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The subtype of dopamine (DA) receptors mediating the yawning response to DA agonists was determined in rats. Yawning was elicited both by the mixed D1-D2 agonist apomorphine and by the specific D2 agonist LY 171555, but not by the selective D1 agonist SKF 38393. Both apomorphine- and LY 171555-induced yawning were antagonized not only by the selective D2(More)
In unanesthetized rats the intravenous administration of low doses of ethanol (0.125-0.5 g/kg) produced a dose-dependent increase (30-80%) in the firing rate of dopaminergic (DA) neurons in the Ventral Tegmental Area (VTA). In agreement with previous observations, a dose range between 0.5 and 2 g/mg of ethanol was needed to produce comparable stimulant(More)
Evidence recently provided has suggested a specific involvement of the GABAergic system in modulating positive reinforcing properties of several drugs of abuse through an action on mesolimbic dopaminergic neurons. The GABA(B) receptor agonist baclofen has been proposed as a potential therapeutic agent for the clinical treatment of several forms of drug(More)
The present paper reviews evidence on the effect of antidepressant treatments on dopamine transmission. Chronic treatment with antidepressant drugs potentiates the behavioural stimulant responses elicited by the stimulation of dopamine receptors, including reward-related behaviours. Moreover, antidepressants affect dopamine release in several brain areas.(More)
A small dose of apomorphine (25 or 50 micrograms/kg, SC) induced repeated episodes of yawning, penile erection, genital grooming and a decrease in locomotor activity in rats. Hypophysectomy almost completely abolished yawning, penile erection and genital abolished yawning, penile erection and genital grooming but failed to modify the hypomotility induced by(More)
Yawning was induced in rats by the (+) enantiomer of 3PPP, while (-)-3PPP was inactive. Yawning was present 24, but not 1, 6 and 12 h after reserpine treatment. The (+)-3PPP-induced yawning was antagonized by haloperidol and sulpiride but not by domperidone. Reserpine-induced yawning was antagonized by sulpiride and by alpha-methyltyrosine suggesting that(More)
In the present study we demonstrate that consumption of a tryptophan-deficient diet for a period of 14 days decreased the striatal serotonin and 5-hydroxyindolacetic acid tissue content in rats, whereas the level of dopamine remained unchanged. Under this condition of diminished serotonergic tone, a challenge dose of cocaine (10mg/kg, i.p.) significantly(More)
Apomorphine (50 micrograms/kg) induced repeated episodes of yawning, penile erection and genital grooming in rats. A dose of cycloheximide, which inhibited brain protein synthesis by 50% totally prevented apomorphine-induced yawning and reduced by approximately 50% the occurrence of episodes of penile erection and genital grooming. However, this treatment(More)
Numerous studies have demonstrated that genetic factors significantly influence opioid ability to induce behavioral modification in mice. This differential sensitivity has been extensively studied, particularly in the DBA/2J and C57BL/6J strains. In the present study, using the "in vivo" microdialysis technique in these strains, we investigated the effect(More)
The effect of chronic treatment with antidepressants (ADs) on the behavioral responses to LY 171555, a selective D2 receptor agonist, SKF 38393, a selective D1 receptor agonist, and B-HT 920, a selective DA autoreceptor agonist, was studied in rats. In normal rats small, intermediate and high doses of LY 171555 produced hypomotility, hyperactivity and(More)