M. Okada et al., DETERMINATION OF THE EFFECTS OF CAFFEINE AND CARBAMAZEPINE ON STRIATAL DOPAMINE RELEASE BY IN-VIVO MICRODIALYSIS, European journal of pharmacology, 321(2), 1997, pp. 181-188
The effects of carbamazepine and caffeine on adenosine receptor subtyp
es were determined using in vivo microdialysis in an attempt to elucid
ate their different psychotropic mechanisms of action. Adenosine and a
selective adenosine A(1) receptor agonist decreased the striatal extr
acellular dopamine level, whereas caffeine, carbamazepine and a select
ive adenosine A(1) receptor antagonist increased it, but neither an ad
enosine A(2) receptor agonist nor an antagonist affected it. Under con
ditions of adenosine A(1) receptor blockade, adenosine, carbamazepine
and a selective adenosine A(2) receptor agonist increased the striatal
extracellular dopamine level, whereas caffeine and a selective adenos
ine A(2) receptor antagonist decreased it. These results suggest that
adenosine A(1) receptor stimulation reduces the striatal extracellular
dopamine level, and that adenosine A(2) receptor stimulation under co
nditions of adenosine A(1) receptor blockade increases it. Therefore,
caffeine is an antagonist of both adenosine A(1) and A(2) receptor sub
types, and carbamazepine is an adenosine A(1) receptor antagonist as w
ell as an adenosine A(2) receptor agonist. These properties support th
e hypothesis that the central actions of both carbamazepine and caffei
ne result from effects on both adenosine A(1) and A(2) receptors.