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Non conditioned sensitization to the motor stimulant effects of caffeine depends on previous exposure to dopamine D1 but not D2 receptor agonists
No full textRole of dopamine receptors in the induction and expression of rotational behavior induced by caffeine in 6-hydroxydopamine-lesioned rats
No full textIn order to define the role of dopamine receptors in the contralateral rotational behavior induced by caffeine in unilaterally 6-hydroxydopamine-lesioned rats, we evaluated the influence of previous exposure (priming) to dopamine receptor agonists and the effect of dopamine receptor blockade on the rotational behavior induced by caffeine. 6-Hydroxydopamine-lesioned rats received single or repeated administrations of the D1/D2 receptor agonist apomorphine (0.3 mg/kg s.c.) (primed) or vehicle (drug-naive). Three days later all rats received caffeine (30 mg/kg s.c.). Drug-naive and single-primed rats did not rotate in response to caffeine, whereas rats repeatedly primed with apomorphine rotate contralaterally. When apomorphine priming was paired to the environment (hemispherical bowls) where rats received caffeine, rotational behavior was significantly higher than that obtained in rats primed in an unpaired environment (cylinders). Repeated priming with the D2/D3 receptor agonist quinpirole (0.2 mg/kg s.c.) Induced a totally context-dependent contralateral rotation in response to caffeine, while caffeine contralateral rotation was not dependent on the context after repeated priming with the D1 agonist SKF 38393 (3 mg/kg s.c.). Caffeine context-dependent rotational behavior was antagonized by either D1 or D2 receptor antagonists SCH 23390 (0.03 mg/kg s.c.) And eticlopride (0.03 mg/kg s.c.), whereas caffeine context-independent rotation was not antagonized by SCH 23390 or eticlopride. The results show that: 1) caffeine does not induce any contralateral rotation in drug-naive 6-hydroxydopamine-lesioned rats; 2) repeated priming with a dopamine agonist enables caffeine to induce contralateral rotation; this rotation is, however, dependent on the context when D2 receptors are stimulated; 3) caffeine context-dependent contralateral rotation is counteracted by dopamine antagonists, whereas context-independent rotation is not antagonized by dopamine receptor blockad
Sensitization to the motor effects of caffeine in 6-hydroxidopamine lesioned rats is dependent from dopamine receptors
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Ruolo dei recettori dopaminergici D1 del nucleus accumbens shell nell’acquisizione della place preference indotta dalla morfina
No full textDisruption of latent inhibition in a conditioned taste aversion paradigm by D1 receptor blockade: role of dopamine in consolidation of gustatory memory traces
No full textDifferent involvement of Dopamine D1 receptor in morphine and lithium conditioned saccharin avoidance
No full textIntranigral injections of glutamate antagonists modulate dopamine D1-mediated turning behavior and striatal c-fos expression
No full textThe contribution of the substantia nigra (SN) in the positive interaction between dopamine D1 receptor agonists and glutamate antagonists was studied in rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion of dopaminergic nigro-striatal pathway. Local infusion into the SN of the 6-OHDA lesioned side of NMDA glutamate antagonists MK 801 and CPP or the AMPA antagonist NBQX at doses inducing none or minimal behavioral effects, significantly increased the turning behavior and the expression of c-fos induced, in the lesioned caudate-putamen (CPu), by a parenteral administration of SKF 38393. High doses of MK 801 or CPP infused into the SN produced intense contralateral turning per-se but induced only sparse c-fos expression in the lesioned CPu. The results show that a depression of SN pars reticulata efferent neurons, potentiates D1-mediated responses and suggest that this area may play a role in the positive interaction between glutamate antagonists and D1 receptor agonists
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