Effects of Adrenal Medulla and Sciatic Nerve Co-Grafts in Rats with Unilateral Substantia Nigra Lesions

Major limitations of adrenal medulla transplantation in animal models of Parkinson's disease have been the relatively small behavioral effects and the poor or inconsistent graft survival. Transplantation of fragments of sural nerve in combination with adrenal medulla has been reported to increase the survival of chromaffin cells in adrenal medulla grafts in primates. In the present study, the possibility was tested that peripheral nerve co-grafts would increase the functional effects of adrenal medulla grafts in a 6-hydroxydopamine-lesioned rat model. Animals received unilateral substantia nigra lesions, and subsequently received intraventricular grafts of adrenal medulla, sciatic nerve, adrenal medulla plus sciatic nerve, or sham grafts consisting of medium only. Functional effects of the grafts were tested using apomorphine-induced rotational behavior. The sciatic nerve co-grafts did not increase the survival of TH-immunoreactive chromaffin cells. The co-grafting treatment also did not augment the overall effect of adrenal medulla grafts on rotational behavior. In the animals with substantial numbers of surviving chromaffin cells, however, the animals with sciatic nerve co-grafts showed greater decreases in rotational behavior as compared to the animals with adrenal medulla grafts alone, even though the number of surviving cells was not increased.