Non-chromaffin tissue plus nerve growth factor reduces experimental parkinsonism in aged rats

The mechanisms by which intrastriatal grafts of chromaffin tissue alleviate the signs of clinical and experimental parkinsonism remain elusive. In the present report, we have demonstrated that, in conjunction with intraventricular infusion of nerve growth factor (NGF), ventricular grafts of either non-chromaffin or adrenal medullary tissue are equally effective in reducing apomorphine-induced circling in rats whose substantia nigra have been permanently lesioned with 6-hydroxydopamine. These treatments were much more effective than implantation of adrenal medulla without NGF. In addition, the effects persisted indefinitely, though at a reduced level, after discontinuation of the NGF infusion. The results suggest that trophic factors may be crucial to the beneficial effects of intracerebral transplanted tissues.