in mediating the inhibitory effects of CGRP on pulsatile LH secretion in the rat. They also suggest that the mu and kappa, but not the delta, opioid receptors may be responsible for mediating the effects of CGRP on LH pulses.
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Affiliation(s)
- J E Bowe
- Division of Reproducive Health, Endocrinology and Development, New Hunt's House, King's College London, Guy's Campus, London SE1 1UL, UK.
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25
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Getty-Kaushik L, Richard AMT, Corkey BE. Free fatty acid regulation of glucose-dependent intrinsic oscillatory lipolysis in perifused isolated rat adipocytes. Diabetes 2005; 54:629-37. [PMID: 15734837 DOI: 10.2337/diabetes.54.3.629] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Free fatty acids (FFAs) and glycerol oscillate in plasma. This study examined intrinsic lipolytic oscillations within adipocytes. Rat adipocytes were perifused with Krebs-Ringer bicarbonate buffer: 1) +/- 2 mmol/l glucose; 2) +1 micromol/l isoproterenol +/- 2 mmol/l glucose; 3) + increasing oleate; and 4) + increasing percent BSA. At 2 mmol/l glucose, there were 9 +/- 1 glycerol, FFAs, and lactate pulses per hour with a pulse duration of 5 +/- 1 min. Lipolytic stimulation caused a 50-80% increase in the amplitude of lipolytic oscillations. Removal of glucose caused a 40-70% decrease in the amplitude of lipolytic oscillations and disturbed the pulsatility. Exogenous FFAs suppressed lipolysis and oscillatory amplitude, possibly because of increased cytosolic long-chain coenzyme A (LC-CoA). Increasing percent BSA increased stimulated lipolysis and oscillatory amplitude, possibly because of decreased intracellular LC-CoA. These data show, for the first time, intrinsic lipolytic oscillations, which are glucose dependent and modulated by FFAs. We hypothesize that lipolytic oscillations are driven by oscillatory glucose metabolism, which leads to oscillatory relief of LC-CoA inhibition of triglyceride lipase(s). The results contribute to the understanding of physiological and biochemical regulators of lipolysis, such as glucose and FFAs. Lipolytic oscillations may be beneficial in the delivery of FFAs to liver, pancreas, and other tissues.
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Affiliation(s)
- Lisa Getty-Kaushik
- Obesity Research Center, Department of Molecular Medicine, Boston Medical Center, EBRC 840, 650 Albany St., Boston, MA 02118, USA
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26
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Everson CA, Crowley WR. Reductions in circulating anabolic hormones induced by sustained sleep deprivation in rats. Am J Physiol Endocrinol Metab 2004; 286:E1060-70. [PMID: 14871886 DOI: 10.1152/ajpendo.00553.2003] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The main systemic disorders resulting from prolonged sleep deprivation in laboratory animals are a negative energy balance, low circulating thyroid hormones, and host defense impairments. Low thyroid hormones previously have been found caused by altered regulation at the level of the hypothalamus with possible pituitary involvement. The present studies investigated the effects of sleep deprivation on other major anabolic hormonal systems. Plasma growth hormone (GH) concentrations and major secretory bursts were characterized. Insulin-like growth factor I (IGF-I) was evaluated as an integrative marker of peripheral GH effector activity. Prolactin (PRL) was assessed by basal concentrations and by stimulating the pituitary with exogenous thyrotropin-releasing hormone. Leptin was studied for its linkage to metabolic signs of sleep loss and its correspondence to altered neuroendocrine regulation in other disease states. Last, plasma corticosterone was measured to investigate the degree of hypothalamic-pituitary-adrenal activation. Sleep deprivation was produced by the disk-over-water method, a well-established means of selective deprivation of sleep and noninterference with normal waking behaviors. Hormone concentrations were determined in sham comparisons and at intervals during baseline and experimental periods lasting at least 15 days in partially and totally sleep-deprived rats. The results indicate that high-amplitude pulses of GH were nearly abolished and that concentrations of GH, IGF-I, PRL, and leptin all were suppressed by sleep deprivation. Corticosterone concentration was relatively unaffected. Features of these results, such as low GH and low IGF-I, indicate failed negative feedback and point to hypothalamic mechanisms as containing the foci responsible for peripheral signs.
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Affiliation(s)
- Carol A Everson
- Department of Neurology, The Medical College of Wisconsin, Milwaukee, WI 53295, USA.
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Hücking K, Hamilton-Wessler M, Ellmerer M, Bergman RN. Burst-like control of lipolysis by the sympathetic nervous system in vivo. J Clin Invest 2003; 111:257-64. [PMID: 12531882 PMCID: PMC151855 DOI: 10.1172/jci14466] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Rapid oscillations of visceral lipolysis have been reported. To examine the putative role of the CNS in oscillatory lipolysis, we tested the effects of beta(3)-blockade on pulsatile release of FFAs. Arterial blood samples were drawn at 1-minute intervals for 120 minutes from fasted, conscious dogs (n = 7) during the infusion of saline or bupranolol (1.5 micro g/kg/min), a high-affinity beta(3)-blocker. FFA and glycerol time series were analyzed and deconvolution analysis was applied to estimate the rate of FFA release. During saline infusion FFAs and glycerol oscillated in phase at about eight pulses/hour. Deconvolution analysis showed bursts of lipolysis (nine pulses/hour) with time-dependent variation in burst frequency. Bupranolol completely removed rapid FFA and glycerol oscillations. Despite removal of lipolytic bursts, plasma FFAs (0.31 mM) and glycerol (0.06 mM) were not totally suppressed and deconvolution analysis revealed persistent non-oscillatory lipolysis (0.064 mM/min). These results show that lipolysis in the fasting state consists of an oscillatory component, which appears to be entirely dependent upon sympathetic innervation of the adipose tissue, and a non-oscillatory, constitutive component, which persists despite beta(3)-blockade. The extinction of lipid fuel bursts by beta(3)-blockade implies a role for the CNS in the maintenance of cyclic provision of lipid fuels.
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Affiliation(s)
- Katrin Hücking
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
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Cunningham JM, Buxton OM, Weiss RE. Circadian variation in Cushing's disease and pseudo-Cushing states by analysis of F and ACTH pulsatility. J Endocrinol Invest 2002; 25:791-9. [PMID: 12398238 DOI: 10.1007/bf03345514] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Distinguishing pituitary-dependent Cushing's disease from pseudo-Cushing's states can present a diagnostic challenge. Although many studies potentially discriminate between the 2, only the dexamethasone-suppressed corticotropin-releasing hormone (CRF) stimulation test at 15 minutes is 100% sensitive or specific. We measured baseline profiles of F and ACTH in 31 Cushing's disease patients, 11 with pseudo-Cushing's and 17 controls. Venous blood was collected at 30 minute intervals for 24-h. Subjects also had CRF stimulation tests and 2.0 mg/day dexamethasone suppression tests. F and ACTH profiles were analyzed for circadian rhythmicity, variability, and pulsatility. Relative circadian amplitude was decreased in Cushing's disease compared to both pseudo-Cushing's and normal states. Relative pulse amplitude was reduced in Cushing's disease. Because of this dampening of circadian and pulsatile variations, the overall variability of F and ACTH levels around their mean levels as quantified by the intra-series coefficient of variation (CV), was also decreased in Cushing's disease compared to pseudo-Cushing's and normal states. A F 24-h CV<40% was able to distinguish Cushing's disease from pseudo-Cushing's with 100% sensitivity (95% confidence interval (CI), 88-100%) and specificity (CI, 71-100%). An ACTH CV<40% had 97% sensitivity (CI, 83-100%) and 100% specificity (CI, 71-100%). An overnight 8-h F CV <40% also distinguished Cushing's disease from pseudo-Cushing's with 100% sensitivity (CI, 88-100%) and specificity (CI, 71-100%). These data show that a simple index of total temporal variability (the intra-series CV) derived from the analysis of basal F profiles, provides a useful method to distinguish Cushing's disease from pseudo-Cushing's. A F or ACTH CV <40% discriminates Cushing's disease from pseudo-Cushing's and reflects reduced circadian and pulsatile variations.
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Caufriez A, Moreno-Reyes R, Leproult R, Vertongen F, Van Cauter E, Copinschi G. Immediate effects of an 8-h advance shift of the rest-activity cycle on 24-h profiles of cortisol. Am J Physiol Endocrinol Metab 2002; 282:E1147-53. [PMID: 11934681 DOI: 10.1152/ajpendo.00525.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the adaptation of plasma cortisol profiles to an abrupt phase advance of the rest-activity cycle, eight normal young subjects were submitted in a sleep laboratory to an 8-h advance shift of their sleep-wake and dark-light cycles. The shift was achieved by advancing bedtimes from 2300-0700 to 1500-2300. Blood samples were obtained at 20-min intervals for 68 consecutive hours. The shift resulted within 6-9 h in a 3- to 4-h advance of timings of the nadir of the cortisol profile and of the end of the quiescent period but had no immediate effect on the timing of cortisol acrophase. The quiescent period of cortisol secretion was shortened and fragmented. Thus a major advance shift achieved without enforcing sleep deprivation results in a rapid partial adaptation of the temporal profiles of cortisol but also in a marked disruption of the cortisol quiescent period. Sleep onset was consistently followed by a decrease in cortisol concentrations. Conversely, both sleep-wake and dark-light transitions were consistently associated with cortisol secretory pulses.
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Affiliation(s)
- Anne Caufriez
- Laboratoire de Médecine Expérimentale and Centre d'Etudes des Rythmes Biologiques, Université Libre de Bruxelles, B-1070 Brussels, Belgium.
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Meyer J, Sturis J, Katschinski M, Arnold R, Göke B, Byrne MM. Acute hyperglycemia alters the ability of the normal beta-cell to sense and respond to glucose. Am J Physiol Endocrinol Metab 2002; 282:E917-22. [PMID: 11882513 DOI: 10.1152/ajpendo.00427.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) are associated with an impaired ability of the beta-cell to sense and respond to small changes in plasma glucose. The aim of this study was to establish whether acute hyperglycemia per se plays a role in inducing this defect in beta-cell response. Seven healthy volunteers with no family history of NIDDM were studied on two occasions during a 12-h oscillatory glucose infusion with a periodicity of 144 min. Once, low-dose glucose was infused at a mean rate of 6 mg x kg(-1) x min(-1) and amplitude 33% above and below the mean rate, and, once, high-dose glucose was infused at 12 mg x kg(-1) x min(-1) and amplitude 16% above and below the mean rate. Mean glucose levels were significantly higher during the high-dose compared with the low-dose glucose infusion [9.5 +/- 0.8 vs. 6.8 +/- 0.2 mM (P < 0.01)], resulting in increased mean insulin secretion rates [ISRs; 469.1 +/- 43.8 vs. 268.4 +/- 29 pmol/min (P < 0.001)] and mean insulin levels [213.6 +/- 46 vs. 67.9 +/- 10.9 pmol/l (P < 0.008)]. Spectral analysis evaluates the regularity of oscillations in glucose, insulin secretion, and insulin at a predetermined frequency. Spectral power for glucose, ISR, and insulin was reduced during the high-dose glucose infusion [11.8 +/- 1.4 to 7.0 +/- 1.6 (P < 0.02), 7.6 +/- 1.5 to 3.2 +/- 0.5 (P < 0.04), and 10.5 +/- 1.6 to 4.6 +/- 0.7 (P < 0.01), respectively]. In conclusion, short-term infusion of high-dose glucose to obtain glucose levels similar to those previously seen in IGT subjects results in reduced spectral power for glucose, ISR, and insulin. The reduction in spectral power previously observed for ISR in IGT or NIDDM subjects may be due partly to hyperglycemia.
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Affiliation(s)
- Jürgen Meyer
- Clinical Research Unit for Gastrointestinal Endocrinology, Department of Internal Medicine, Philipps University, 35033 Marburg, Germany
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31
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Abstract
Circadian modulation of episodic bursts is recognized as the normal physiological pattern of diurnal variation in plasma cortisol levels. The primary physiological factors underlying these diurnal patterns are the ultradian timing of secretory events, circadian modulation of the amplitude of secretory events, infusion of the hormone from the adrenal gland into the plasma, and clearance of the hormone from the plasma by the liver. Each measured plasma cortisol level has an error arising from the cortisol immunoassay. We demonstrate that all of these three physiological principles can be succinctly summarized in a single stochastic differential equation plus measurement error model and show that physiologically consistent ranges of the model parameters can be determined from published reports. We summarize the model parameters in terms of the multivariate Gaussian probability density and establish the plausibility of the model with a series of simulation studies. Our framework makes possible a sensitivity analysis in which all model parameters are allowed to vary simultaneously. The model offers an approach for simultaneously representing cortisol's ultradian, circadian, and kinetic properties. Our modeling paradigm provides a framework for simulation studies and data analysis that should be readily adaptable to the analysis of other endocrine hormone systems.
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Affiliation(s)
- E N Brown
- Neuroscience Statistics Research Laboratory, Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA.
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32
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Spiegel K, Leproult R, Colecchia EF, L'Hermite-Balériaux M, Nie Z, Copinschi G, Van Cauter E. Adaptation of the 24-h growth hormone profile to a state of sleep debt. Am J Physiol Regul Integr Comp Physiol 2000; 279:R874-83. [PMID: 10956244 DOI: 10.1152/ajpregu.2000.279.3.r874] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In normal men, the majority of GH secretion occurs in a single large postsleep onset pulse that is suppressed during total sleep deprivation. We examined the impact of semichronic partial sleep loss, a highly prevalent condition, on the 24-h growth hormone profile. Eleven young men were studied after six nights of restricted bedtimes (0100-0500) and after 7 nights of extended bedtimes (2100-0900). Slow-wave sleep (SWS) was estimated as the duration of stages III and IV. Slow-wave activity (SWA) was calculated as electroencephalogram power density in the 0.5- to 3-Hz frequency range. During the state of sleep debt, the GH secretory pattern was biphasic, with both a presleep onset "circadian" pulse and a postsleep onset pulse. Postsleep onset GH secretion was negatively related to presleep onset secretion and tended to be positively correlated with the amount of concomitant SWA. When sleep was restricted, both SWS and SWA were increased during early sleep. Unexpectedly, the increase in SWA affected the second, rather than the first, SWA cycle, suggesting that presleep onset GH secretion may have limited SWA in the first cycle, possibly via an inhibition of central GH-releasing hormone activity. Thus neither the GH profile nor the distribution of SWA conformed with predictions from acute sleep deprivation studies, indicating that adaptation mechanisms are operative during chronic partial sleep loss.
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Affiliation(s)
- K Spiegel
- Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA
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33
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Getty L, Panteleon AE, Mittelman SD, Dea MK, Bergman RN. Rapid oscillations in omental lipolysis are independent of changing insulin levels in vivo. J Clin Invest 2000; 106:421-30. [PMID: 10930445 PMCID: PMC314322 DOI: 10.1172/jci7815] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Abnormal fat metabolism plays an important role in the pathogenesis of obesity-related type 2 diabetes mellitus. This study examined whether free fatty acid levels (FFAs), like insulin levels, oscillate rapidly in plasma. Peripheral and portal blood samples from dogs were assayed for FFA, glycerol, glucose, and insulin. FFA and glycerol showed correlated oscillatory profiles, with about 8 pulses/hour. Omental lipolysis was also pulsatile, with about 10 pulses/hour, and insulin levels oscillated rapidly in plasma with about 7 pulses/hour. We applied an insulin clamp, beta-adrenergic blockade, or both together, to determine the driving force behind the FFA oscillation, and we analyzed our findings by approximate entropy (ApEn) for which lower values suggest regular pulses and higher values suggest disorder. Under basal conditions, ApEn was 0.3 +/- 0.2. With insulin not oscillating, FFA still cycled at about 9 pulses/hour and the ApEn was 0.2 +/- 0.1. In contrast, beta-blockade, either in the presence or absence of an insulin clamp, removed the FFA oscillation in three of nine dogs. In the other six dogs, the oscillatory profile was unchanged, but ApEn was significantly higher than basal values, suggesting that the regularity of the profile was disrupted. These results suggest that the FFA oscillation is driven by the central nervous system, not by insulin.
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Affiliation(s)
- L Getty
- University of Southern California Keck School of Medicine, Department of Physiology and Biophysics, Los Angeles, California 90033, USA
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34
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Luderer U, Morgan MS, Brodkin CA, Kalman DA, Faustman EM. Reproductive endocrine effects of acute exposure to toluene in men and women. Occup Environ Med 1999; 56:657-66. [PMID: 10658543 PMCID: PMC1757663 DOI: 10.1136/oem.56.10.657] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES Despite observation of adverse reproductive effects of toluene, including alterations of serum gonadotropins (luteinising hormone (LH) and follicle stimulating hormone (FSH)) in humans, little is known of the mechanism of toxicity. The hypothesis was tested that toluene acutely suppresses pulsatile gonadotropin secretion by measuring LH and FSH at frequent intervals during controlled exposure to toluene. METHODS Women in the follicular and luteal phases of the menstrual cycle and men were randomised to inhale filtered air with or without 50 ppm toluene through a mouthpiece for 3 hours (19% of the OSHA permissible exposure limit). Blood was sampled by intravenous catheter at 20 minute intervals for 3 hours before, 3 hours during, and 3 hours after exposure. Plasma LH, FSH, and testosterone were measured. Pulse amplitude, pulse frequency, and mean concentrations of LH and FSH for each of the 3 hour periods before, during and after exposure to toluene versus sham exposure were calculated with the ULTRA pulse detection program and compared by analysis of variance (ANOVA) with repeated measures. RESULTS In men mean concentrations of LH showed a significant interaction (p < 0.05) between exposure and sampling period, with a greater LH decline during exposure to toluene than sham exposure. However, there was no concomitant effect on testosterone concentrations. The LH pulse frequency of women in the luteal phase showed a trend towards a significant interaction between exposure and sampling period (p = 0.06), with a greater decline in pulse frequency during exposure to toluene than sham exposure. There were no other significant effects of exposure to toluene. CONCLUSIONS Three hour exposure to 50 ppm toluene did not result in abnormal episodic LH or FSH secretion profiles, however, subtle effects on LH secretion in men and women in the luteal phase were found. The clinical relevance of these effects is unclear, indicating the need for further study of reproductive function in exposed workers.
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Affiliation(s)
- U Luderer
- Center for Occupational and Environmental Health, University of California, Irvine, USA
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35
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Van Cauter E, Plat L, Scharf MB, Leproult R, Cespedes S, L'Hermite-Balériaux M, Copinschi G. Simultaneous stimulation of slow-wave sleep and growth hormone secretion by gamma-hydroxybutyrate in normal young Men. J Clin Invest 1997; 100:745-53. [PMID: 9239423 PMCID: PMC508244 DOI: 10.1172/jci119587] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The aim of this study was to investigate, in normal young men, whether gamma-hydroxybutyrate (GHB), a reliable stimulant of slow-wave (SW) sleep in normal subjects, would simultaneously enhance sleep related growth hormone (GH) secretion. Eight healthy young men participated each in four experiments involving bedtime oral administration of placebo, 2.5, 3.0, and 3.5 g of GHB. Polygraphic sleep recordings were performed every night, and blood samples were obtained at 15-min intervals from 2000 to 0800. GHB effects were mainly observed during the first 2 h after sleep onset. There was a doubling of GH secretion, resulting from an increase of the amplitude and the duration of the first GH pulse after sleep onset. This stimulation of GH secretion was significantly correlated to a simultaneous increase in the amount of sleep stage IV. Abrupt but transient elevations of prolactin and cortisol were also observed, but did not appear to be associated with the concomitant stimulation of SW sleep. Thyrotropin and melatonin profiles were not altered by GHB administration. These data suggest that pharmacological agents that reliably stimulate SW sleep, such as GHB, may represent a novel class of powerful GH secretagogues.
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Affiliation(s)
- E Van Cauter
- Department of Medicine, University of Chicago, Illinois 60637, USA.
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36
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Sturis J, Scheen AJ, Leproult R, Polonsky KS, van Cauter E. 24-hour glucose profiles during continuous or oscillatory insulin infusion. Demonstration of the functional significance of ultradian insulin oscillations. J Clin Invest 1995; 95:1464-71. [PMID: 7706450 PMCID: PMC295628 DOI: 10.1172/jci117817] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Under basal and stimulated conditions, normal insulin secretion oscillates with periods in the ultradian 100-150-min range. To test the hypothesis that oscillatory insulin delivery is more efficient in reducing blood glucose levels than continuous administration, nine normal young men were each studied on two occasions during a 28-h period including a period of polygraphically recorded sleep. Endogenous insulin secretion was suppressed by somatostatin, a constant intravenous glucose infusion was administered, and exogenous insulin was infused either at a constant rate or in a sinusoidal pattern with a period of 120 min. The mean glucose level over the 28-h period was 0.72 +/- 0.31 mmol/liter lower when insulin was infused in an oscillatory pattern than when the rate of infusion was constant (P < 0.05). The greater hypoglycemic effect of oscillatory versus constant infusion was particularly marked during the daytime, with the difference averaging 1.04 +/- 0.38 mmol/liter (P < 0.03). Serum insulin levels tended to be lower during oscillatory than constant infusion, although the same amount of exogenous insulin was administered under both conditions. Ultradian insulin oscillations appear to promote more efficient glucose utilization.
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Affiliation(s)
- J Sturis
- Department of Medicine, University of Chicago, Illinois 60637, USA
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37
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Byrne MM, Sturis J, Clément K, Vionnet N, Pueyo ME, Stoffel M, Takeda J, Passa P, Cohen D, Bell GI. Insulin secretory abnormalities in subjects with hyperglycemia due to glucokinase mutations. J Clin Invest 1994; 93:1120-30. [PMID: 8132752 PMCID: PMC294056 DOI: 10.1172/jci117064] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Pancreatic beta-cell function was studied in six subjects with mutations in the enzyme glucokinase (GCK) who were found to have elevated fasting and postprandial glucose levels in comparison to six normoglycemic controls. Insulin secretion rates (ISRs) were estimated by deconvolution of peripheral C-peptide values using a two-compartment model and individual C-peptide kinetics obtained after bolus intravenous injections of biosynthetic human C-peptide. First-phase insulin secretory responses to intravenous glucose and insulin secretion rates over a 24-h period on a weight maintenance diet were not different in subjects with GCK mutations and controls. However, the dose-response curve relating glucose and ISR obtained during graded intravenous glucose infusions was shifted to the right in the subjects with GCK mutations and average ISRs over a glucose range between 5 and 9 mM were 61% lower than those in controls. In the controls, the beta cell was most sensitive to an increase in glucose at concentrations between 5.5 and 6.0 mM, whereas in the patients with GCK mutations the point of maximal responsiveness was increased to between 6.5 and 7.5 mM. Even mutations that resulted in mild impairment of in vitro enzyme activity were associated with a > 50% reduction in ISR. The responsiveness of the beta cell to glucose was increased by 45% in the subjects with mutations after a 42-h intravenous glucose infusion at a rate of 4-6 mg/kg per min. During oscillatory glucose infusion with a period of 144 min, profiles from the subjects with mutations revealed reduced spectral power at 144 min for glucose and ISR compared with controls, indicating decreased ability to entrain the beta cell with exogenous glucose. In conclusion, subjects with mutations in GCK demonstrate decreased responsiveness of the beta cell to glucose manifest by a shift in the glucose ISR dose-response curve to the right and reduced ability to entrain the ultradian oscillations of insulin secretion with exogenous glucose. These results support a key role for the enzyme GCK in determining the in vivo glucose/ISR dose-response relationships and define the alterations in beta-cell responsiveness that occur in subjects with GCK mutations.
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Affiliation(s)
- M M Byrne
- Department of Medicine, University of Chicago, Illinois 60637
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38
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O'Meara NM, Sturis J, Van Cauter E, Polonsky KS. Lack of control by glucose of ultradian insulin secretory oscillations in impaired glucose tolerance and in non-insulin-dependent diabetes mellitus. J Clin Invest 1993; 92:262-71. [PMID: 8325993 PMCID: PMC293585 DOI: 10.1172/jci116560] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Normal subjects demonstrate the presence of ultradian oscillations (period 80-150 min) in insulin secretion rate (ISR) tightly coupled to glucose oscillations of similar period. These oscillations appear to be a function of the feedback loop linking glucose and insulin. The present study was undertaken to determine whether the control by glucose of the ultradian oscillations in insulin secretion is altered in impaired glucose tolerance IGT and in non-insulin-dependent diabetes mellitus (NIDDM). Patients with NIDDM (n = 7), IGT (n = 4), and matched nondiabetic controls (n = 5) were studied under three separate protocols that involved administration of glucose at either a constant rate of 6 mg/kg per min for 28 h or in one of two oscillatory patterns at the same overall mean rate. The amplitude of the oscillations was 33% above and below the mean infusion rate, and their respective periods were 144 min (slow oscillatory infusion) or 96 min (rapid oscillatory infusion). Insulin, C-peptide, and glucose were sampled at 10-min intervals during the last 24 h of each study. ISRs were calculated by deconvolution of C-peptide levels. Analysis of the data showed that (a) the tight temporal coupling between glucose and ISR in the nondiabetic controls was impaired in the IGT and NIDDM groups as demonstrated by pulse analysis, cross-correlation analysis, and spectral analysis; (b) the absolute amplitude of the ISR pulses progressively declined with the transition from obesity to IGT to NIDDM; and (c) the absolute amplitude of the ISR oscillations failed to increase appropriately with increasing absolute amplitude of glucose oscillations in the IGT and NIDDM subjects compared with the control group. In conclusion, the present study demonstrates that important dynamic properties of the feedback loop linking insulin secretion and glucose are disrupted not only in established NIDDM but also in conditions where glucose tolerance is only minimally impaired. Further studies are needed to determine how early in the course of beta-cell dysfunction this lack of control by glucose of the ultradian oscillations in insulin secretion occurs and to define more precisely if this phenomenon plays a pathogenetic role in the onset of hyperglycemia in genetically susceptible individuals.
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Affiliation(s)
- N M O'Meara
- Department of Medicine, University of Chicago, Pritzker School of Medicine, Illinois 60637
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39
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Sturis J, Polonsky KS, Shapiro ET, Blackman JD, O'Meara NM, van Cauter E. Abnormalities in the ultradian oscillations of insulin secretion and glucose levels in type 2 (non-insulin-dependent) diabetic patients. Diabetologia 1992; 35:681-9. [PMID: 1644248 DOI: 10.1007/bf00400263] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To investigate the temporal organization of insulin secretion and glucose concentration during fasting in Type 2 (non-insulin-dependent) diabetes mellitus, we studied seven patients with Type 2 diabetes, eight obese non-diabetic control subjects and eight normal weight non-diabetic subjects. Blood sampling for glucose, insulin and C-peptide was performed at 15-min intervals during a 24-h period of fasting for the diabetic and the obese control subjects and during an 8-h fasting period for the normal subjects. Insulin secretion rates were calculated from the peripheral C-peptide concentration profiles. Ultradian oscillations of glucose levels and insulin secretion rates were evident during fasting in all subjects. An additional study with blood sampling at 2-min intervals for 8 h further indicated that this ultradian periodicity is expressed independently of rapid 10-15 min insulin oscillations. There were no differences between diabetic and non-diabetic subjects in the frequency of the ultradian oscillations of insulin secretion (which averaged 12-15 oscillations per 24 h) and in the rate of concomitancy of oscillations of insulin secretion with oscillations in glucose levels, which averaged 63-65%. The relative amplitudes of both the insulin and glucose oscillations were also similar in diabetic and nondiabetic subjects. The major abnormality in patients with Type 2 diabetes was evidenced by spectral analysis, and confirmed by calculations of the distributions of inter-pulse intervals. It consisted of a slowing of the glucose oscillations, without a similar slowing of the oscillations in insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Sturis
- Department of Medicine, University of Chicago, Illinois
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40
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Van Cauter E, Blackman JD, Roland D, Spire JP, Refetoff S, Polonsky KS. Modulation of glucose regulation and insulin secretion by circadian rhythmicity and sleep. J Clin Invest 1991; 88:934-42. [PMID: 1885778 PMCID: PMC295490 DOI: 10.1172/jci115396] [Citation(s) in RCA: 276] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
To define the roles of circadian rhythmicity (intrinsic effects of time of day independent of the sleep or wake condition) and sleep (intrinsic effects of the sleep condition, irrespective of the time of day) on the 24-h variation in glucose tolerance, eight normal men were studied during constant glucose infusion for a total of 53 h. The period of study included 8 h of nocturnal sleep, 28 h of continuous wakefulness, and 8 h of daytime sleep. Blood samples for the measurement of glucose, insulin, C-peptide, cortisol, and growth hormone were collected at 20-min intervals throughout the entire study. Insulin secretion rates were derived from C-peptide levels by deconvolution. Sleep was polygraphically monitored. During nocturnal sleep, levels of glucose and insulin secretion increased by 31 +/- 5% and 60 +/- 11%, respectively, and returned to baseline in the morning. During sleep deprivation, glucose levels and insulin secretion rose again to reach a maximum at a time corresponding to the beginning of the habitual sleep period. The magnitude of the rise above morning levels averaged 17 +/- 5% for glucose and 49 +/- 8% for calculated insulin secretion. Serum insulin levels did not parallel the circadian variation in insulin secretion, indicating the existence of an approximate 40% increase in insulin clearance during the night. Daytime sleep was associated with a 16 +/- 3% rise in glucose levels, a 55 +/- 7% rise in insulin secretion, and a 39 +/- 5% rise in serum insulin. The diurnal variation in insulin secretion was inversely related to the cortisol rhythm, with a significant correlation of the magnitudes of their morning to evening excursions. Sleep-associated rises in glucose correlated with the amount of concomitant growth hormone secreted. These studies demonstrate previously underappreciated effects of circadian rhythmicity and sleep on glucose levels, insulin secretion, and insulin clearance, and suggest that these effects could be partially mediated by cortisol and growth hormone.
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Affiliation(s)
- E Van Cauter
- Department of Medicine, University of Chicago, Illinois 60637
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41
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Simon C, Brandenberger G, Follenius M, Schlienger JL. Alteration in the temporal organisation of insulin secretion in type 2 (non-insulin-dependent) diabetic patients under continuous enteral nutrition. Diabetologia 1991; 34:435-40. [PMID: 1909248 DOI: 10.1007/bf00403183] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Concomitant oscillations of plasma glucose, insulin and C-peptide levels with a period of about 80 min between peak levels have been identified in normal man. To determine whether these oscillations persist in Type 2 (non-insulin-dependent) diabetic patients, peripheral plasma levels of glucose, insulin and C-peptide were measured at 10 min intervals over 12 h in six patients and in six matched control subjects during continuous enteral nutrition (90 kcal.h-1;50% carbohydrate, 35% fat, 15% protein). The insulin secretion rate was estimated from peripheral C-peptide levels using an open two-compartment model. For the control subjects, mean plasma glucose, insulin and insulin secretion profiles rose sharply and then attained a steady-state; in contrast, for the diabetic patients, the mean insulin and insulin secretion profiles were characterized by a slow ascending trend throughout the day. Mean glucose levels rose sharply and reached higher levels than in the control subjects. The individual 12 h profiles revealed synchronous oscillations of plasma glucose, plasma insulin, and insulin secretion in the control subjects. In the diabetic patients, the number of plasma insulin and insulin secretion pulses was significantly lower; they had a smaller amplitude and were less frequently associated with the glucose pulses. However, plasma glucose levels had a similar oscillatory pattern in the diabetic patients compared with the control subjects, albeit with a higher absolute amplitude. The poor association between glucose and insulin secretion pulses in the diabetic patients suggests that insulin pulses are insufficient to account for the glucose pulses.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C Simon
- Laboratoire de Physiologie et de Psychologie Environnementales, CNRS/INSR, Strasbourg, France
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42
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Sturis J, Van Cauter E, Blackman JD, Polonsky KS. Entrainment of pulsatile insulin secretion by oscillatory glucose infusion. J Clin Invest 1991; 87:439-45. [PMID: 1991830 PMCID: PMC295095 DOI: 10.1172/jci115015] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ultradian "oscillations" or "pulses" of insulin secretion with periods around 120 min occur in man. It is not known whether glucose plays an active role in generating these oscillations, or if an intrapancreatic pacemaker generates oscillations in insulin secretion that entrain glucose passively. To determine if the frequency of pulses of insulin secretion could be modified by oscillatory glucose infusion, seven normal men were studied on three separate occasions. The first study involved a constant glucose infusion administered at a rate of 6 mg/kg per min for 28 h. During the two subsequent studies, the subjects received an oscillatory glucose infusion for 28 h with the same mean rate, an amplitude of 33% above and below the mean infusion rate, a sinusoidal waveshape and a period either 20% longer ("slow oscillatory infusion") or 20% shorter ("rapid oscillatory infusion") than the periodicity observed during constant glucose infusion. Samples for insulin, C-peptide, and glucose were drawn at 10-min intervals during the last 24 h of each study. Insulin secretion rates were calculated by deconvolution of C-peptide levels. During constant glucose infusion, the respective periods of oscillation of glucose and insulin secretion averaged 126 +/- 5 min and 118 +/- 3 min (mean +/- SEM). During the slow oscillatory infusion, the period of infusion was 155 +/- 7 min and the periods of insulin secretion and glucose were, respectively, 155 +/- 7 min and 150 +/- 5 min. During rapid oscillatory infusion, the period of infusion was 103 +/- 5 min and the period of both insulin secretion and glucose was 105 +/- 5 min. Thus the periodicity of both insulin secretion and plasma glucose changed in parallel with the exogenous periodicity, indicating complete entrainment of the secretory oscillations. These results suggest that the ultradian oscillations of insulin secretion are caused by the feedback loop linking glucose and insulin.
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Affiliation(s)
- J Sturis
- Department of Medicine, University of Chicago, Illinois 60637
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43
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Brandenberger G, Krauth MO, Ehrhart J, Libert JP, Simon C, Follenius M. Modulation of episodic renin release during sleep in humans. Hypertension 1990; 15:370-5. [PMID: 2180817 DOI: 10.1161/01.hyp.15.4.370] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We previously described a strong concordance between nocturnal oscillations in plasma renin activity and sleep cycles. To examine whether modifying renal renin content or release influences the response to central stimuli linked to sleep stage alternation, plasma renin activity was measured every 10 minutes from 11:00 PM to 8:00 AM in three groups of six subjects. The first group received one 40 mg dose of the diuretic furosemide; the second group underwent the night experiment after 3 days on a low sodium diet; the third group received one 100 mg dose of the beta-blocker atenolol. Each subject underwent a control night when a placebo was given. The nocturnal curves were analyzed with a pulse detection program. For the control nights, 74 of the 83 sleep cycles were associated with significant plasma renin activity oscillations; non-rapid eye movement sleep occurred in the ascending portions and rapid eye movement sleep in the declining portions of the oscillations. These oscillations persisted in the three groups of subjects during the experimental nights and the relation with the sleep stages was not disturbed. Acute stimulation by furosemide amplified the oscillations and led to a general upward trend of the nocturnal profiles. Similarly, a low sodium diet, which led to a slow increase in renal renin content, provoked large oscillations with high initial levels. However, in both cases the mean relative amplitude of the oscillations, expressed as a percentage of the nocturnal means, was similar to that of the control nights and approximated 60%.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G Brandenberger
- Laboratoire de Physiologie et de Psychologie Environnementales, Strasbourg, France
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