<prompt> Schizophrenia drugs mainly act onD1 dopamine receptorsD2 dopamine receptorsD3 dopamine receptorsAch receptors  <response>: Dopamine Hypothesis states In schizophrenia, there is an imbalance of dopamine transmission with dopaminergic hyperactivity in subcoical regions but hypoactivity in prefrontal coical regions. Antipsychotics reduce psychotic symptoms by decreasing dopamine activity, their potency is highly correlated with the drugs affinity for D2 receptors. PET studies indicate that dopamine receptor antagonists are effective when approximately 80 percent of D2 receptors in the striatum are occupied. Higher occupancy rates are associated with more extrapyramidal side effectsless common with Atypical second generation Antipsychotics Reference: Page No.1491 chap.12.6 Cellular and Molecular Neuropathology of Schizophrenia P.3111 chap 31.17 First-Generation AntipsychoticsKaplan Sadocks Comprehensive Textbook of Psychiatry, 9th Edition 