Navegando por Palavras-chave "elevated plus-maze"

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    The anxiolytic effect of pregnancy in rats is reversed by finasteride
    (Elsevier B.V., 2006-11-01) Faturi, Claudia de Brito; Teixeira-Silva, Flavia; Leite, Jose Roberto; Universidade Federal de Sergipe (UFS); Universidade Federal de São Paulo (UNIFESP)
    Several studies have shown the influence of the oestrous cycle on anxiety levels and the important role of progesterone in this effect. the metabolism of this steroid hormone yields neuroactive steroids among them allopregnatiolone (alloP) and allotetrahydrodeoxycorticosterone (alloTHDOC), which bind to GABA(A) receptors and have anxiolytic effects. Considering that during pregnancy there is an increase in levels of both progesterone and its metabolites, the main objectives of this work were: (1) to assess changes in anxiety levels during pregnancy and (2) to verify the role of alloP and alloTHDOC in this process using finasteride, an inhibitor of 5 alpha-reductase, the enzyme responsible for their synthesis.The results showed a significant reduction in anxiety levels on the 19th day of pregnancy, which was reversed by finasteride, suggesting a role for alloP and alloTHDOC in the anxiolytic process. (c) 2006 Elsevier Inc. All rights reserved.
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    Anxiolytic-like effects of rose oil inhalation on the elevated plus-maze test in rats
    (Elsevier B.V., 2004-02-01) Almeida, R. N. de; Motta, S. C.; Faturi, C. D.; Catallani, B.; Leite, JR; Univ Fed Paraiba; Universidade Federal de São Paulo (UNIFESP)
    The effect of rose oil inhalation (1.0%, 2.5%, and 5.0% w/w) on the elevated plus-maze (EPM) test was investigated in adult male rats and compared with the effect of diazepam (DZP) (1.0 and 2.0 mg/kg) administered intraperitoneally 30 min before testing. Exposure to rose oil produced an anxiolytic-like effect similar to DZP (anxiolytic reference drug). Thus, at some concentrations, rose oil significantly increased the number of visits to and time spent in the open arms of the EPM. Anxiolytic-like properties of rose oil were observed using the EPM, being consistent with other behavioral and clinical studies. (C) 2003 Elsevier Inc. All rights reserved.
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    Behavioral differences between subgroups of rats with high and low threshold to clonic convulsions induced by DMCM, a benzodiazepine inverse agonist
    (Elsevier B.V., 2005-11-01) Contó, Marcos Brandão [UNIFESP]; Carvalho, JGB de; Venditti, Marco Antonio Campana [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In epileptic patients, there is a high incidence of psychiatric comorbidities, such as anxiety. Gamma-aminobutyric acid (GABA) ionotropic receptor GABA(A)/benzodiazepine allosteric site is involved in both epilepsy and anxiety. This involvement is based on the fact that benzodiazepine allosteric site agonists are anticonvulsant and anxiolytic drugs; on the other hand, benzodiazepine inverse agonists are potent convulsant and anxiogenic drugs. the aim of this work was to determine if subgroups of rats selected according to their susceptibility to clonic convulsions induced by a convulsant dose 50% (CD50) of DMCM, a benzodiazepine inverse agonist, would differ in behavioral tests commonly used to measure anxiety (elevated plus-maze, open field) and depression (forced swimming test). in the first experiment, subgroups of adult male Wistar rats were selected after a single dose of DMCM and in the second experiment they were selected after two injections of DMCM given after an interval of 1 week. Those rats presenting full clonic convulsions were termed Low Threshold rats to DMCM-induced clonic convulsions (LTR) and those not having clonic convulsions High Threshold rats to DMCM-induced clonic convulsions (HTR). in both experiments, only those rats presenting full clonic convulsions induced by DMCM and those not showing any signs of motor disturbances were used in the behavioral tests. the results showed that the LTR subgroup selected after two injections of a CD50 of DMCM spent a significantly lower time in the open arms of the elevated plus-maze and in the off the walls area of the open field; moreover, this group also presented a higher number of rearings in the open field. There were no significant differences between HTR and LTR subgroups in the forced swimming test. LTR and HTR subgroups selected after only one injection of DMCM did not differ in the three behavioral tests. To verify if the behavioral differences between HTR and LTR subgroups of rats selected after two injections of DMCM were due to the clonic convulsion, another experiment was carried out in which subgroups of rats susceptible and nonsusceptible to clonic convulsions induced by a CD50 of picrotoxin, a GABA(A) receptor channel blocker, were selected and submitted to the elevated plus-maze and open field tests. the results obtained did not show any significant differences between these two subgroups in the elevated plus-maze and open field tests. in another approach to determine the relation between fear/anxiety and susceptibility to clonic convulsions, subgroups of rats were selected in the elevated plus-maze as more or less fearful/anxious. the CD50 for clonic convulsions induced by DMCM was determined for each of these two subgroups. the results showed a significantly lower CD50 for the more fearful/anxious subgroup, which means a higher susceptibility to clonic convulsions induced by DMCM. the present findings show a relation between susceptibility to clonic convulsions and fear/anxiety and vice versa which may be due to differences in the assembly of GABA(A)/allosteric benzodiazepine site receptors in regions of the brain. (c) 2005 Elsevier Inc. All rights reserved.
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    Does the increase in locomotion induced by ethanol indicate its stimulant or anxiolytic properties?
    (Elsevier B.V., 2000-10-01) Boerngen-Lacerda, R.; Souza-Formigoni, MLO; Universidade Federal de São Paulo (UNIFESP); Univ Fed Parana
    The responses of mice to low doses of acutely and chronically administered ethanol (2.0 g/kg) and diazepam (2.0 mg/kg) were observed in the activity cages, the open field and the elevated plus-maze. After prolonged administration, ethanol significantly increased locomotion in the activity cages and the plus-maze. in the open field, an increase was only observed in the tests performed after 7 and 14 days of treatment. Ethanol increased the open-arm time in the plus-maze in all the tests, including after acute administration, suggesting an anxiolytic effect. Diazepam induced an anxiolytic effect after 14 days of daily injections but had no stimulant effect on locomotion. Moreover, after prolonged administration sensitization to the anxiolytic, but not to the stimulant effect, was observed. in short, the present paper's data support the hypothesis that the stimulant and anxiolytic effects of ethanol are probably being mediated by distinct mechanisms. Furthermore, these data support the hypothesis that drugs that lead to abusive use, such as ethanol, may act both as positive and negative reinforcement. (C) 2000 Elsevier Science Inc. All rights reserved.
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    One-trial tolerance to the effects of chlordiazepoxide in the elevated plus-maze is not due to acquisition of a phobic avoidance of open arms during initial exposure
    (Elsevier B.V., 2002-06-21) Frussa-Filho, R.; Ribeiro, R. D.; Universidade Federal de São Paulo (UNIFESP)
    A single exposure to the elevated plus-maze (EPM) test of anxiety reduces or abolishes the anxiolytic-like efficacy of benzodiazepines. This phenomenon called one-trial tolerance has been suggested to represent the acquisition of a phobic-like response to the open arms during trial 1. the present study was designed to examine the effects of chlordiazepoxide (5 mg/kg, ip) on the behaviour of rats in a conventional EPM apparatus after previous exposure to a four-open-arm EPM, a four-enclosed arm EPM or a conventional EPM, as well as in naive rats. Chlordiazepoxide had clear-cut anxiolytic-like effects (increased percentage of time spent on the open arms) in a traditional EPM in naive rats and in animals previously exposed to a four-open-arm EPM. However, it was ineffective in rats previously exposed to a traditional or a four-closed-arm EPM. Thus, the phenomenon of one-trial tolerance does not depend upon initial open-arm experience. (C) 2002 Elsevier Science Inc. All rights reserved.
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    The phenomenon of one-trial tolerance to the anxiolytic effect of chlordiazepoxide in the elevated plus-maze is abolished by the introduction of a motivational conflict situation
    (Elsevier B.V., 1999-07-30) Pereira, JKD; Vieira, R. J.; Konishi, C. T.; Ribeiro, R. D.; Frussa, R.; Universidade Federal de São Paulo (UNIFESP)
    A single exposure to the elevated plus-maze test of anxiety reduces or abolishes the anxiolytic efficacy of benzodiazepines. the present study was designed to examine whether this phenomenon of one-trial tolerance resulted from a motivational deficit on trial 2. We hypothesized that whereas there is a motivational conflict on trial 1 in relation to the open arms (exploration drive X natural fear of open spaces), there is mo reason for an animal to explore it on trial 2. A motivational conflict was introduced on trial 2 by rendering the enclosed arms of the apparatus aversive on trial 1. Thus, every time rats entered the enclosed arms, an aversive situation (light and hot air blow) was produced until they left the arm. On trial 2, rats did not receive this aversive stimulation. Chlordiazepoxide significantly enhaced the percent open arm time as well as the percent open arm entries on trial 2 in rats that had been submitted to the aversive stimulation in the enclosed arms on trial 1, but was not effective in rats which had been exposed to the apparatus in the absence of the aversive stimulation on trial 1. in addition, there was no difference in the percent open arm time and entries on trial 2 between saline-treated rats submitted to the aversive or non-aversive condition on trial 1. the aversive condition on trial 1 did not modify the number of total arm entries on trial 2, either. the results suggest that the anxiolytic effect of chlordiazepoxide in the elevated plus-maze depends on the presence of a motivational: conflict situation. (C) 1999 Elsevier Science Inc.
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    Possible anxiolytic effect of two extracts of Passiflora quadrangularis L. in experimental models
    (Wiley-Blackwell, 2007-05-01) Castro, Pollyanna Celso F. de; Hoshino, Alberto; Silva, Jair Campos da; Mendes, Fulvio Rieli; Universidade Federal de São Paulo (UNIFESP); CESUPA; UEPA
    Several species of the genus Passiflora, known in Brazil as 'maracuja', have widespread use in folk medicine as sedatives and anxiolytics. the anxiolytic activities of aqueous and hydroalcohol extracts of Passiflora quadrangularis leaves were evaluated using the elevated plus-maze, open held and holeboard tests. the hydroalcohol extract presented results suggestive of anxiolytic activity in dosages around 100, 250 and 500 mg/kg, as expressed by elevation of the time spent on the open arms in the plus-maze; a decrease of freezing and an increase of deambulation and rearing in the open field lest. the hydroalcohol extract showed results similar to diazepam on the holeboard. No positive results were found for the aqueous extract. Copyright (c) 2007 John Wiley & Sons, Ltd.
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    Role of learning of open arm avoidance in the phenomenon of one-trial tolerance to the anxiolytic effect of chlordiazepoxide in mice
    (Elsevier B.V., 2005-03-25) Calzavara, M. B.; Patti, C. L.; Lopez, G. B.; Abilio, V. C.; Silva, R. H.; Frussa, R.; Universidade Federal de São Paulo (UNIFESP)
    A single exposure to the elevated plus-maze (EPM) test of anxiety reduces or abolishes the anxiolytic efficacy of benzodiazepines on a second trial. Some possible explanations to the occurrence of this phenomenon (one-trial tolerance-OTT) involve behavioral modifications thought to be consequence of some kind of learning in the first trial. in the present study, the influence of learning-impairing situations on the effects of the benzodiazepine chlordiazepoxide on mice re-tested in the EPM is investigated. the results showed that: (1) as expected, the administration of chlordiazepoxide to mice re-tested in the EPM- under the same conditions of the first trial- failed to induce anxiolysis; (2) a decreased percent time in the open arms was observed on the second trial of mice exposed to both trials under the same experimental conditions; (3) neither the increase in open arm avoidance by mice re-exposed to the EPM nor the OTT to chlordiazepoxide effect were modified by administration of the amnestic agent scopolamine; (4) the decrement of the duration of the first trial to 1 min or the change in light and noise conditions in both trials counteracted the increase in open arm avoidance on trial 2; (5) none of the later procedures modified the phenomenon of OTT. Although not discarding the modulation exerted by other memory processes in the OTT phenomenon, the results indicate that situations that impair the learned avoidance response to the open arms in the EPM do not modify the phenomenon of OTT. (c) 2005 Elsevier Inc. All rights reserved.