Chronic haloperidol administration increases the density of D2 dopamine receptors in the medial prefrontal cortex of the rat

Rats received haloperidol (1.3–1.5 mg/kg/day) via their drinking water for 21 weeks. At the end of this period the density of D2 dopamine receptors and their affinity for [³H]-spiperone were measured in the striatum and medial prefrontal cortex. The chronic haloperidol treatment increased the density of D2 receptors in the striatum by 70% and in the medial prefrontal cortex by 50%. The chronic haloperidol did not significantly alter the apparent affinity of D2 receptors for [³H]-spiperone in either structure. These results indicate that the density of D2 receptors in the medial prefrontal cortex is influenced by chronic exposure to haloperidol in a manner that is very similar to the well-documented increase that occurs in the striatum.