Effects of chronic caffeine exposure on adenosinergic modulation of the discriminative-stimulus effects of nicotine, methamphetamine, and cocaine in rats.

Rationale: Adenosine receptors are involved in cocaine and methamphetamine discrimination and exposure to caffeine can affect behavioral effects of nicotine in rats.

Objectives: Here we investigated the relative involvement of adenosine A(1) and A(2A) receptors in nicotine, cocaine, and methamphetamine discrimination, before and/or during chronic caffeine exposure.

Materials And Methods: The nonselective adenosine receptor antagonist caffeine, the A(1)-receptor antagonist cyclopentyltheophylline (CPT), and the A(2A)-receptor antagonist MSX-3 were evaluated in rats trained to discriminate 0.

Involvement of adenosine A1 receptors in the discriminative-stimulus effects of caffeine in rats.

Rationale: Caffeine is a non-selective adenosine receptor antagonist in vitro, but involvement of different adenosine receptor subtypes, particularly adenosine A1 and A 2A receptors, in the central effects of caffeine remains a matter of debate.

Objective: Investigate the role of adenosine A1 and A 2A receptors in the discriminative-stimulus effects of caffeine.

Methods: Rats were trained to discriminate an injection of 30 mg/kg (i.

Involvement of adenosine A1 and A2A receptors in the adenosinergic modulation of the discriminative-stimulus effects of cocaine and methamphetamine in rats.

Adenosine, by acting on adenosine A1 and A2A receptors, is known to antagonistically modulate dopaminergic neurotransmission. We have recently reported that nonselective adenosine receptor antagonists (caffeine and 3,7-dimethyl-1-propargylxanthine) can partially substitute for the discriminative-stimulus effects of methamphetamine. In the present study, by using more selective compounds, we investigated the involvement of A1 and A2A receptors in the adenosinergic modulation of the discriminative-stimulus effects of both cocaine and methamphetamine.