Turning in rats following intraaccumbens shell injections of amphetamine or eticlopride.

In recent years there has been interest in possible differential behavioral functions of the core and shell subregions of the nucleus accumbens. The present study compared the effects of accumbens core and shell injections of (+)-amphetamine on turning behavior in rats; the turning effects of the selective D2 antagonist (-)-eticlopride injected into the shell were also tested. Rats (n = 28) were implanted unilaterally with guide cannulae and subsequently tested for turning in seven 20-min sessions. Amphetamine (10.0 and 20.0 microg but not 5.0 microg/ 0.5 microl) elicited contralateral turning following injection into the shell, while the same doses into the core had no effect. In animals given systemic amphetamine (2.0 mg/kg), eticlopride (10.0 but not 1.0 or 0.1 microg/0.5 microl) injected into the shell region of the accumbens produced ipsilateral turning. These results suggest that the accumbens shell, but not the core, is a critical site for turning behavior.