Nicotine produces behavioural signs which are, in part, characteristic of dopaminergic activation. In the present study, it was investigated, to which degree these signs can be conditioned. The drug produced dose-dependent (0.15-0.60 mg/kg s.c.) increases in locomotor activity, hyperkinesia and stereotyped sniffing. The effects produced by 0.6 mg/kg nicotine were significantly inhibited by mecamylamine (1 mg/kg i.p.), but only in part by haloperidol (0.2 mg/kg i.p.). In a subsequent series, the administration of nicotine (0.6 mg/kg s.c.) was repeatedly associated with well-defined environmental (conditioned) stimuli: a wire cage associated with an auditory and an olfactory stimulus. Another group was pseudoconditioned, a third group remained drug-naive. When the animals were given saline in presence of the conditioned stimuli 24 h after the last conditioning session, locomotor activity, hyperkinesia and stereotyped sniffing were significantly higher in conditioned than in pseudoconditioned and drug-native rats. Similarly, when the rats were injected with nicotine (0.6 mg/kg s.c.) in presence of the conditioned stimuli 24 h after the last conditioning session, locomotor activity and stereotyped sniffing were most pronounced in the conditioned animals. These results demonstrated that behavioural effects of nicotine can be conditioned. Phenomena of this kind might contribute to the addictive behaviour to nicotine.

Animals↗

PubMedDate not supplied

Comparison of the action of the 5-HT2 antagonists amperozide and trazodone on preference for alcohol in rats.

Previous studies in the rat demonstrated that the 5-hydroxytryptamine2 (5-HT2) antagonist amperozide attenuates the volitional intake of both alcohol and cocaine solutions in a free-choice situation. However, another 5-HT2 antagonist, ritanserin, has not been found to reduce alcohol drinking consistently in the rat. In this study, trazodone was compared to amperozide for its effect on the volitional consumption of alcohol because, like amperozide, trazodone is a potent 5-HT2 receptor antagonist but a weak inhibitor of 5-HT reuptake. Male Sprague-Dawley rats were induced to drink alcohol by 10 mg/kg cyanamide injected for 3 days b.i.d. One week later the rats were offered a choice of water and increasing concentrations of alcohol solutions ranging from 3% to 30% v/v in a three-bottle two-choice paradigm. After the concentration of alcohol that produced maximal daily intake was determined for each rat, trazodone or amperozide was injected b.i.d. SC in doses of 1.0 mg/kg or 2.5 mg/kg for three days. Whereas the higher dose of amperozide produced a significant, 55.6% decrease from pretreatment baseline of alcohol intake, trazodone did not alter alcohol preference at either the 1.0- or 2.5-mg/kg dose. These results are discussed in terms of whether the antagonism of 5-HT2 receptors by amperozide is critical to its attenuating effect on preference for alcohol solutions.

Alcohol Drinking↗

PubMedDate not supplied

[Particular aspect of frontal evoked visual responses in Papie papie].

Explore the source record for details and available documents.

Animals↗