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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Small volume intravenous infusions of hypertonic saline (HTS) increase blood pressure, heart rate, adrenocorticotropic hormone (ACTH), and cortisol by mechanisms that are not fully understood. We hypothesized that HTS infusions increase prostaglandin biosynthesis and that a prostaglandin synthase metabolite is responsible for mediating actions of HTS. We further hypothesized that thromboxane A2 (TxA2) is the specific metabolite responsible for mediating responses to HTS infusion. Adult female sheep (n=8) were chronically instrumented with vascular catheters and infused intravenously with 7.5% saline at a rate of 4 mL x kg(-1) over 5 min with or without pretreatment with the prostaglandin synthase inhibitor flunixin. Blood pressure, ACTH, and cortisol increased in response to HTS, and these responses were prevented by flunixin. Heart rate increased in response to HTS infusion, and flunixin reduced but did not prevent a heart rate response. Hematocrit decreased significantly in response to HTS but only following flunixin treatment. Arginine vasopressin increased but only modestly in response to HTS, and responses were not different following flunixin. Arterial pH, partial pressure of CO2, and partial pressure of O2 did not change. Circulating concentrations of thromboxane B2, a stable metabolite of TxA2 and an index of TxA2 formation, remained low and did not change in response to HTS. We conclude that heart rate, blood pressure, ACTH, and cortisol responses to HTS are mediated at least in part by a product of prostaglandin synthase metabolism. These responses were not due to increases in circulating concentrations of TxA2 but might involve local formation of TxA2 or some other prostaglandin synthase metabolite.
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PMID:Cardiovascular, adrenocorticotropin, and cortisol responses to hypertonic saline in euvolemic sheep are altered by prostaglandin synthase inhibition. 968 88

General anaesthesia with 80% CO2/20% O2 and 5% halothane in O2 (mask induction) was compared for castration of 3-4 week-old piglets. One group was castrated without anaesthesia. Of the noncastrated control groups one had CO2- and one halothane anaesthesia, one breathed room air through the induction system, and one was held in castration position. The behaviour to induction and castration was assessed, and the cortisol-, ACTH- and beta-endorphin plasma concentrations were determined to quantify the stress elicited by anaesthesia, castration and handling. Violent struggling and vocalization were elicited by CO2 and positioning into the mask induction system while breathing room air; halothane induction was quiet. CO2 induced profound surgical anaesthesia; whereas under halothane anaesthesia some animals exhibited still a slight reaction to castration. Recovery was fast, smooth and quite. Permanent violent struggling and vocalization were elicited by castration without anaesthesia. Plasma cortisol was not a sensitive tool to judge castration stress. The high ACTH and beta-endorphin plasma concentrations elicited by CO2 anaesthesia confirm our clinical experience. General anaesthesia is fast and safely induced with CO2 in piglets and castration can be performed without any reaction, but with CO2 anaesthesia the stress is not reduced.
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PMID:Inhalation anaesthesia for the castration of piglets: CO2 compared to halothane. 992 45

The amount of beta-endorphin-like immunoreactivity (beta-END-LI) in porcine corpora lutea from several stages of the oestrous cycle and the effects of progesterone, oxytocin, and prolactin on beta-END-LI secretion in vitro by luteal cells were studied. Porcine corpora lutea obtained on days 1-5, 6-10, 11-13, 14-18, and 19-21 of the cycle were used to prepare extracts for beta-END-LI determination. Additionally, corpora lutea from days 11-13 and 14-18 were enzymatically dissociated and isolated luteal cells were used for further study of beta-endorphin secretion in vitro. Cells were cultured in serum-free defined M 199 medium (106 cells/ml) at 37 degrees C under 5% CO2 in air, for 12 h. The influences of the following factors on beta-END-LI secretion by luteal cells were tested: progesterone (10-9, 10-7 and 10-5 M), oxytocin (0.01, 0.1, 1 and 10 ng/ml), and prolactin (0.1, 1, 10 and 100 ng/ml). The beta-END-LI contents in extracts and media were measured by radioimmunoassay. The tissue concentration of beta-END-LI was lowest on days 1-5 of the cycle (0.35 +/- 0.03 ng/g wet tissue). Subsequently, it constantly increased to the highest value on days 14-18 (16.58 +/- 0.52 ng/g wet tissue) and on days 19-21 it declined (11.10 +/- 0.52 ng/g wet tissue). Progesterone at a low dose (10-9 M) resulted in significant (p < 0.05) increases and decreases in beta-END-LI secretion by luteal cells from days 11-13 and 14-18, respectively. Higher doses of progesterone (10-7 and 10-5 M) had no effect on beta-END-LI release, compared with the control group. All dose-levels of oxytocin used decreased beta-END-LI secretion by luteal cells on days 11-13 and 14-18 of the cycle. Prolactin at doses of 0.1 and 1 ng/ml on days 11-13, and all doses tested on days 14-18 resulted in decreases in beta-END-LI release from luteal cells. These results document evident changes in beta-END-LI content in the pig corpus luteum during its development and indicate the potential roles of progesterone, oxytocin, and prolactin in luteal cell secretion of beta-END-LI.
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PMID:The content of beta-endorphin-like immunoreactivity in porcine corpus luteum and the potential roles of progesterone, oxytocin and prolactin in the regulation of beta-endorphin release from luteal cells in vitro. 1132 64

Corticotropin releasing hormone (CRH) acts on the central nervous system to alter energy balance and influence both food intake and sympathetically-mediated thermogenesis. CRH is also reported to inhibit food intake in several models of hyperphagia including neuropeptide Y (NPY)-induced eating. The recently identified CRH-related peptide, urocortin (UCN), also binds with high affinity to CRH receptor subtypes and decreases food intake in food-deprived and non-deprived rats. The present experiment characterized further the feeding and metabolic effects of UCN by examining its impact after direct injections into the paraventricular nucleus (PVN) of the hypothalamus. In feeding tests (n=8), UCN (50-200 pmol) was injected into the PVN at the onset of the dark cycle and food intake was measured 1, 2 and 4 h postinjection. In separate rats (n=8), the metabolic effects of UCN were monitored using an open circuit calorimeter which measured oxygen consumption (V(O2)) and carbon dioxide production (V(CO2)). Respiratory quotient (RQ) was calculated as V(CO2)/V(O2). UCN suppressed feeding at all times studied and reliably decreased RQ within 30 min of infusion. Additional work examined the effect of UCN (50-100 pmol) pretreatment on the feeding and metabolic effects of NPY. NPY, injected at the start of the dark period, reliably increased 2 h food intake. This effect was blocked by PVN UCN administration. Similarly, UCN blocked the increase in RQ elicited by NPY alone. These results suggest that UCN-sensitive mechanisms within the PVN may modulate food intake and energy substrate utilization, possibly through an interaction with hypothalamic NPY.
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PMID:Hypothalamic paraventricular nucleus injections of urocortin alter food intake and respiratory quotient. 1159 9

In order to provide a methodological demonstration for the study of C cycle in forest, the CENTURY model was applied to simulate the C cycle in Larix gmelinii forest and to approach the impact of global change on it. The results showed that the Larix gmelinii forest served as a C sink, with an annual net absorption of 2.65t.hm-2. Climate change and increased atmospheric CO2 concentration benefited for the net primary production (CNPP) and net C absorption capacity of forests in North China. When the atmospheric temperature was increased by 2 degrees C, the gross biomass and NPP of Larix gmelinii forest increased, while soil C content decreased, and the variation of these three indices was bigger when the precipitation was decreased by 20% than increased by 20%, indicating that the limiting factor for the forest growth in this area is atmospheric temperature, while precipitation is abundant or even too much.
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PMID:[Carbon equilibrium in Larix gmelinii forest and impact of global change on it]. 1175 65

In this paper, we review some critical issues regarding carbon cycling in Amazonia, as revealed by several studies conducted in the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA). We evaluate both the contribution of this magnificent biome for the global net primary productivity/net ecosystem exchange (NPP/NEE) and the feedbacks of climate change on the dynamics of Amazonia. In order to place Amazonia in a global perspective and make the carbon flux obtained through the LBA project comparable with global carbon budgets, we extrapolated NPP/NEE values found by LBA studies to the entire area of the Brazilian Amazon covered by rainforest. The carbon emissions due to land use changes for the tropical regions of the world produced values from 0.96 to 2.4 Pg C year(-1), while atmospheric CO2 inversion models have recently indicated that tropical lands in the Americas could be exchanging a net 0.62+/-1.15 Pg C year(-1) with the atmosphere. The difference calculated from these two methods would imply a local sink of approximately 1.6-1.7 Pg C year(-1), or a source of 0.85 ton C ha(-1) year(-1). Using our crude extrapolation of LBA values for the Amazon forests (5 million km2) we estimate a range for the C flux in the region of -3.0 to 0.75 Pg C year(-1). The exercise here does not account for environmental variability across the region, but it is an important driver for present and future studies linking local process (i.e. nutrient availability, photosynthetic capacity, and so forth) to global and regional dynamic approaches.
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PMID:Amazonia and the modern carbon cycle: lessons learned. 1580 Jul 45

Rising atmospheric [CO2] has the potential to alter soil carbon (C) cycling by increasing the content of recalcitrant constituents in plant litter, thereby decreasing rates of decomposition. Because fine root turnover constitutes a large fraction of annual NPP, changes in fine root decomposition are especially important. These responses will likely be affected by soil resource availability and the life history characteristics of the dominant tree species. We evaluated the effects of elevated atmospheric [CO2] and soil resource availability on the production and chemistry, mycorrhizal colonization, and decomposition of fine roots in an early- and late-successional tree species that are economically and ecologically important in north temperate forests. Open-top chambers were used to expose young trembling aspen (Populus tremuloides) and sugar maple (Acer saccharum) trees to ambient (36 Pa) and elevated (56 Pa) atmospheric CO2. Soil resource availability was composed of two treatments that bracketed the range found in the Upper Lake States, USA. After 2.5 years of growth, sugar maple had greater fine root standing crop due to relatively greater allocation to fine roots (30% of total root biomass) relative to aspen (7% total root biomass). Relative to the low soil resources treatment, aspen fine root biomass increased 76% with increased soil resource availability, but only under elevated [CO2]. Sugar maple fine root biomass increased 26% with increased soil resource availability (relative to the low soil resources treatment), and showed little response to elevated [CO2]. Concentrations of N and soluble phenolics, and C/N ratio in roots were similar for the two species, but aspen had slightly higher lignin and lower condensed tannins contents compared to sugar maple. As predicted by source-sink models of carbon allocation, pooled constituents (C/N ratio, soluble phenolics) increased in response to increased relative carbon availability (elevated [CO2]/low soil resource availability), however, biosynthetically distinct compounds (lignin, starch, condensed tannins) did not always respond as predicted. We found that mycorrhizal colonization of fine roots was not strongly affected by atmospheric [CO2] or soil resource availability, as indicated by root ergosterol contents. Overall, absolute changes in root chemical composition in response to increases in C and soil resource availability were small and had no effect on soil fungal biomass or specific rates of fine root decomposition. We conclude that root contributions to soil carbon cycling will mainly be influenced by fine root production and turnover responses to rising atmospheric [CO2], rather than changes in substrate chemistry.
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PMID:Fine root chemistry and decomposition in model communities of north-temperate tree species show little response to elevated atmospheric CO2 and varying soil resource availability. 1604 14

Corticotropin releasing factor, acting at hypothalamic corticotropin releasing factor receptors, contributes to the neural signaling pathways mediating stress-related responses, as well as those involved in maintaining energy balance homeostasis. Sympathetically-regulated lipid metabolism and heat production in brown adipose tissue contributes to the non-shivering thermogenic component of stress-evoked hyperthermia and to energy expenditure aspects of body weight regulation. To identify potential central pathways through which hypothalamic corticotropin releasing factor influences brown adipose tissue thermogenesis, corticotropin releasing factor was microinjected into the lateral ventricle (i.c.v.) or into hypothalamic sites while recording sympathetic outflow to brown adipose tissue, brown adipose tissue temperature, expired CO2, heart rate and arterial pressure in urethane/chloralose-anesthetized, artificially-ventilated rats. I.c.v. corticotropin releasing factor or corticotropin releasing factor microinjection into the preoptic area or the dorsomedial hypothalamus, but not the paraventricular nucleus of the hypothalamus, elicited sustained increases in brown adipose tissue sympathetic nerve activity, brown adipose tissue temperature, expired CO2 and heart rate. These sympathetic responses to i.c.v. corticotropin releasing factor were eliminated by inhibition of neuronal activity in the dorsomedial hypothalamus or in the raphe pallidus, a putative site of sympathetic premotor neurons for brown adipose tissue, and were markedly reduced by microinjection of ionotropic glutamate receptor antagonists into the dorsomedial hypothalamus. The increases in brown adipose tissue sympathetic outflow, brown adipose tissue temperature and heart rate elicited from corticotropin releasing factor into the preoptic area were reversed by inhibition of neuronal discharge in dorsomedial hypothalamus. These data indicate that corticotropin releasing factor release within the preoptic area activates a sympathoexcitatory pathway to brown adipose tissue and to the heart, perhaps similar to that activated by increased prostaglandin production in the preoptic area, that includes neurons in the dorsomedial hypothalamus and in the raphe pallidus.
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PMID:Corticotropin releasing factor increases in brown adipose tissue thermogenesis and heart rate through dorsomedial hypothalamus and medullary raphe pallidus. 1658 Jan 42

Two trials were conducted to study the effects of continuous infusion of adrenocorticotropic hormone (ACTH) on acid-base balance in broiler chickens. Osmotic pumps delivered 8 IU of ACTH in saline/kg of BW/d for 7 d or the same saline volume as used in ACTH at 1 microL/h for 7 d. Blood samples were taken on d 0 (baseline values) and on d 4, 7, and 14 after onset of the infusions. The ACTH treatment increased the hematocrit, partial pressure of CO2, anion gap, corticosterone, mean corpuscular hemoglobin concentration, the blood concentrations of hemoglobin and HCO3-, and reduced the partial pressure of O2, plasma concentrations of Na+, K+, and Cl-. Blood pH values and plasma concentrations of Ca2+ were unaffected by ACTH treatment. The ACTH infusion also resulted in a significant increase in plasma glucose, cholesterone, high-density lipoprotein, and triglyceride. There were no differences in any of the blood constituents measured from control groups. Results indicate that infusion of ACTH resulted in changes in plasma acid-base status along with changes in other blood metabolic variables. However, the ACTH treatment did not prevent homeostatic regulation of acid-base balance, as indicated by constant blood pH. There was, however, an increased need for O2 to support gluconeogenic energy production; the birds responded by increased erythropoiesis. This adaptive response provided greater numbers of erythrocytes and thus a higher amount of circulating hemoglobin to deliver O2 for metabolism.
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PMID:Stress and acid-base balance in chickens. 1683 Aug 68

We compiled, measured and simulated estimates of NPP and NBP for Amazonian tropical, European temperate, and Siberian Boreal forests from intensive stand-scale field studies, extensive forest biomass inventories, regional atmospheric inversions, and global ecosystem models. We analysed the random and systematic sources of uncertainties pertaining to each approach when comparing their results, and showed that estimates of NPP from different data streams are robustly comparable within their errors. Although NPP increases by a factor of four between Siberia and the Amazon, NBP is larger in Europe than elsewhere, demonstrating that carbon sequestration does not correlate with NPP. We analysed the NPP:NBP ratios in terms of the role of CO2 fertilization. Our results show that the tropical forest NBP carbon sink can be entirely explained by a CO2-induced enhancement of NPP, whereas such a mechanism can only account for 10% of the European sink and up to 50% of Siberian sink. Europe and Siberia are the two regions where factors other than CO, are likely to be dominant in controlling the sequestration of carbon by forest ecosystems, such as management practice, climate, nitrogen deposition, and variation in disturbance regimes.
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PMID:The potential for rising CO2 to account for the observed uptake of carbon by tropical, temperate, and boreal forest biomes. 1763 34


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