POSTSYNAPTIC ANTAGONISTIC INTERACTION BETWEEN ADENOSINE A(1) AND DOPAMINE D-1 RECEPTORS

BEHAVIOURAL and biochemical evidence for the existence of a powerful specific postsynaptic interaction between adenosine A(1) and dopamine D-1 receptors in the mammalian brain was found. Behavioural data showed that A(1) receptor stimulation induced a decrease in the D-1-induced motor activation in reserpinized mice and a decrease in the D-1-dependent oral dyskinesia in rabbits. Biochemical data suggested that A(1) receptor stimulation could produce a GTP-independent uncoupling of the rat striatal D-1 receptor to the G protein. The A(1)-D-1 receptor-receptor interaction might represent an important additional mechanism of action responsible for the motor depressant effects of adenosine agonists and for the motor stimulant effects of adenosine antagonists, like the methylxanthines caffeine and theophylline