Striatal dopaminergic synapses In drug-naive versus haloperidol-treated schizophrenic patients

Aim of the present study was the simultaneous analysis of striatal DAT and D₂-receptor in first-episode drug-naive compared to haloperidol treated schizophrenic patients with a new SPECT-ligand to the DAT. With a combined protocol for a 99mTc-TRODAT-1/123I-IBZM-SPECT, we analyzed 10 first-episode never-treated compared to 10 haloperidol-treated inpatients with a diagnosis of schizophrenia according to DSM IV/ICD-10 criteria. We found a significant difference of the specific TRODAT-1-binding to the presynaptic DAT in the drug-naive compared to the haloperidol-treated patients (p=0.005), and of the specific post-synaptic D2-receptor-binding of IBZM (p<0.0001). Both patient groups did not differ significantly with respect to age, gender, height, weight, handedness, duration of illness, and psychopathology with exception of EPMS signs. Our results indicate that haloperidol-treatment not only affects radioligand binding to the striatal post-synaptic D2-receptor, but involves the presynaptic DAT, too.