[Locomotor activity and the nucleus accumbens].

Locomotor hyperactivity in rats was induced by microapplication of apomorphine (1 microgram/microliter) or picrotoxin (0.5 microgram/microliter) bilaterally into the n. accumbens and measured in an open field test. After systemic administration, the dopaminolytic drug haloperidol in doses between 0.06 and 0.25 mg/kg abolished both types of hypermotility. After an intraaccumbens injection of haloperidol (0.4 microgram/microliter, bilaterally) or carbachol (1.0 microgram/microliter, bilaterally), the apomorphine hypermotility was completely suppressed whereas the picrotoxin effect remained unchanged. Scopolamine which is known to induce hypermotility after systemic administration was, as methylatropine (1.0 mu/microliter bilaterally), too, without any locomotor effect after intraaccumbens injection. The locomotor inhibitory effect of haloperidol is discussed to be not restricted to its dopaminolytic action within the n. accumbens.