The effect of molindone on the activity of dopaminergic (DA) neurons in the rat 
midbrain and on DA metabolism in the striatum and olfactory tubercles was 
studied using extracellular single unit recording and biochemical techniques 
respectively. Molindone in low intravenous doses (0.4-0.8 mg/kg) was found to 
reverse d-amphetamine and apomorphine induced depression of DA neurons and to 
block apomorphine induced depression of these cells. Molindone was also found to 
increase dopamine synthesis and dihydroxyphenylactic acid levels in the striatum 
and olfacotry tubercles. In all of these respects molindone behaves identically 
to most classical neuroleptics. However, unlike most antipsychotic drugs 
previously tested, molindone failed to increase the baseline firing rate of DA 
cells and blocked haloperidol induced increases in DA neuron activity. In this 
regard molindone most closely resembles thioridazine and clozapine. Possible 
mechanisms of action of molindone are discussed based on these findings.