Hypophysectomy does not block sensitization to the dopamine agonist quinpirole or its modulation by the MAOI clorgyline

Repeated administration of the dopamine agonist quinpirole induces behavioral sensitization in rats that is characterized by a four- to eight-fold increase in the amount of locomotion compared to an acute dose of quinpirole, in the absence of any increases in mouthing behavior. The monoamine oxidase (MAO) inhibitor, clorgyline, switches behavioral sensitization to quinpirole from that of locomotion to self-directed mouthing. The mechanism by …