On central effects of serotonin re-uptake inhibitors: quantitative EEG and psychometric studies with sertraline and zimelidine

Identification of 5-HT3 recognition sites in the ferret area postrema

The 5-HT3 receptor antagonist [3H]zacopride was used to identify 5-HT3 recognition sites in the ferret area postrema. Specific binding was determined by the inclusion of the 5-HT3 receptor antagonist BRL 43694 in the incubation media, and was shown to be much higher in the area postrema than in other brain regions. The increased binding in the area postrema may reflect either a greater number of binding sites, a higher affinity for such sites, or both. The results indicate that 5-HT3 recognition sites are present within the area postrema and may afford an antiemetic site of action for zacopride and other 5-HT3 receptor antagonists.

Paroxetine, a selective 5-hydroxytryptamine uptake inhibitor with antidepressant properties, lacks amphetamine-like stimulus properties in an operant drug discrimination bioassay in rodents

To evaluate whether the novel antidepressant paroxetine has any possible amphetamine-like actions, rats were trained to discriminate (+)-amphetamine sulphate in a standard two lever operant drug discrimination (DD) procedure using a fixed ratio 10 schedule of food reinforcement with a quantal, lever selection, index of the amphetamine stimulus. The 'training' dose of amphetamine was 1 mg kg-1, i.p. Rats trained with this dose of amphetamine (n = 15) learned the drug discrimination rapidly over 30 training sessions and discriminative performance in these animals was subsequently maintained at a high level of accuracy (90% correct) over a prolonged time. In tests in these trained animals, amphetamine itself and the antidepressant agents nomifensine and tranylcypromine all produced clear, unequivocal dose-related generalization to amphetamine with ED50s of 0.2, 0.5 and 1.6 mg kg-1 respectively (as determined by probit analyses). In tests with paroxetine hydrochloride it was established that, over the dose range 0.3 to 10 mg kg-1, no evidence was seen of generalization to the amphetamine stimulus. These data confirm earlier studies which suggested that some antidepressants may possess abuse potential because of their ability to induce amphetamine-like internal states. In contrast, paroxetine is devoid of such properties.