1,721,088 research outputs found
Intracerebroventricular injection of prostaglandin E(1) changes concentrations of biogenic amines in the posterior hypothalamus of the rat.
No full textSince the posterior hypothalamus (PH) plays a key role in the control of body temperature, the aim of this study was to evaluate the changes in adrenaline, noradrenaline and dopamine levels in the PH during the hyperthermia induced by prostaglandin E(1) (PGE(1)). The concentration of adrenaline, noradrenaline and dopamine in the PH, the firing rate of the sympathetic nerves innervating interscapular brown adipose tissue (IBAT), IBAT and colonic temperatures (T(IBAT) and T(C)) were monitored in 12 urethane-anaesthetized male Sprague-Dawley rats before and after an intracerebroventricular injection of 500 ng PGE(1) dissolved in 2 microl of 0.9\% NaCl saline solution or only saline. The catecholamines were collected using a microdialysis probe and quantified by HPLC. The results showed that PGE(1) caused a significant increment in the concentration of adrenaline from 15. 83+/-2.69 to 34.95+/-3.9 ng ml(-1) and of dopamine from 35.15+/-4.48 to 55.68+/-6.21 ng ml(-1). A significant decrease in the level of noradrenaline from 18.75+/-2.05 to 8.56+/-2.26 ng ml(-1) was registered. The firing rate of sympathetic nerves to IBAT was increased from 100+/-0\% to 204.83+/-15.22\% by PGE(1). T(IBAT) and T(C) rose respectively from 36.91+/-0.15 degrees C to 38.88+/-0.29 degrees C, and from 36.7+/-0.15 degrees C to 38.13+/-0.36 degrees C after the injection of PGE(1). The changes in adrenaline and noradrenaline occurred during the first 20 min as did the changes in temperature and firing rate, while the change in dopamine was delayed until 21-60 min after the PGE(1) injection. No significant change of analyzed variables was found in the control rats. These findings suggest that these biogenic amines of the PH are involved in the control of the sympathetic and thermogenic changes induced by PGE(1)
Functional decortication lowers ventromedial hypothalamic activation induced by hippocampal neostigmine injection.
No full textThis experiment tested the effects of cortical spreading depression (CSD) on the ventromedial hypothalamic activity and on the related thermogenesis, both stimulated by an injection of neostigmine in the hippocampus. The firing rate of the neurons of the ventromedial hypothalamus, and the temperature of the interscapular brown adipose tissue and of the colon (T:(IBAT) and T:(C)) were monitored in 24 urethane-anesthetized male Sprague-Dawley rats divided into four groups. These variables were measured before and after hippocampal injection of neostigmine (5 x 10(-7) mol) in the first and second groups or of saline in the third and fourth groups. The hippocampal injection was preceded by CSD in the first and third groups, while CSD was not induced in the second and fourth groups. The same procedure was carried out in the other four groups of six rats each and oxygen consumption was monitored. The results show an increase in the firing rate, T:(IBAT), T:(C) and oxygen consumption after the neostigmine injection. CSD significantly reduces these enhancements. The findings demonstrate that: (i) the activation of ventromedial hypothalamic neurons are involved in the thermogenic changes due to the effects of a neostigmine injection into the hippocampus; and (ii) integrity of cerebral cortex is required for this activation of thermogenesis
Administration of muscimol into the posterior hypothalamus reduces hyperthermia induced by hippocampal neostigmine injection.
No full textThe firing rate of the sympathetic nerves innervating interscapular brown adipose tissue (IBAT), IBAT and colonic temperatures (T(IBAT) and T(C)) and oxygen (O(2)) consumption were monitored in urethane-anesthetized male Sprague-Dawley rats. These variables were measured for 40 min before (baseline values) and 40 min after an injection of neostigmine (5 x 10(-7) mol in 1 microl of saline) into the hippocampus and a bilateral administration of a GABA(a)-agonist, muscimol (28 ng in 0.5 microl of saline, per side) into the posterior hypothalamus. The same variables were recorded in other rats, but the muscimol was replaced by saline. Control animals were used with muscimol or saline alone. The results show an increase of sympathetic firing rate, T(IBAT), T(C) and O(2) consumption after neostigmine injection. Muscimol significantly reduces this enhancement. The findings suggest that hippocampus controls the sympathetic and thermogenic activation induced by neostigmine through an influence on GABAergic tone of the posterior hypothalamus
Paradoxical [correction of parodoxical] effect of orexin A: hypophagia induced by hyperthermia.
No full textThis experiment tested the effect of the sympathetic and thermogenic activation induced by orexin A on eating behavior. The food intake, firing rate (FR) of the sympathetic nerves to interscapular brown adipose tissue (IBAT), IBAT and abdominal temperatures (T(IBAT) and T(ab)), and heart rate (HR) were monitored in 24 h-fasting male Sprague-Dawley rats for 15 h after food presentation. Orexin A (1.5 nmol) was injected into the lateral cerebral ventricle 6 h before food presentation while FR, T(IBAT) and T(ab), and HR were also monitored. The same variables were controlled in rats receiving orexin A contemporaneously to food presentation. Two other groups of control animals were tested with the same procedure, however orexin A was substituted by saline. The results showed that food intake was significantly lower in the group receiving orexin A 6 h before food presentation in comparison to all the other groups. FR, T(IBAT) and T(ab), and HR were significantly higher in the rats receiving orexin A with respect to rats receiving saline. These findings demonstrate that orexin A, so-called for its orexigen action, can also induce hypophagia. On the other hand, orexin A always induces an activation of the thermogenesis. These results suggest a revision of the role played by orexin A in the control of food intake, assigning to this peptide a primary role in the thermoregulation. The possibility that orexin A can induce hypophagia is well demonstrated by this experiment, so that the scientific community should use a different name for this peptide. An appropriate name could be 'hyperthermine' A
Haloperidol reduces the sympathetic and thermogenic activation induced by orexin A.
No full textThis experiment tested the effect of haloperidol on the sympathetic and thermogenic effects induced by orexin A. The firing rates of the sympathetic nerves to interscapular brown adipose tissue (IBAT), along with IBAT and colonic temperatures and heart rate were monitored in urethane-anesthetized male Sprague-Dawley rats before and 5 h after an injection of orexin A (1.5 nmol) into the lateral cerebral ventricle. The same variables were monitored in rats with an intraperitoneal administration of haloperidol (1 mg/kg bw), a D(2) receptor antagonist. The results show that orexin A increases the sympathetic firing rate, IBAT and colonic temperatures and heart rate. This increase is reduced by the haloperidol. These findings suggest that dopaminergic system is activated during the orexin A-induced hyperthermia
An aversive diet as thiamine-free food blocks food-induced release of excitatory amino acids in the accumbens.
No full textAs the nucleus accumbens shell plays an important role in the control of eating behaviour, the aim of this study was to evaluate the changes in: (a) the level of aspartic and glutamic acids in the accumbens shell of conditioned rats after the presentation of an aversive diet containing thiamine-free food; (b) the temperature of interscapular brown adipose tissue, effector of thermogenesis related to food intake.The concentration of aspartic and glutamic acids in the accumbens shell, and brown adipose tissue temperature were monitored in conditioned male Sprague-Dawley rats before and after the presentation of thiamine-free food or standard laboratory food. The aspartic and glutamic acids were collected using a microdialysis probe and quantified by HPLC. Food intake was also measured.The results indicated that an intake of standard laboratory food induced an increase in the level of aspartic and glutamic acids, and an elevation in temperature of brown adipose tissue; whereas an intake of thiamine-free food blocks these increases in the conditioned animals.The thiamine-free diet modifies the release of excitatory amino acids in the nucleus accumbens of conditioned animals. This diet also affects thermogenesis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Inhibition of prostaglandin synthesis reduces hyperthermic reactions induced by hypocretin-1/orexin A.
No full textThis experiment tested (i) the effect of orexin A injected into a lateral cerebral ventricle on sympathetic and thermogenic activity and (ii) the involvement of prostaglandins in these phenomena. The firing rates of the sympathetic nerves to interscapular brown adipose tissue (IBAT), along with IBAT and colonic temperatures and heart rate were monitored in urethane-anesthetized male Sprague-Dawley rats before and 6 h after an injection of orexin A (1.5 nmol) into the lateral cerebral ventricle. The same variables were monitored in rats with an intraperitoneal administration of lysine acetylsalicylate (100 mg/kg bw), an inhibitor of prostaglandins synthesis. The results show that orexin A increases the sympathetic firing rate, IBAT and colonic temperatures and heart rate. This increase is reduced by lysine acetylsalicylate. These findings suggest that orexin A affects sympathetic activity, which controls body temperature. Prostaglandins are involved in this control
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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