1,720,966 research outputs found
Self-administration of the anti-inflammatory drug benzydamine in the rat: electrophysiological evidence of central glutamatergic mechanisms of action.
No full textBenzydamine (BZY) is a non steroideal anti-inflammatory drug (NSAID) used for the topical treatment of
inflammations of the oral (Tantum Verde®) and vaginal (Tantum Rosa®) mucosa. Virtually nothing is known
about the central pharmacological actions of BZY. Yet, there are reports of voluntary systemic overdosage
of BZY in drug addicts, resulting in a euphoric, hallucinatory state. In the present study, we investigated the
reward proprieties of BZY in a rat self-administration paradigm. We found that BZY has a powerful
reinforcing effect and that this effect is greatly facilitated in animals that had previously self-administered
heroin and cocaine, indicating cross sensitization between BZY and other drugs of abuse. We then assessed
the effect of BZY on cortico-accumbens glutamatergic transmission, using field recordings in rat parasagittal
brain slices. BZY dose-dependently reduced fEPSP amplitude and paired pulse ratio, suggesting a
presynaptic mechanism of action. Furthermor
Context dependent effects of heroin self administration on nucleus accumbens synaptic plasticity
No full textWe have previously reported the setting of drug self-administration has a powerful influence on drug intake(Caprioli et al. 2008). Rats that lived in the self-administration (SA) chamber (ResidentRats) tended to self-administer more heroin than rats that were exposed to the
SA chamber only during testing (NonResidentRats living in a distinct home cage). Also the neurobiological effects of heroin are a function of setting. In situ hybridization and immunohistochemistry experiments have shown that the effects of heroin on the expression of FosmRNA and Fos in the reward regions of the brain are very different in Resident vs. NonResidentRats (Paolone et al. 2007; Celentano et al. 2009). Fos is a transcription factor that is thought to be implicated in the early stages of drug-induced neuroplasticity. Thus, we hypothesized that the setting may influence heroin-induced long term plasticity.In the present study, we used ex vivo electrophysiological recordings to investigate the effects of heroin SA on long term cortico-accumbens synaptic plasticity as a function of setting. Both Resident and NonResident rats were trained to self-administer heroin (25μg/kg/infusion) for 10sessions (3h each).After 14 days of abstinence from heroin the rats were killed and their brains excised to obtain parasagittal slices for field recordings. We found that after tetanic stimulation, LTP was greater in NonResidentRats (fEPSP amplitude about 160% of baseline) than in ResidentRats
(140% of baseline). This suggests that cortico-accumbens (presumably inhibitory) inputs are reduced when the rats self-administer heroin in their home environment relative to a non-home setting and may explain why ResidentRats tend self-administer more heroin than NonResidentRat
Distinct populations of neurons activated by heroin and cocaine in the striatum as assessed by catFISH
Full text linkDespite the still prevailing notion of a shared substrate of action for all addictive drugs, there is evidence suggesting that opioid and psychostimulant drugs differ substantially in terms of their neurobiological and behavioral effects. These differences may reflect separate neural circuits engaged by the two drugs. Here we used the catFISH (cellular compartment analysis of temporal activity by fluorescence in situ hybridization) technique to investigate the degree of overlap between neurons engaged by heroin versus cocaine in adult male Sprague Dawley rats. The catFISH technique is a within-subject procedure that takes advantage of the different transcriptional time course of the immediate-early genes homer 1a and arc to determine to what extent two stimuli separated by an interval of 25 min engage the same neuronal population. We found that throughout the striatal complex the neuronal populations activated by noncontingent intravenous injections of cocaine (800 μg/kg) and heroin (100 and 200 μg/kg), administered at an interval of 25 min from each other, overlapped to a much lesser extent than in the case of two injections of cocaine (800 μg/kg), also 25 min apart. The greatest reduction in overlap between populations activated by cocaine and heroin was in the dorsomedial and dorsolateral striatum (∼30% and ∼22%, respectively, of the overlap observed for the sequence cocaine-cocaine). Our results point toward a significant separation between neuronal populations activated by heroin and cocaine in the striatal complex. We propose that our findings are a proof of concept that these two drugs are encoded differently in a brain area believed to be a common neurobiological substrate to drug abuse
Substance-specific influences of setting on drug reward: an ultrasonic vocalization study in rats self-administering heroin and cocaine.
No full textClinical and preclinical evidence indicate that the setting of drug use affects drug reward in a substance-specific manner (Caprioli et al. 2009; Badiani and Spagnolo 2013). When heroin and cocaine co-abusers, for example, report on the circumstances of drug use, they indicate distinct settings for the two drugs: heroin being used preferentially at home and cocaine preferentially outside the home (Caprioli et al. 2009; Badiani and Spagnolo 2013). Similar results were obtained in rats given the choice between these two drugs (Caprioli et al. 2007, 2008, 2009). Rats that live in the self-administration (SA) chambers (Resident rats) tend in fact to prefer heroin to cocaine, whereas rats that are transferred to the SA chambers only for the test sessions (Non-Resident rats) tend to prefer cocaine to heroin. The goal of this study was to investigate whether the affective value of cocaine and heroin changes as a function of the setting. It has been shown that rats emit ultrasonic vocalizations (USVs) in the range of 50-kHz when exposed to rewarding stimuli, whereas they emit 22-kHz USVs in the presence of aversive stimuli, suggesting that 50-kHz USVs reflect positive affective states (Burgdorf et al. 2000, 2001, 2008). In the present study, we recorded USVs in rats undergoing cocaine and heroin SA on alternate days. We found that Non-Resident rats emit more 50-kHz USVs when self-administering cocaine than when self-administering heroin. In contrast, Resident rats emit more 50-kHz USVs when self-administering heroin than when self-administering cocaine. These findings indicate that the setting of drug taking exert a substance-specific influence on the ability of drugs to induce a positive affective state
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Full text linkWe 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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