Diurnal Variation Of Plasmatic Melatonin, Corticosterone And Variation Of General Activity In Pigeons Under Light-dark Cycle And Constant Light

This work analyzed the diurnal variation of general activity and plasmatic levels of melatonin and corticosterone in pigeons submitted to a 12:00:12:00h light-dark cycle (lights on at 6:00 a.m.) or to constant light. In both conditions pigeons were observed in 5-min sessions at times 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 and 24:00h during two successive days. Behavior was video taped in the home cages for posterior categorization and quantification. Radioimmunoassays were used to evaluate plasmatic levels of melatonin and corticosterone. Blood samples were obtained at the times of behavioral observation. In the light-dark condition the results showed day-night variation of general activity (p < 0.001) and a robust diurnal rhythm of plasmatic melatonin (p < 0.001). Both of these variations as well as the oscillatory secretion of corticosterone disappeared under constant light condition. The parallel changes in general activity and blunting of melatonin rhythm secretion in constant light condition agree with previous evidences that melatonin may regulate behavioral oscillations in the pigeon. The present data are related to the proposition that the timing system in pigeons may involve neuroendocrine relations characterized by interactions between blood born signalization by melatonin and corticosterone.322243254Adachi, A., Suzuki, Y., Nogi, T., Ebihara, S., Rhythms in the pigeon: Effects of melatonin inhibition on dopamine release (1999) Brain Res, 815, pp. 435-440Aschoff, J., Exogenous and endogenous componentes in circadian rhythms (1960) Cold Spring Habor Symp Quant Biol, 25, pp. 11-28Aschoff, J., Masking of circadian rhythms by Zeitgebers as opposed to entrainment (1987) Trends in Chronobiology, pp. 149-161. , Hekkens W, Kerkhof GH, Rietveld WJ, eds. Pergamon PressBeldhuis, H.J.A., Dittami, J.P., Gwinner, E., Melatonin and the circadian rhythms of feeding and perch-hopping in the European starling, Sturnus vulgaris (1988) J Comp Physiol A, 164, pp. 7-14Binkley, S., Kluth, E., Menaker, M., Pineal function in sparrows: Circadian rhythms and body temperature (1971) Science, 174, pp. 311-314Brainard, C.G., Richardson, B.A., Petterborg, L.J., Reiter, R.J., The effect of different light intensities on pineal melatonin content (1982) Brain Res, 233, pp. 75-81Buijs, R.M., Wortel, J., Van Heerikhuize, J.J., Feenstra, M.G., Ter Horst, G.J., Romijn, H.J., Kalsbeek, A., Anatomical and functional demonstration of a multisynaptic suprachiasmatic nucleus adrenal (cortex) pathway (1999) Eur J Neurosci, 11, pp. 1535-1544Buttemer, W.A., Lee, B., Astheime, R., Wingfield, J.C., The effect of corticosterone on standard metabolic rates in small passerine birds (1991) Comp Physiol B, 161, pp. 427-431Cardinali, D.P., Golombek, D.A., Rosenstein, R.E., Cutrera, R.A., Esquifino, A.I., Melatonin site and mechanism of action: Single or multiple? (1997) J Pineal Res, 32, pp. 32-39Cassone, V.M., Brooks, D.S., Kelm, T.A., Comparative distribution of 2[125I] iodomelatonin binding in the brains of diurnal birds: Outgroup analysis with turtles (1995) Brain Behav Evol, 45, pp. 241-256Cassone, V.M., Forsyth, A.M., Woodlee, G.L., Hypothalamic regulation of circadian noradrenergic input to the chick pineal gland (1990) J Comp Physiol A, 167, pp. 187-192Cassone, V.M., Menaker, M., Is the avian circadian system a neuroendocrine loop? (1984) J Exp Zool, 232, pp. 539-549Cassone, V.M., Moore, R.Y., Retino-hypothalamic projections and suprachiasmatic nucleus of the house sparow, Passer domesticus (1987) J Comp Neurol, 266, pp. 171-182Chabot, C.C., Menaker, M., Environmental and endogenous control of feeding and perch hopping rhythmicity in the house sparrow (1987) Soc Neurosci Abstr, 13, p. 1038Chabot, C.C., Menaker, M., Effects of physiological cycles of infused melatonin on circadian rhythmicity in pigeons (1992) J Comp Physiol A, 170, pp. 615-622Champney, T., Steger, R., Christie, O., Reiter, R., Alterations in components of the pineal melatonin synthetic pathway by acute insuline stress in the rar and Syrian hamster (1985) Brain Res, 338, pp. 25-32Chan, S.W.C., Phillips, J.G., Circadian variation in activity of the duck (Anas platyrhynchos) adrenal gland (1973) Gen Comp Endocrinol, 20, pp. 291-296Ebihara, S., Adachi, A., Hasegawa, M., Yoshimura, T., Hirunagi, K., In vivo microdyalisis studies of pineal and ocular melatonin rhythms in birds (1997) Biol Signals, 6, pp. 233-240Ebihara, S., Kawamura, H., The role of pineal organ and the suprachismatic nucleus in the conrol of circadian locomotor rhythms in the Java sparrow Padda oryzivora (1981) J Comp Physiol, 141, pp. 207-214Ebihara, S., Uchiyama, K., Oshima, I., Circadian organization in the pigeon, Columba livia: The role of the pineal organ and the eye (1984) Comp Physiol A, 154, pp. 59-69Ferrari, E.A.M., Faleiros, L., Cerutti, S.M., Oliveira, A.M., Functional meaning of sound an habituation of exploratory behavior in detelencephalated pigeons (1999) Behav Brain Res, 101, pp. 93-103Foa, A., Menaker, M., Contribution of pineal and retinae to the circadian rhythms of circulating melatonin in pigeons (1988) J Comp Physiol A, 64, pp. 25-30Gaston, S., Menaker, M., Pineal function: A biological clock in sparrows? (1968) Science, 160, pp. 1125-1127Golombek, D.A., Burin, L., Cardinali, D.P., Time-dependency for the effect of different stressors on rat pineal melatonin content (1992) Acta Physio Pharmacol Ther Latinoam, 42, pp. 35-42Gorzalka, B.B., Brotto, L.A., Hong, J.J., Corticosterone regulation of 5-HT2A receptor-mediated behaviors: Attenuation by melatonin (1999) Physiol Behav, 67, pp. 439-442Gwinner, E., Hau, M., Heigl, S., Melatonin: Generation and modulation of avian circaduan rhythms (1997) Brain Research Bulletin, 44, pp. 439-444Joseph, M.M., Meier, A.H., Daily rhythms of plasma corticosterone in the common pigeon, Columba livia (1973) Gen Comp Endocrinol, 20, pp. 326-330Khan, R., Daya, S., Potgieter, B., Evidence for a modulation of the stress response by the pineal gland (1990) Experientia, 46, pp. 860-862Kovacs, K., Péczely, P., Peths, G., Daily fluctuations of peripheral metabolism of corticosterone in male Japanese quails: A dynamic approach to the development of plasma corticosterone daily rhythm (1983) Comp Biochem Physiol, 75 A, pp. 467-469Kumar, V., Follett, B.K., The circadian nature of melatonin secretion in Japanese quail (Coturnix coturnix japonica) (1993) J Pineal Res, 14, pp. 192-200Mahata, S.K., De, K., Effect of melatonin on norepinephrine, epinephrine, and corticosterone contents in the adrenal gland of three avian species (1991) J Comp Physiol B, 161, pp. 81-84Meier, A.H., Fivizanni, A.J., Ottenweller, J.E., Daily rhythms of plasma corticosterone binding activity in the white throated sparrow, Zonotrichia albicollis (1978) Life Sci, 22, pp. 401-406Mess, B., Rekasi, Z., Gosh, M., Csernus, V., Regulation of pineal melatonin secretion: Comparison between mammals and birds (1996) Acta Biol Hung, 47, pp. 313-322Michell, M.A., Macleod, M.G., Raza, A., The effects of ACTH and dexamethazone upon plasma thyroid hormone levels and heat productions in the domestic fowl (1986) Comp Biochem Physiol, 38 A, pp. 207-215Oshima, I., Yamada, H., Goto, M., Sato, K., Ebiraha, S., Pineal and retinal melatonin is involved in the control of circadian locomotor activity and body temperature rhythms in the pigeon (1989) J Comp Physiol A, 166, pp. 217-226Oshima, I., Yamada, H., Sato, K., Ebiraha, S., The phase relationship between the circadian rhythms of locomotor activity and circulating melatonin in the pigeon (Columba livia) (1987) Gen Comp Endocrinol, 67, pp. 409-414Persengiev, S.P., Kanchev, L.N., Melatonin and Adrenal Cortex Steroid production: In Vivo and in vitro studies (1991) Folia Histochemica Et Cytobiologica, 29, pp. 15-18Pevet, P., Jacob, N., Lakhdar-Ghazal, N., Vuillez, P., How do suprachiasmatic nuclei of the hypothalamus integrate photoperiodic informations? (1997) Biol Cell, 89, pp. 569-577Pilo, B., John, T.M., George, J.C., Etches, R.J., Liver Na +K +-ATPase activity and circulating levels of corticosterone and thyroid hormones following cold and heat exposure in the pigeon (1985) Comp Biochem Physiol, 80, pp. 103-106Reiter, R.J., Neuroendocrine effects of light (1991) Int J Biometeorol, 35, pp. 169-175Sanchez de la Pena, S., Halberg, F., Lakatua, D., Ungar, F., Rhythmic pineal-hypohyseal-adrenal intermodulations ex vivo (1987) Prog Clin Biol Res, 227 A, pp. 421-449Silva, A.L., Ferrari, E.A.M., Massive telencephalic lesions and the organization of behavior in pigeons (1991) Braz J Med Biol Res, 24, pp. 509-513Stockgrand, L.T.D., (1984) CIDtech Ultraspecific Melatonin antiserum for Radioimmunoassay, , School of Biological Sciences, Department of Biochemistry, University of SurreyTakahashi, J.S., Menaker, M., Role of the Suprachiasmatic nucleus in the circadian system of the house Sparrow Passes domesticus (1984) J Neurosc, 2, pp. 815-828Takahashi, J.S., Murakami, N., Nikaido, S.S., Pratt, B.L., Robertson, L.M., The avian pineal, a vertebrate model system of the circadian oscillator: Cellular regulation of circadian rhythms by light, second messengers, and macromolecular synthesis (1992) Rec Prog Hormone Res, 45, pp. 279-352Turek, F.W., Circadian rhythms (1994) Recent Progress in Hormone Research, 49, pp. 43-89Van Cauter, E., Aschoff, J., Endocrine and other biological rhythms (1989) Endocrinology, pp. 2658-2705. , De Groot LI, ed. Philadelphia, SaundersVieira, J.G.H., (1977) Radioimunoensaio do cortisol sérico: Metodologia e aplicações clínicas, , Dissertação de Mestrado, Escola Paulista de Medicina, São Paulo, SPWesterhof, I., Mol, J.A., Van Den Brom, W.E., Lumeij, J.T., Rijnberk, A., Diurnal rhythms of plasma corticosterone concentrations in racing Pigeons (Columba livia domestica) exposed to different light regimens, and the influence of frequent blood sampling (1994) Avian Diseases, 38, pp. 428-434Wu, W.T., Chen, Y.C., Reiter, R.J., Day-night differences in the response of the pineal gland to swimming stress (1988) Proc Soc Exp Biol Med, 187, pp. 315-319Yamada, H., Oshima, I., Sato, K., Ebihara, S., Loss of circadian rhythms of locomotor activity, food intake and plasma melatonin concentration induced by constant light in pigeons (Columba livia) (1988) J Comp Physiol A, 163, pp. 459-46

Automated Measurement Of Mouse Freezing Behavior And Its Use For Quantitative Trait Locus Analysis Of Contextual Fear Conditioning In (balb/cj X C57bl/6j)f2 Mice

The most commonly measured mouse behavior in fear conditioning tests is freezing. A technical limitation, particularly for genetic studies, is the method of direct observation used for quantifying this response, with the potential for bias or inconsistencies. We report the use of a computerized method based on latency between photobeam interruption measures as a reliable scoring criterion in mice. The different computer measures obtained during contextual fear conditioning tests showed high correlations with hand-scored freezing; r values ranged from 0.87 to 0.94. Previously reported strain differences between C57BL/6J and DBA/2J in context-dependent fear conditioning were also detected by the computer-based system. In addition, the use of computer-scored freezing of 199 (BALB/cJ x C57BL/6J)F2 mice enabled us to detect a suggestive gender-dependent chromosomal locus for contextual fear conditioning on distal chromosome 8 by QTL analysis. Automation of freeze scoring would significantly increase efficiency and reliability of this learning and memory test.54-5391403Abeliovich, A., Paylor, R., Chen, C., Kim, J.J., Wehner, J.M., Tonegawa, S., PKCγ mutant mice exhibit mild deficits in spatial and contextual learning (1993) Cell, 75, pp. 1263-1271Aiba, A., Chen, C., Herrup, K., Rosenmund, C., Stevens, C.F., Tonegawa, S., Reduced hippocampal long-term potentiation and context-specific deficit in associative learning in mGluR1 mutant mice (1994) Cell, 79, pp. 365-375Ausubel, F.M., Brent, R., Kingston, R.E., Moore, D.D., Seideman, J.G., Smith, J.A., Struhl, K., (1995) Current Protocols in Molecular Biology, , John Wiley and Sons, New York, NYBlanchard, R.D., Blanchard, R.J., Ethoexperimental approaches to the biology of emotions (1988) Annu. Rev. Psychol., 39, pp. 43-68Fanselow, M.S., Factors governing one-trial contextual conditioning (1990) Anim. Learn. Behav., 18, pp. 264-270Graef, F.G., Neuroanatomy and neurotransmitter regulation of defensive behaviors and related emotions in mammals (1994) Braz. J. Med. Biol. Res., 27, pp. 811-829Lander, E.S., Botstein, D., Mapping mendelian factors underlying quantitative traits using RFLP linkage maps (1989) Genetics, 121, pp. 185-19

Ion cyclotron resonance heating for tungsten control in various JET H-mode scenarios

Ion cyclotron resonance heating (ICRH) in the hydrogen minority scheme provides central ion heating and acts favorably on the core tungsten transport. Full wave modeling shows that, at medium power level (4 MW), after collisional redistribution, the ratio of power transferred to the ions and the electrons vary little with the minority (hydrogen) concentration n H/n e but the high-Z impurity screening provided by the fast ions temperature increases with the concentration. The power radiated by tungsten in the core of the JET discharges has been analyzed on a large database covering the 2013-2014 campaign. In the baseline scenario with moderate plasma current (I p = 2.5 MA) ICRH modifies efficiently tungsten transport to avoid its accumulation in the plasma centre and, when the ICRH power is increased, the tungsten radiation peaking evolves as predicted by the neo-classical theory. At higher current (3-4 MA), tungsten accumulation can be only avoided with 5 MW of ICRH power with high gas injection rate. For discharges in the hybrid scenario, the strong initial peaking of the density leads to strong tungsten accumulation. When this initial density peaking is slightly reduced, with an ICRH power in excess of 4 MW,very low tungsten concentration in the core (∼10-5) is maintained for 3 s. MHD activity plays a key role in tungsten transport and modulation of the tungsten radiation during a sawtooth cycle is correlated to the fishbone activity triggered by the fast ion pressure gradient

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium–tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle–energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons

3D simulations of gas puff effects on edge plasma and ICRF coupling in JET

Recent JET (ITER-Like Wall) experiments have shown that the fueling gas puffed from different locations of the vessel can result in different scrape-off layer (SOL) density profiles and therefore different radio frequency (RF) coupling. To reproduce the experimental observations, to understand the associated physics and to optimize the gas puff methods, we have carried out three-dimensional (3D) simulations with the EMC3-EIRENE code in JET-ILW including a realistic description of the vessel geometry and the gas injection modules (GIMs) configuration. Various gas puffing methods have been investigated, in which the location of gas fueling is the only variable parameter. The simulation results are in quantitative agreement with the experimental measurements. They confirm that compared to divertor gas fueling, mid-plane gas puffing increases the SOL density most significantly but locally, while top gas puffing increases it uniformly in toroidal direction but to a lower degree. Moreover, the present analysis corroborates the experimental findings that combined gas puff scenarios - based on distributed main chamber gas puffing - can be effective in increasing the RF coupling for multiple antennas simultaneously. The results indicate that the spreading of the gas, the local ionization and the transport of the ionized gas along the magnetic field lines connecting the local gas cloud in front of the GIMs to the antennas are responsible for the enhanced SOL density and thus the larger RF coupling

Real-time-capable prediction of temperature and density profiles in a tokamak using RAPTOR and a first-principle-based transport model

The RAPTOR code is a control-oriented core plasma profile simulator with various applications in control design and verification, discharge optimization and real-time plasma simulation. To date, RAPTOR was capable of simulating the evolution of poloidal flux and electron temperature using empirical transport models, and required the user to input assumptions on the other profiles and plasma parameters. We present an extension of the code to simulate the temperature evolution of both ions and electrons, as well as the particle density transport. A proof-of-principle neural-network emulation of the quasilinear gyrokinetic QuaLiKiz transport model is coupled to RAPTOR for the calculation of first-principle-based heat and particle turbulent transport. These extended capabilities are demonstrated in a simulation of a JET discharge. The multi-channel simulation requires ∼0.2 s to simulate 1 second of a JET plasma, corresponding to ∼20 energy confinement times, while predicting experimental profiles within the limits of the transport model. The transport model requires no external inputs except for the boundary condition at the top of the H-mode pedestal. This marks the first time that simultaneous, accurate predictions of Te, Tiand nehave been obtained using a first-principle-based transport code that can run in faster-than-real-time for present-day tokamaks

Runaway electron beam control

Post-disruption runaway electron (RE) beams in tokamaks with large current can cause deep melting of the vessel and are one of the major concerns for ITER operations. Consequently, a considerable effort is provided by the scientific community in order to test RE mitigation strategies. We present an overview of the results obtained at FTU and TCV controlling the current and position of RE beams to improve safety and repeatability of mitigation studies such as massive gas (MGI) and shattered pellet injections (SPI). We show that the proposed RE beam controller (REB-C) implemented at FTU and TCV is effective and that current reduction of the beam can be performed via the central solenoid reducing the energy of REs, providing an alternative/parallel mitigation strategy to MGI/SPI. Experimental results show that, meanwhile deuterium pellets injected on a fully formed RE beam are ablated but do not improve RE energy dissipation rate, heavy metals injected by a laser blow off system on low-density flat-top discharges with a high level of RE seeding seem to induce disruptions expelling REs. Instabilities during the RE beam plateau phase have shown to enhance losses of REs, expelled from the beam core. Then, with the aim of triggering instabilities to increase RE losses, an oscillating loop voltage has been tested on RE beam plateau phase at TCV revealing, for the first time, what seems to be a full conversion from runaway to ohmic current. We finally report progresses in the design of control strategies at JET in view of the incoming SPI mitigation experiments