ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;The responding of eight pigeons was maintained under a fixed‐ratio 30 schedule of food reinforcement. While the pigeons were maintained at 80% of their free‐feeding body weights the effects of presession injection of a range of cocaine doses (1.0 or 3.0 mg/kg to 10.0 or 17.0 mg/kg) were determined. The weights of one group of pigeons were then increased to between 90 and 100% of their free‐feeding weights, while the other group's weights were reduced to 70% of their free‐feeding weights. The effects of cocaine were determined again. Following this, pigeons' weights were adjusted to the percentage of free‐feeding weight to which they had not yet been exposed, and the effects of cocaine determined a third time. Cocaine produced dose‐dependent decreases in response rates. Decreases were observed at smaller cocaine doses when pigeons were relatively food‐satiated (i.e. 90‐100% of free‐feeding weight); larger doses were required to decrease responding when pigeons were main‐tained at 70% free‐feeding weight. If increased resistance to the behaviorally suppressive effects of cocaine when food deprivation levels are increased occurs also when cocaine is self‐administered, this could help account for increases in amounts of cocaine‐reinforced behavior under conditions of food deprivation.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;The effects of sertindole, clozapine,Cis(Z)‐flupentixol and haloperidol on the discriminative stimulus properties ofd‐amphetamine (dopamine DA stimulant),d‐LSD (5‐HT2agonist) and St 587 (&agr;1‐adrenoceptor agonist; 2‐chloro‐5‐trifluoromethyl‐phenylimino)‐imidazolidine) have been studied. Sertindole, a putative antipsychotic compound with limbic selectivity, antagonized the effects ofd‐LSD and St 587, whereas that ofd‐amphetamine was unchanged. Clozapine preferentially inhibited St 587, but also antagonizedd‐LSD andd‐amphetamine, together with increases in reaction time.Cis(Z)‐flupentixol antagonizedd‐amphetamine and St 587 effects, whereas haloperidol antagonizedd‐amphetamine only. Behavioural disruption was induced by haloperidol in St 587 andd‐LSD‐trained animals. The 5‐HT2antagonist ketanserin selectively inhibited the effect ofd‐LSD, and the selective &agr;1‐adrenoceptor antagonist prazosin partially inhibited the effect of St 587, but did not inhibitd‐LSD ord‐amphetamine. The partial inhibition of St 587 effects by prazosin was not further increased by co‐treatment with haloperidol. Prazosin partially substituted for the training dose of St 587. The results indicate that drug discrimination techniques can be used to demonstrate different activity profiles of typical and atypical neuroleptics. The classical neuroleptics have preferential amphetamine antagonistic activity, whereas clozapine has a broad activity profile. Furthermore, the atypical neuroleptic sertindole fails to induce acute DA antagonism in doses much higher than those inhibitingd‐LSD and St 587.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;The effects of nitrous oxide at subanesthetic doses (0%, 10%, 20%, and 40% in oxygen) on mood and psychomotor performance were determined in a group of 12 healthy volunteers (six males and six females). A randomized, placebo‐controlled, double‐blinded, crossover trial of five experimental sessions was used. Effects were measured before, during and after a 30‐min inhalation period of the agent, using three subjective effects questionnaires (the Profile of Mood States, the Addiction Research Center Inventory, and the Visual Analogue Scale); and two psychomotor tests (auditory reaction time and Digit Symbol Substitution Test). In addition, an End‐of‐Session questionnaire, administered 60 min after cessation of inhaling the agent, was used, which measured the subjects' reactions to the agent inhaled that day (i.e. peak concentration effect and concentration liking). The primary effects observed from nitrous oxide were confined to the inhalation of 20% and 40% concentrations. Subjects became more confused, sedated, high, dysphoric, and stimulated during inhalation of 40% nitrous oxide; fatigue, depression and anxiety increased after inhalation of 40% nitrous oxide had ceased. Significant or near‐significant differences on several measures of subjective effects emerged between sexes. On the End‐of‐Session questionnaire, subjects' ratings of the peak effect of nitrous oxide were dose‐related. There was individual variation in the degree to which subjects liked nitrous oxide: eight of the 12 subjects reported liking the 40% concentration, one was neutral, and three did not like it. Subjects' performance on the DSST was significantly impaired during inhalation of 40% nitrous oxide, but recovered soon after inhalation stopped. In summary, nitrous oxide had robust effects on mood, there appeared to be sex differences in the magnitude of subjective effects of nitrous oxide, and there was some variability in the extent to which subjects liked the anesthetic agent.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;The effects of acute administration of the opioid compounds buprenorphine, morphine, and naloxone were studied on auditory and visual threshold functions and reaction time performances in baboons. Baboons were trained in a reaction time procedure to hold a lever depressed, and release the lever when a signal was presented. Auditory and visual signals were employed in separate sessions. Drug was administered 30 min prior to testing. Dose‐related increases in visual and auditory thresholds were observed following buprenorphine, with visual thresholds being somewhat more drug‐sensitive. Buprenorphine also increased reaction times to both high‐intensity and low‐intensity stimuli. High doses of morphine increased reaction times to high‐intensity auditory and low‐intensity visual stimuli; thresholds for both modalities were unaffected by any dose of morphine. Naloxone produced no consistent effects on thresholds or reaction times. False alarm rates were not significantly changed by buprenorphine, morphine, or naloxone.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;A runway was used to measure locomotor responses to quinpirole (200 μg/kg), in rats. The locomotor stimulant effect of quinpirole increased progressively over successive trials at 3‐day intervals. Animals administered quinpirole in the home cage were also sensitized, but to a lesser degree than animals tested in the runway following quinpirole injections. Exposure to an open field, following quinpirole injections, sensitized responsiveness in the runway to an extent comparable to that seen following runway exposure. Animals exposed to a movable running wheel, following quinpirole injections, were more sensitized to the effect of quinpirole in the runway than animals exposed to a locked running wheel. The results suggest that the extent of sensitization to quinpirole is determined by the behaviour elicited by the drug, rather than the environment in which it is administered. An operant conditioning model is proposed to account for these effects.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;Effects of the 5‐HT3 antagonist ICS 205‐930 on chlordiazepoxide (CDP) withdrawal were assessed in rats treated for 21 days with doses of CDP up to 40 mg/kg/day (b.i.d.). Withdrawal signs recorded were body weight and 24h food intake, which both fell during withdrawal and then recovered. ICS 205‐930 (0.001‐1.0 mg/kg) was administered b.i.d. during withdrawal. At no dose over the wide range tested did ICS 205‐930 reduce withdrawal signs. These data contrast with published findings with the 5‐HT3 antagonist ondanestron, some of which indicated that ondansetron completely alleviated the “anxiogenic” suppression of exploratory behaviour observed during benzodiazepine (BZ) withdrawal. Possible reasons for these differing findings are discussed. Collectively, these findings suggest that 5‐HT3 antagonists may have limited utility in the clinical treatment of BZ withdrawal.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;Using a reaction time task sensitive to neuroleptic disruption, we have examined the ability of the non‐competitive NMDA antagonist MK‐801 (0.01‐0.16 mg/kg) to reverse impairments induced by chlorpromazine (2.0 mg/kg). Rats were required to depress a lever for a randomly determined duration, and release it within 1 sec of a light cue in order to obtain food reward. Chlorpromazine reduced the overall number of lever presses, caused an early cessation of responding, slowed lever release in response to an external cue, and increased the time taken to reach the food hopper after a correct response. MK‐801 differentially influenced these impairments, with no dose of drug completely normalising behaviour. The reduction in response levels and early termination of responding were partially reversed by MK‐801, whilst certain doses of the drug completely reversed the increased time taken to reach the food hopper. Although MK‐801 increased the likelihood that chlorpromazine‐treated rats would release the lever within the 1 sec criterion time to obtain reinforcement, reaction times with the drug combination were still slower than observed in the control session. Therefore, MK‐801 appears to be less effective in reversing the chlorpromazine‐induced deficit in movement initiation than certain other aspects of performance in this task. These findings are less promising than those from other studies which have been used to suggest a clinical use of NMDA antagonists in the treatment of idiopathic and neuroleptic‐induced parkinsonism.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

&NA;Rhesus monkeys (n= 5), surgically implanted with double‐lumen catheters, were allowed to self‐administer cocaine (0.1 or 0.3 mg/kg/injection, i.v.) on one lever (COC lever) under several fixed‐interval schedules of reinforcement. Responding on a second lever (SAL lever) delivered saline (i.v.) under a fixed‐ratio 1 schedule. Responding on both levers was a bitonic function of interval value and cocaine dose. A variety of experimental conditions were examined to determine whether SAL lever responding could be considered to be adjunctive in nature. SAL lever responding did not change when saline injections were discontinued, suggesting that SAL lever responding was not maintained by interoceptive stimuli associated with the injection. Discontinuation of various exteroceptive stimulus changes that had occurred as a consequence of SAL lever responding also did not affect the frequency of SAL lever responding. However, when there was no stimulus change following a SAL lever response, response rates on that lever decreased by approximately 40‐60% indicating that stimulus change played some role in the maintenance of the behavior. The introduction of change‐over‐delays (2‐16 s) between responding on the SAL and COC levers had little or no effect on responding on the SAL lever, suggesting that SAL lever responding was not maintained by adventitious reinforcement by cocaine injections. SAL lever responding also occurred in these same monkeys when cocaine was available under fixed‐time or variable‐interval schedules of reinforcement. These results confirm that presentation of cocaine under interval schedules of reinforcement can generate substantial amounts of behavior (pressing the SAL lever) that is not necessary for obtaining the drug. Further, the results strongly suggest that the behavior can be classified as an adjunctive behavior that is similar to adjunctive behaviors generated by the intermittent presentation of other positive reinforcers.

ISSN:0955-8810    

出版商:OVID    

年代:1992

数据来源: OVID