ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The present experiments compared patterns of locomotor activity during repeated acclimation sessions and determinations of locomotion and stereotypy elicited by administration of the direct dopamine receptor agonist apomorphine in five inbred strains of rats: the results suggest that each strain can be differentiated phenotypically according to these behavioral responses. Brown Norway rats demonstrated the greatest locomotion during acclimation sessions. Low doses of apomorphine (0.1 and 0.32 mg/kg) produced a flat body posture in Lewis animals. A higher dose of apomorphine (l.0mg/kg) markedly increased locomotion in Fisher rats. Buffalo animals showed licking during control sessions and the greatest increase in gnawing at higher doses of apomorphine. DA rats were less responsive than the other strains of apomorphine. Between-strains autoradiographic determination of dopamine receptor densities revealed several differences in D1 receptors labeled by3H-SCH 23390 and D2/D3 receptors labeled by125I-NCQ 298 in the caudate-putamen and nucleus accumbens. However, the heterogeneity of dopamine receptor densities was not sufficient to explain the strain-specific behavioral responses. These experiments demonstrate variations in behavioral and neurochemical characteristics of inbred strains of rats which could be used to model genetically determined differences in dopamine-mediated behavioral responses.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The high levels of drinking induced by intermittent food-reinforcement schedules are dose-dependently reduced by acute doses of d-amphetamine. The present study evaluated whether the effects of d-amphetamine on this schedule-induced drinking reflect the reduction of high rates of responding. Twenty four rats were divided into six groups (n = 4) according to the interval and time durations of a multiple fixed-time (FT) fixed-interval (FI) schedule (15 s, 30 s, 60 s, 120 s, 240 s and 480 s). FT components were signalled by a tone and by lever withdrawal. Doses of 0.25 to 4.0 mg/kg of d-amphetamine were administered i.p. 10 min before test sessions, d-amphetamine produced similar dose-dependent reductions in rate of licking induced by FT and FI schedules. Rate-decreasing effects on operant lever pressing were also found after administrations of d-amphetamine. The dose-dependent decrements produced by d-amphetamine were a function of the infer-food interval length in both schedule-induced and operant behaviours. These rate-decreasing effects were rate-dependent, but d-amphetamine interacted differentially with control rates of adjunctive and operant behaviours, causing a greater suppression of the lower rates of adjunctive licking and the higher rates of operant lever pressing.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Marble burying has been suggested as a model of obsessive-compulsive disorder (OCD) based on the fact that specific serotonin reuptake inhibitor selectively influenced this response. Studying the behaviour we observed that mice also exhibited intense digging activity in the absence of glass marbles. This digging activity showed no habituation either between sessions or within a session and it could be inhibited by psychotropic drugs in a manner similar to the marble burying response. On the basis of the results a methodological and a theoretical conclusion can be drawn. First, it is concluded that glass marbles themselves do not necessarily provide a fear-provoking stimulus but they serve rather as a convenient means of measuring the intensity of digging activity. Alternative ways of measuring the intensity of digging gave high correlations with marble burying. Second, the behaviour observed is not burying (the marbles) but digging) burrowing (the bedding material), Which is elicited by the presence of a “diggable” ground. The putative compulsive nature of this behaviour may add support to the hypothesis that marble burying may be a model of OCD.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Reexposure to alcohol may induce subjective carving and relapse to drug self-administration in ex-alcoholics. In this study, we proposed a rat model of “first-drink” -induced drug-seeking relapse. Responding was established in Long Evans rats under a fixed-ratio [FR5:Sr] schedule for oral ethanol. Substitution of water for ethanol solution resulted in extinction of the self-administration. When responding for 8% ethanol and ethanol intake were stable for at least three consecutive 30 min sessions, ethanol delivery was discontinued and only three water dipper cup presentations were available upon responding (3[FR5:water]). When the number of active lever presses decreased to a low stable level, responding was considered extinguished. In Experiment 1, subjects under “extinction” were challenged with three 8% ethanol dipper cup presentations. The re-exposure to ethanol was able to significantly reinstate responding in all subjects. Latency to complete the ethanol presentation significantly decreased compared In the value observed during the previous “extinction” session. In Experiment 2. other subjects were tested for extinction and then reexposed to 4. 8 or 16% ethanol. All three concentrations significantly increased active lever presses, but with different patterns of responding. The resumption of responding was linearly correlated to the ethanol concentration but no significant dose-effect relationship was found. In Experiment 3, reexposure to 8% ethanol in nondeprived rats induced a resumption of responding not significantly different from the effect observed in a restricted diet condition. These results demonstrate that ethanol reexposure is able to reinstate ethanol-seeking behaviour in rats with a past history of ethanol self-administration, and that this effect does not depend on a food motivation drive related to the calorific value of ethanol.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

In previous studies, it was shown that apomorphine-induced stereotyped behaviour could be conditioned when apomorphine was repeatedly paired with sensory stimuli (CS). Since in these experiments, the sum of various sensory stimuli were applied, it seemed of interest to use each sensory stimulus separately in order to evaluate the relevance of each of the stimuli for the development of the conditioned responses (CRs). Therefore, apomorphine (0.5 mg/kg s.c.) was repeatedly (six times) paired either with an auditory, an olfactory, a tactile or a compound (auditory + olfactory + tactile) stimulus. On the seventh (drug-free test) day, the rats were injected with solvent in the presence of the CS previously applied. It was shown that the olfactory stimulus alone when used as CS produced similar CRs (in particular, stereotyped sniffing and licking) as the compound stimulus, whereas the other stimuli applied did not noticeably contribute to the development of the CRs. Furthermore, similarly to the compound stimulus, the olfactory stimulus, but not the auditory or tactile one, enhanced the apomorphine-induced stereotypies in the presence of the CS. This result suggests that the application of olfactory stimuli might be of particular relevance for the development of conditioned dopaminergic responses.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Latent inhibition (LI) is a measure of retarded conditioning to a previously-presented nonreinforced stimulus, that is impaired in schizophrenic patients and in rats treated with amphetamine. Neuroleptic drugs are known to produce two effects in this test paradigm: to antagonise amphetamine-induced disruption of LI, and to enhance LI when administered on their own. The present experiments tested the effects on LI of a potential antipsychotic, sigma ligand BMV-14802. The experiments used a conditioned emotional response (CER) procedure in rats licking for water, consisting of three stages: preexposure, in which the to-be-conditioned stimulus (a tone) was repeatedly presented without being followed by reinforcement; conditioning, in which the preexposed stimulus was paired with reinforcement (a foot shock); and test, in which LI was indexed by animals' degree of suppression of licking during tone presentation. In Experiment 1, 20 tone preexposures and two conditioning trials were given and the effects of 5, 15, and 30 mg/kg BMY-14802 were assessed. Experiment 2 tested the effects of 15 and 30 mg/ kg on LI using ten preexposures and two conditioning trials. Experiment 3 investigated the effects of 15 and 30 mg/kg on LI using 40 preexposures and extended conditioning consisting of five tone-shock pairings. Experiments 4 and 5 investigated antagonism of amphetamine-induced disruption of LI by 15 and 30 mg/kg BMV-14802, respectively. BMV-14802 was found to antagonise amphetamine-induced disruption of LI and enhance LI when low numbers of preexposures and two conditioning trials were given, but not following extended conditioning. Those results provide partial support for the suggestion that BMY-14802 may possess antipsychotic properties.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

d-amphetamine and phencyclidine (PCP) can induce a model psychosis in humans that resembles schizophrenia. Both drugs reproduce the positive symptoms of schizophrenia, but apparently only PCP mimics the negative symptoms. The purpose of this study was to determine the pharmacological profiles of d-amphetamine and PCP in the social interaction test, and to determine if they have disruptive effects on social behaviour in rats that may be comparable to the social isolation characteristic of negative symptoms. Acute and subchronic (daily for 5 days) administration of d-amphetamine (0.7 22 μmol/kg) produced stereotyped behaviour at dosages of 10.4 μmol/kg and upwards without any consistent effects on social behaviour, In contrast, acute and subchronic PCP (0.9–29 μmol/kg) produced dose dependent increases in stereotyped behaviour and ataxia as well as dose-dependent reductions in the social behaviour at dosages of 3.6 μmol/kg and upwards. Thus, d-amphetamine and PCP had distinct effects on the social behaviour of rats. Both drugs produced stereotyped behaviour and locomotor hyperactivity, but only PCP dose-dependently disrupted social behaviour. This raises the possibility that PCP-induced social isolation in rats corresponds to the social isolation reported in humans under the influence of PCP. and that it can be used as an animal model of negative symptoms.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

A large body of evidence indicates that brain monoamines are involved in the pathogenesis of mental depression, as well as in the mechanism of action of most antidepressant treatments. The present report shows that long-term exposure to imipramine (EMI) or fluoxetine (FLX) was equally potent in preventing the escape deficits produced in rats by repeated unavoidable shocks. The acute administration of SCH 23390, a selective D1 dopamine receptor blocker, shortly before the inescapable shock session entirely prevented IMI effect on escape performance, but only partially prevented that of FLX. Moreover, pindolol (an antagonist of β-adrenoceptors and of serotonin 5-HT1Aand 5-HT1Breceptors) completely antagonized the efficacy of FLX in preventing escape deficits, whereas it did not affect the activity of IMI. The acute administration of propranolol failed to alter the effect of either antidepressant. It was concluded that in rats, the efficacy of IMI in counteracting the stress-induced behavioral sequelae is mainly mediated by the activation of D1 dopamine receptors, whereas that of FLX is largely dependent upon the stimulation of post-synaptic 5-HT1Areceptors. Finally, the effects of the two drugs appear to be totally unrelated to activation of β-adrenoceptors.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The central nucleus of the amygdala is a CRF-containing limbic brain site which mediates both fear-like and avoidance behaviors, and intra-amygdala administration of a CRF antagonist blocks the increase in anxiogenic-like behavior characteristic of ethanol withdrawal. In order to evaluate the role of brain CRF in negative motivational states associated with other classes of abused dings, the present studies examined the effects of suppression of amygdala CRF systems on the characteristic aversive state of precipitated withdrawal in morphine-dependent subjects. In a place conditioning paradigm, administration of a CRF antagonist, α-helical CRF (9–41) (250 ng], bilaterally into the central nucleus of amygdala, reversed the withdrawal-induced conditioned place aversion produced by injection of the opiate antagonist, mothylnaloxonium [500 ug], into the same site. In a conditioned operant suppression paradigm, impairment of CRF neurons by immu-no-targeted toxins administered into the central nucleus of amygdala, one month prior to testing, attenuated the decrease in response rate produced by exposure to distinctive sensory cues associated previously with systemic administration of naloxone [25 μg/kg s.c.] in morphine-dependent subjects. These results indicate that suppression of intra-amygdala CRF systems weakens the aversive stimulus properties of conditioned opiate withdrawal, and suggest a general role for CRF in coordinating behavioral responses to negative motivational effects of drug withdrawal.

ISSN:0955-8810    

出版商:OVID    

年代:1995

数据来源: OVID