SENSORY INATTENTION IN RATS WITH 6-HYDROXYDOPAMINE-INDUCED DEGENERATION OF ASCENDING DOPAMINERGIC-NEURONS - APOMORPHINE-INDUCED REVERSAL OF DEFICITS

Rats given intracerebral injections of 6-hydroxydopamine (6-OH-DA) that damaged the ascending dopamine-containing projection showed a syndrome of sensory inattention characterized by a failure to orient toward or otherwise investigate somatosensory, visual, or olfactory stimuli. Animals that were inattentive to those stimuli on both body sides were given apomorphine (0.05, 0.10, or 0.20 mg/kg or its vehicle, i.p.) 2, 3, 5, and 8 days after bilateral intranigral 6-OH-DA injections. At the lower two doses, apomorphine resulted in a significant restoration of orientation to all modalities of stimuli. The highest dose did not improve orientation, but only induced stereotyped sniffing behavior. The restorative effects of apomorphine administration were completely abolished by pretreatment with spiroperidol (0.05 mg/kg, i.p.). These results indicate that (i) the sensory inattention syndrome seen after intracerebral 6-OH-DA injections is a consequence of damaging dopamine-containing neurons, and (ii) the occurrence of normal-appearing sensorimotor integration requires optimal brain dopamine receptor activity. © 1979.