[Influence of the intracaudate administration of kainic acid on the effects of the prolonged use of haloperidol and apomorphine on rats].

In rats injected with kainic acid into the dorsal part of the caudate nucleus, the chronic treatment (for 20 days) with haloperidol (1 mg/kg) did not induce hypersensitivity of dopamine receptors. However, kainic acid produced no effect on hypersensitivity of the receptors after long-term administration of apomorphine (1 mg/kg). It is suggested that in the CNS there exist at least two types of dopamine receptors one of which is involved in the hypersensitivity mechanism after long-term administration of neuroleptics (post-synaptic receptors), while another one in the hypersensitivity to the effects of long-term administration of dopaminomimetics (presynaptic receptors).