FETAL NIGRAL CELL-SUSPENSION GRAFTS INFLUENCE DOPAMINE RELEASE IN THENON-GRAFTED SIDE IN THE 6-HYDROXYDOPAMINE RAT MODEL OF PARKINSONS-DISEASE - IN-VIVO VOLTAMMETRIC DATA

The present study employed differential-pulse voltammetry to assess th e influence of foetal ventral mesencephalic grafts on dopamine overflo w in the contralateral caudate putamen of the B-hydroxydopamine rat mo del of Parkinson's disease. The experimental design involved measureme nts of dopamine overflow in the grafted and contralateral striatum. Co ntrol measurements of dopamine overflow were performed in 6-hydroxydop amine-lesioned rats only and the caudate putamen of normal control rat s. Cell suspensions of foetal rat ventral mesencephalic tissue were gr afted into the dopamine-depleted caudate putamen of unilaterally 6-hyd roxydopamine-lesioned rats. At 6 weeks, animals with functional, matur e grafts (as assessed by amphetamine-amplified behavioural asymmetry), were pretreated with pargyline (75 mg/kg i.p.), and both striatal sid es were monitored for dopamine overflow for 90 min following amphetami ne sulphate administration (5 mg/kg i.p.). The time course of dopamine overflow inside the graft was similar to that in the contralateral ca udate putamen of the same animal, the normal control animal and the co ntralateral caudate putamen of 6-hydroxydopamine-lesioned animals. How ever, in grafted animals the mean dopamine overflow detected in the co ntralateral caudate putamen was approximately 34% lower than the conce ntration of dopamine detected in the contralateral caudate putamen of 6-hydroxydopamine-lesioned control animals and approximately 39% lower than the concentration of dopamine detected in the caudate putamen of the normal control animal. There was no statistical difference in the concentration of amphetamine-induced dopamine overflow between the ca udate putamen contralateral to the 6-hydroxydopamine lesion and the ca udate putamen of the normal control animal. These data suggest that in trastriatal foetal ventral mesencephalic suspension grafts reduce amph etamine-induced dopamine release in the contralateral non-grafted caud ate putamen.