The role of the purinergic system in the control of stereotypy: relationship to D-1/D-2 dopamine receptor activity.

A behavioral study on the stereotypy induced by caffeine and carbamazepine or caffeine and haloperidol was assessed in adult male rabbits. The stereotypy induced by caffeine + carbamazepine was not reduced by pretreatment with haloperidol (0.1 mg/kg) or SCH 23390 (0.01 mg/kg). N-ethylcarboxamidoadenosine (NECA, 0.01 mg/kg), an A2 adenosine receptor agonist, completely prevented the appearance of caffeine + carbamazepine-, but not of caffeine + haloperidol-induced stereotypy. An EEG investigation was also performed in order to evaluate the influence of the blockade of D-1 and D-2 dopamine receptors on the desynchronized tracing induced by caffeine (50 mg/kg). Neither haloperidol (0.1 mg/kg) nor SCH 23390 (0.01 mg/kg) were able to influence this EEG effect of caffeine. Present data support the hypothesis that A2 adenosine receptors may be involved in the control of pathological movements. The relationship between the purinergic system and D-1/D-2 dopamine receptors is also discussed.