Reinnervation of the nucleus accumbens and frontal cortex of the rat by dopaminergic grafts and effects on hoarding behavior.

Embryonic dopaminergic neurons were implanted in the form of a cellular suspension in the nucleus accumbens previously deprived of its dopaminergic innervation by a local injection of 6-hydroxydopamine. The graft provided a dopaminergic reinnervation to the nucleus accumbens, the anteromedial striatum, the anteromedial frontal cortex and also, in some cases, of the septum. The pattern of reinnervation was specific for each structure and similar to the innervation provided by mesocorticolimbic dopaminergic neurons to these same structures in the normal animal. The graft restored the locomotor stimulatory action of amphetamine which was abolished in the lesioned controls. Hoarding behavior, which was disrupted following the lesion, was not reinstated by the graft alone. However, if the grafted neurons were stimulated by a small dose (0.2 mg/kg, i.p.) of (+)-amphetamine, hoarding reappeared in the grafted animals, while the same dose of amphetamine had no effect in the lesioned controls.