1,720,958 research outputs found
Environment-specific reinstatement of amphetamine-mediated hyperdipsia by morphine and (-)-norpseudoephedrine.
No full textIn a study designed to determine whether environmental and pharmacological stimuli have the ability to take control of amphetamine-mediated hyperdipsia, rats were injected with d,l-amphetamine (AMPH; 4 mg/kg, IP) alone or in combination with (-)-norpseudoephedrine (NPE; 10 mg/kg, IP) and then returned to the home cage or transferred to a distinct environment (test cage). Water intake was measured hourly for 3 h, in the absence of food. AMPH treatment lasted for 10 days, followed by a 6-day extinction phase during which AMPH, but not NPE, injections were discontinued. Subsequently, all animals received challenge injections: NPE (10 mg/kg) on day 17; AMPH (4 mg/kg) on day 19; and morphine (MOR; 1 mg/kg) on day 21. AMPH-mediated hyperdipsia developed in 50% of animals and had an early onset in the home cage. NPE prevented the AMPH effects. Discontinuation of AMPH treatment promptly normalized drinking in the home cage but increased it further in the test cage. Within 6 days of AMPH discontinuation, hyperdipsia completely disappeared. It was reinstated, in the test cage alone, by a challenge injection of NPE or MOR. We suggest that hyperdipsia is a primary AMPH effect, which in some way is counter-acted by a distinct environment. This appears to elicit a compensatory mechanism that is revealed in the absence of AMPH and is reinstated in a nonspecific way by pharmacological stimul
Amphetamine reinstates polydipsia induced by chronic exposure to quinpirole, a dopaminergic D2 agonist, in rats
No full textThe hypothesis that the combined activation of D-1 and D-2 dopaminergic receptors is instrumental in inducing amphetamine (AMPH)-mediated hyperdipsia was tested in rats. The D-1 agonist SKF-38393 (SKF) and the D-2 agonist quinpirole (QNP) were ip injected, alone or in combination. to male rats for 10 days. After 2 days of wash-out, a single dose of AMPH (3 mg/kg) was administered. Intake of water and food and diuresis were daily measured at 2, 5 and 24 h. In two further experiments the higher dose of QNP (0.56 mg/kg) was given with two different doses of the D-1 antagonist SCH-23390 (SCH), or, respectively, of the peripheral D-2 antagonist domperidone (DMP). In a fourth experiment, the possibility that QNP, given alone or in combination with SKF, produces an AMPH-like internal state was evaluated by using a drug-discrimination paradigm. Results show that chronic administration of QNP produced a significant increase of 24 h water intake that was reinstated by AMPH. This QNP effect was only partially prevented by DMP, suggesting a main central mechanism of action. By itself D-1 receptor manipulation did not affect water intake, but influenced QNP polydipsia that, accordingly, was enhanced by the lower dose of SKF (0.3 mg/kg) and inhibited by the lower dose of SCH (0.01 mg/kg). In rats trained to discriminate AMPH from solvent, QNP partially generalized for the AMPH stimulus, an effect that was potentiated by SKF. In conclusion, a D-1-modulated sensitization of D-2 dopaminergic mechanisms is probably involved in AMPH-induced hyperdipsi
Tolerance does not develop to the suppressant effects of (-)-norpseudoephedrine on ingestive behavior in the rat.
No full text(-)-Norpseudoephedrine (NPE), the enantiomer of cathine and a structural analog of phenylpropanolamine, shows anorectic and antidipsic effects that have been referred to its structural analogies with amphetamine. When amphetamine is chronically administered to rats, its anorectic effects fade out, water intake is progressively increased, and the diuretic response to the drug remains stable. Our previous studies show that chronic administration of NPE does not produce the typical amphetamine hyperdipsic response. In the present study, designed to obtain a more detailed picture of the ingestive and diuretic effects of chronic exposure to NPE, we evaluated the effects of 11 daily administrations of three doses of NPE (17, 32, and 56 mg/kg IP) on food and water intake, as well as on diuresis, in rats maintained in conditions of free access to food and water. Results show that all three doses inhibited food intake at 2 h, whereas only the highest dose inhibited food intake at 5 h. No differences between groups were detected at 24 h. These responses remained unchanged throughout the 11 days of treatment, and substitution of NPE with a solvent injection caused no rebound feeding. NPE treatment did not modify the ingestive response to a challenge injection of amphetamine, 0.56 and 1.0 mg/kg IP, given 1 day apart. Although NPE inhibited water intake throughout the experiment, it did so significantly only during the first 2 h postinjection. Urine output in the NPE-treated groups increased significantly on the first day only. These findings make it unlikely that the anorectic effects of NPE depend on an amphetamine-like mechanism of action. In addition, the short-lasting anorectic and antidipsic effects of NPE and the lack of tolerance to them raise the possibility of a therapeutic use of this drug as an adjuvant in the therapy of eating disorders characterized by binge episode
(-)-Norpseudoephedrine, a metabolite of cathinone with amphetamine-like stimulus properties, enhances the analgesic and rate decreasing effects of morphine, but inhibits its discriminative properties.
No full textLike psychomotor stimulants, a weak amphetamine-like agent, such as phenylpropanolamine, enhances the analgesic effects of morphine (MOR). Thus, it is possible that full psychomotor stimulant potency is not required to increase the analgesic action of opiates. The validity of this assumption is here tested by studying the ability of (-)-norpseudoephedrine (NPE), an enantiomer of phenylpropanolamine and a metabolite of cathinone, to influence both the analgesic effects of MOR and its discriminative stimulus properties. In mice NPE (5.6-10.0-17.0 mg/kg i.p.) did not prolong the latency to lick or to remove paws from a plate warmed at 54 degrees C. However, it significantly potentiated the analgesic effect of 3.2 mg/kg of MOR. These results were replicated in rats by use of the formalin test, which measures the numbers of hind paw flinches produced by injecting 50 microl of formalin into the dorsal surface of the paw. The higher dose of NPE (17 mg/kg) increased the effect of sub-analgesic doses of MOR (0.56 and 1.0 mg/kg). In rats trained to discriminate between 0.5 mg/kg of amphetamine and solvent in a two-lever operant behavior reinforced by water access. NPE induced a dose-dependent increment of drug lever responding from 0% at 1.0 mg/kg to 100% at 32.0 mg/kg. In contrast, NPE did not generalize for the MOR cue up to the dose of 56.0 mg/kg, which produced a substantial reduction of the response rate. However, when given in combination, NPE attenuated the discriminative effects of MOR and potentiated its inhibitory action on the response rate. These results exclude a direct action of NPE on the mu opiate system. In conclusion, NPE preserves amphetamine-like properties and these properties are probably responsible for the interaction of the drug with the analgesic and discriminative effects of MOR. Therefore, this study contradicts the assumption that the analgesic effects of MOR can be enhanced by a sympathomimetic drug that lacks significant psychostimulant actions
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
The assessment of drivers’ acceptance of automated vehicles in Italy: Development and initial validation of a short self-report measure
No full textAutonomous vehicles (AVs) have the potential to transform mobility. Exploring factors influencing driver’ acceptance of AVs has become crucial. We aimed at developing a short measure assessing: (a) positive dispositions towards technology (Technology Optimism Scale; TOS); (b) positive dispositions towards automated vehicles (Perception of Automated Vehicles; PAV); and (c) sustainable mobility attitudes (Sustainable Mobility Attitudes; SMA) in Italy. A sample of 730 Italian community-dwelling adult participants (mean age = 36.39 years; 61.1% female), was administered the TOS, PAV, and SMA items. Bivariate and multivariate item analyses were carried out; moreover, exploratory graph analysis was conducted to examine the structure of the measure. Internal consistency estimates of the TOS, PAV and SMA total scores were computed; associations between TOS, PAV, and SMA total scores, and demographic variables and personality traits, respectively, were assessed. The TOS, PAV, and SMA total scores were provided with adequate reliability and showed meaningful relationships with selected demographic variable and personality traits. Our findings may represent a useful contribution to the available literature on AVs providing researchers a short measure to assess different aspects contributing to the perception of AVs, at least among Italian community-dwelling participants
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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