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Long-Term Modulation (long-term + modulation)
Selected AbstractsLong-Term Modulation By Postnatal Oxytocin of the ,2 -Adrenoceptor Agonist Binding Sites in Central Autonomic Regions and the Role of Prenatal StressJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2004Z. Díaz-Cabiale Abstract The aim of this work was to evaluate whether oxytocin administered in male rats subcutaneously early in life in the absence or presence of food restriction during pregnancy has life-long effects on the ,2 -agonist binding sites in the nucleus of the solitarii tract (NTS), in the hypothalamus and the amygdala, as evaluated by quantitative receptor autoradiography. Maternal food restriction alone increased the affinity of the ,2 -agonist [3H]UK14.304 binding sites exclusively in the NTS. In offspring from ad libitum fed dams, oxytocin treatment significantly increased the density of ,2 -agonist binding sites in the NTS and in the hypothalamus. The Kd value of the ,2 -agonist binding sites in the hypothalamus of these rats, but not in the other regions studied, was also significantly increased. In offspring from food-restricted dams, oxytocin treatment produced a significant increase of the Bmax values in the hypothalamus and the amygdala and the Kd value of the ,2 -agonist binding sites in the NTS of these rats also was selectively and significantly increased. These results suggest that a postnatal, oxytocin-induced increase of regional ,2 -adrenoceptor function can be seen in adulthood by a persistent, regionally selective increase in the density of central ,2 -adrenoceptor agonist binding sites, in the absence of an affinity change in the NTS. Such a regional increase of ,2 -adrenoceptor signalling in adulthood may contribute to the anti-stress action of postnatal oxytocin. By contrast, after prenatal stress, the potential increase in ,2 -adrenoceptor signalling takes place via selective increases of density with no changes of affinity of the ,2 -agonist binding sites in the hypothalamus and the amygdala. [source] Formalin-Induced Short- and Long-Term Modulation of Cav Currents Expressed in Xenopus Oocytes: An In Vitro Cellular Model for Formalin-Induced PainBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2010Senthilkumar Rajagopal Cav channels were expressed with ,1,1b and ,2, sub-units and the currents (IBa) were studied by voltage clamp. None of the oocytes was dead during the exposure to formalin. Oocyte death was significant between day 1 and day 5 after the exposure to formalin and was uniform among the oocytes expressing various Cav channels. Peak IBa of all Cav and A1, the inactivating current component was decreased whereas the non-inactivated R current was not affected by 5 min. exposure to formalin. On day 1 after the exposure to formalin, Cav1.2c currents were increased, 2.1 and 2.2 currents were decreased and 2.3 currents were unaltered. On day 5, both peak IBa and A1 currents were increased. Cav1.2c, 2.2 and 2.3 currents were increased and Cav2.1 was unaltered on day 10 after the exposure to formalin. Protein kinase C (PKC) may be involved in formalin-induced increase in Cav currents due to the (i) requirement for Cav,1b sub-units; (ii) decreased phorbol-12-myristate,13-acetate potentiation of Cav2.3 currents; (iii) absence of potentiation of Cav2.3 currents following down-regulation of PKC; and (iv) absence of potentiation of Cav2.2 or 2.3 currents with Ser,Ala mutation of Cav,12.2 or 2.3 sub-units. Increased Cav currents and PKC activation may coincide with changes observed in in vivo pain investigations, and oocytes incubated with formalin may serve as an in vitro model for some cellular mechanisms of pain. [source] Long-term modulation of glucose utilization by IL-1, and TNF-, in astrocytes: Na+ pump activity as a potential target via distinct signaling mechanismsGLIA, Issue 1 2002Céline Véga Abstract Interleukin-1, (IL-1,) and tumor necrosis factor-, (TNF-,) markedly stimulate glucose utilization in primary cultures of mouse cortical astrocytes. The mechanism that gives rise to this effect, which takes place several hours after application of cytokine, has remained unclear. Experiments were conducted to identify the major signaling cascades involved in the metabolic action of cytokine. First, the selective IL-1 receptor antagonist (IL-1ra) prevents the effect of IL-1, on glucose utilization in a concentration-dependent manner, whereas it has no effect on the action of TNF-,. Then, using inhibitors of three classical signaling cascades known to be activated by cytokines, it appears that the PI3 kinase is essential for the effect of both IL-1, and TNF-,, whereas the action of IL-1, also requires activation of the MAP kinase pathway. Participation of a phospholipase C-dependent pathway does not appear critical for both IL-1, and TNF-,. Inhibition of NO synthase by L-NAME did not prevent the metabolic response to both IL-1, and TNF-,, indicating that nitric oxide is probably not involved. In contrast, the Na+/K+ ATPase inhibitor ouabain prevents the IL-1,- and TNF-,-stimulated 2-deoxyglucose (2DG) uptake. When treatment of astrocytes with a cytokine was followed 24 h later by an acute application of glutamate, a synergistic enhancement in glucose utilization was observed. This effect was greatly reduced by ouabain. These data suggest that Na+ pump activity is a common target for both the long-term metabolic action of cytokines promoted by the activation of distinct signaling pathways and the enhanced metabolic response to glutamate. GLIA 39:10,18, 2002. © 2002 Wiley-Liss, Inc. [source] Why are the continents just so,?JOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2010M. SANDIFORD Abstract Variations in gravitational potential energy contribute to the intraplate stress field thereby providing the means by which lithospheric density structure is communicated at the plate scale. In this light, the near equivalence in the gravitational potential energy of typical continental lithosphere with the mid-ocean ridges is particularly intriguing. Assuming this equivalence is not simply a chance outcome of continental growth, it then probably involves long-term modulation of the density configuration of the continents via stress regimes that are able to induce significant strains over geological time. Following this notion, this work explores the possibility that the emergence of a chemically, thermally and mechanically structured continental lithosphere reflects a set of thermally sensitive feedback mechanisms in response to Wilson cycle oscillatory forcing about an ambient stress state set by the mid-ocean ridge system. Such a hypothesis requires the continents are weak enough to sustain long-term (108 years) strain rates of the order of ,10,17 s,1 as suggested by observations that continental lithosphere is almost everywhere critically stressed, by estimates of seismogenic strain rates in stable continental interiors such as Australia and by the low-temperature thermochronological record of the continents that requires significant relief generation on the 108 year time-scale. Furthermore, this notion provides a mechanism that helps explain interpretations of recently published heat flow data that imply the distribution of heat-producing elements within the continents may be tuned to produce a characteristic thermal regime at Moho depths. [source] Short- and long-term modulation of the lutein epoxide and violaxanthin cycles in two species of the Lauraceae: sweet bay laurel (Laurus nobilis L.) and avocado (Persea americana Mill.)PLANT BIOLOGY, Issue 3 2008R. Esteban Abstract Short- and long-term responses of the violaxanthin (V) and lutein epoxide (Lx) cycles were studied in two species of Lauraceae: sweet bay laurel (Laurus nobilis L.) and avocado (Persea americana L.). The Lx content exceeded the V content in shade leaves of both species. Both Lx and V were de-epoxidised on illumination, but only V was fully restored by epoxidation in low light. Violaxanthin was preferentially de-epoxidised in low light in L. nobilis. This suggests that Lx accumulates with leaf ageing, partly because its conversion to lutein is limited in shade. After exposure to strong light, shade leaves of avocado readjusted the total pools of ,- and ,-xanthophyll cycles by de novo synthesis of antheraxanthin, zeaxanthin and lutein. This occurred in parallel with a sustained depression of Fv/Fm. In Persea indica, a closely related but low Lx species, Fv/Fm recovered faster after a similar light treatment, suggesting the involvement of the Lx cycle in sustained energy dissipation. Furthermore, the seasonal correlation between non-reversible Lx and V photoconversions and pre-dawn Fv/Fm in sun leaves of sweet bay supported the conclusion that the Lx cycle is involved in a slowly reversible downregulation of photosynthesis analogous to the V cycle. [source] | |||||||||||||