INTRAACCUMBENS IMPLANTS OF EMBRYONIC DOPAMINERGIC-NEURONS REVERSE THE BEHAVIORAL SUPERSENSITIVITY TO OPIATES EVOKED BY LESION OF THE MESOLIMBIC DOPAMINERGIC PATHWAY

The ascending mesotelencephalic dopaminergic systems of rat pups of 3 days of age were bilaterally lesioned using 6-hydroxydopamine injected at the level of the lateral hypothalamus. A sub-group of lesioned pups received, 5 days after the lesion, a dopamine neuron-rich cell suspension graft implanted bilaterally into the striatum and nucleus accumbens. Behavioral tests were conducted 6 months later. The lesion induced an increase in the locomotor activation induced by d-Ala2-Met5-enkephalinamide injected into the nucleus accumbens (2.5 μg/side) as compared to the activation observed in control animals. Locomotor activation by systemic apomorphine (0.1 mg/kg s.c.) was also increased while that induced by amphetamine (1.5 mg/kg i.p.) was abolished. The presence of DA neuron implants reversed each of these post-lesion modifications. © 1990.