Changes in blood-brain barrier permeability are associated with behavioral and neurochemical indices of recovery following intraventricular adrenal medulla grafts in an animal model of Parkinson's disease.

Intraventricular adrenal medulla grafts were found to produce dissociable effects on rotational behavior induced by amphetamine and apomorphine in rats with unilateral striatal dopamine depletions. Some animals showed a decrease in the behavioral response to apomorphine, some showed a decrease to amphetamine, and some showed a decrease to both amphetamine and apomorphine. Using in vivo microdialysis, the experiments reported demonstrate that in animals with decreased rotational behavior, assessed with either amphetamine or apomorphine, there was an increase in the permeability of the blood-brain barrier to dopamine. The increased blood-brain barrier permeability was visually confirmed with horseradish peroxidase. The extent of the blood-brain barrier disruption, however, was greater in animals with a decreased response to amphetamine. Animals that exhibited decreased amphetamine-induced turning after adrenal medulla grafts also had a greater amphetamine-stimulated increase in striatal dopamine and greater extracellular striatal dihydroxyphenylacetic acid concentrations compared to controls and animals with a graft-induced decrease in the response to apomorphine. We conclude that more than one mechanism is involved in mediating the behavioral effects of adrenal medulla grafts.