摘要:

The effects of the “atypical” antipsychotic olanzapine and several other antipsychotics were examined using a conflict schedule. Rats were trained to respond for food on a three-component schedule, comprising variable-interval 30 s (food, VI30) and fixed-ratio 10 s (food + shock, FR10) components separated by time-out (TO). Olanzapine (0.3125–1.25 mg/kg), clozapine (1.25–5 mg/kg) and chlordiazepoxide (2.5–5 mg/kg) decreased or had no effect on VI30 responding, whereas responding in the FR10 component increased. Chlordiazepoxide (5 mg/kg) also increased TO responding. The antipsychotic agents haloperidol (0.125 and 0.25 mg/kg), trifluoperazine (0.0625–0.25 mg/kg), remoxipride (1.25–5 mg/kg) and risperidone (0.0625–0.5 mg/kg) decreased VI30 responding and either had no effect, or decreased TO and FR10 rates. The anticholinergic agent scopolamine (0.03125–0.25 mg/kg) decreased VI30 responding. The 5-HT2antagonist ritanserin (2.5 and 5 mg/kg) and the anticholinergic agent trihexyphenidyl (2.5 and 5 mg/kg) had no effect on responding. Flumezanil (10 mg/kg) reduced the anticonflict effect of chlordiazepoxide but not olanzapine. These results further emphasize the unusual profile of olanzapine.

ISSN:0955-8810    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Several lines of evidence suggest that the enzyme catalase plays an important role in many of the behavioral and reinforcing effects of ethanol, through its putative role in the central production of acetaldehyde. The role of catalase in the acquisition of voluntary ethanol consumption was examined in the present experiments by administering the catalase inhibitor 3-amino-1,2,4-triazole (aminotriazole) during the presentation of an ascending series of concentrations of either ethanol or saccharin-quinine solutions. Aminotriazole (0.5 g/kg) significantly attenuated consumption of both ethanol and saccharin-quinine solutions throughout the acquisition period, and this effect remained during a subsequent maintenance period during which no injections were administered. Drinking did recover, however, when the acquisition procedure was reinstated. These results suggest that the effect of aminotriazole on the consumption of ethanol and saccharin-quinine may be the result of a change in reactivity to taste, or an aversive effect caused by drug administration.

ISSN:0955-8810    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

A-68930 [1R,3S)-1-aminomethyl-5,6-dihydroxy-3-phenylisochroman HCI] is a novel, potent and selective dopamine D1 receptor agonist. Previous reports have shown that the selective D1 partial agonist, SK&F 38393, reduced food consumption in rats and mice. The aim of this study was to undertake a microstructural analysis of the effects of A-68930 on food intake and feeding behaviour in non-deprived male rats trained to consume a highly palatable diet in a 20 min period. A-68930 (0.1–1.0 mg/kg, s.c.) produced a dose-dependent reduction in food intake, which was due to a reduction in the frequency of bouts of feeding but not to a reduction in bout duration. A-68930 had little effect on the latency to initiate feeding or on the local rate of eating. Hence, it had a selective action on the parameters of eating, which is distinctly different from the effects of selective D2 agonists or of indirectly acting psychomotor stimulants like cocaine. A-68930 also increased grooming by lengthening the grooming bouts, and reduced locomotion and rearing responses. At the largest dose, immobility was increased. The anorectic effect of A-68930 may reflect, at least in part, the increased grooming it produces.

ISSN:0955-8810    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The lack of procedures which can unequivocally demonstrate cannabinoid self-administration in animals has been an obstacle to the study of the neural basis for the reinforcing effects of this drug class. Because Δ9-tetrahydroeannabinol (Δ9-THC) produces a relatively slow-onset, long-lasting behavioral effect, a self-administration procedure with widely spaced drug deliveries was evaluated as an alternative to fixed-ratio schedules which typically require frequent, closely spaced injections to demonstrate reinforcing effects. Three adult male rhesus monkeys were surgically implanted with intravenous catheters and trained to self-administer phencyclidine (PCF) under a 10 min fixed-interval schedule of reinforcement. Three injections were available each day, separated by 2 h periods during which responding had no programmed consequences. In an attempt to link the effect of the drug with the response which produced it, each 20 s injection was paired with a red light which remained illuminated for 10 min. PCP (100 μg/kg/injection) maintained steady rates of responding during each availability period, ranging from approximately 0.2 to 0.7 responses/s. During 7 day substitution periods, Δ9-THC (17–100 μg/kg/injection) maintained low rates of responding which occasionally surpassed those during vehicle substitutions, but fell far below rates maintained by PCP. Substitution tests with the potent Δ9-THC analog CP 55,940 also resulted in low rates of responding. These results demonstrate that Δ9-THC is a poor reinforcer in animals, even under conditions where some of its unfavourable biodispositional properties are taken into consideration.

ISSN:0955-8810    

出版商:OVID    

年代:1994

数据来源: OVID