Effects of acute and subacute administration of bicuculline on dopamine and muscarinic receptors in rat brain.

The changes of characteristics of dopamine (D1 and D2) and muscarinic receptors after acute and subacute administration of bicuculline were examined in rat brain. The results demonstrated that in striatal region, the Bmax of D2 receptor was significantly increased with no change of affinity after subacute administration of bicuculline. However, neither Bmax nor Kd or the D2 receptor was changed after single administration. The characteristics of D1 receptor were not changed by either acute or subacute administration. The Bmax of muscarinic receptor in striatal area was significantly increased without changes of affinity after both a single and repeated administration of bicuculline. However, in hippocampus, the Bmax of muscarinic receptor was significantly decreased after subacute administration of bicuculline. The results suggest that the interactions among GABAergic, dopaminergic and cholinergic neuron exist in central nerve system.