Differential effects on self-stimulation and motor behaviour produced by microintracranial injections of a...

Intraperitoneal injections of a dopamine-receptor blocking agent, spiroperidol, equally and severely attenuated self-stimulation in two groups of rats which either performed the motor task of licking a tube or performed the more complex task of pressing a bar in order to obtain stimulation in the lateral hypothalamus. Unilateral microinjections of 9 mug of spiroperidol into the nucleus accumbens attenuated self-stimulation without producing an apparent impairment of motor behaviour. The same injections into the corpus striatum produced an impairment of motor behaviour but self-stimulation was almost unaffected. The effect of spiroperidol on self-stimulation can therefore be dissociated from the effect on motor behaviour. These results suggests that dopamine receptors are involved in self-stimulation independently of their role in motor behaviour.