Does treatment with haloperidol for 3 weeks produce depolarization block in midbrain dopamine neurons of unanaesthetized rats?

Treatment of rats with haloperidol, 0.5 mg/kg SC daily for 3 weeks, did not increase the concentration of dopamine in the dopamine-rich nuclei of the forebrain apart from a small effect in the olfactory tubercle. Cessation of the nerve impulse flow in the ascending dopamine neurons induced by gamma-butyrolactone caused an approximately twofold increase in the dopamine levels of both haloperidol-treated and control rats. The results are hard to reconcile with the notion of haloperidol-induced depolarization block, i.e., cessation of impulse flow in the majority of midbrain dopamine neurons of unanaesthetized rats.