8 (3 chlorostyryl)caffeine Adenosine Amphetamines Animalia Animals Caffeine Catalepsy Corpus Striatum Dopamine Antagonists Enkephalins Gene Expression Haloperidol Mice Mice, Inbred C57BL Mice, Knockout Motor Activity Phenethylamines RNA, Messenger Receptor, Adenosine A2A Receptors, Dopamine D1 Receptors, Dopamine D2 Receptors, Purinergic P1 adenosine A2a receptor adenosine A2a receptor agonist adenosine A2a receptor antagonist adenosine receptor blocking agent amphetamine derivative animal behavior animal experiment animal model