ACTIVITY OF INTRASTRIATAL NIGRAL SUSPENSION IMPLANTS AS ASSESSED BY MEASUREMENTS OF DOPAMINE SYNTHESIS AND METABOLISM

Abstract

The activity of intrastriatal grafts of nigral cell suspensions was monitored biochemically, using radioenzymatic assay of dopamine [DA] its major acidic metabolite, DOPAC [3,4-dihydroxyphenylacetic acid] and dopa accumulation after dopa decarboxylase inhibition. Implants of 4-9 .mu.l of nigral cell suspension restored striatal DA levels by an average of 13-18%, with the highest individual values reaching .apprx. 50% of control. DOPAC was restored from .apprx. 5% in the lesioned controls to .apprx. 20% of normal in the grafted rats. The DOPAC:DA ratios and the dopa accumulation measures indicated that the grafted DA neurons were spontaneously active and that the transmitter turnover rate was on the average some 50-100% higher than the intact intrinsic nigrostriatal DA neurons. The intrastriatal nigral suspension grafts are capable of restoring dopaminergic neurotransmission in the previously denervated striatum.