Effects of adrenal medulla grafts in neonatal rat hosts on subsequent bilateral substantia nigra lesions

Abstract

Bilateral lesioning of rat substantia nigra results in a syndrome of aphagia, adipsia, and akinesia. Rats can be protected from the development of this syndrome if they have previously received intraventricular fetal substantia nigra grafts as neonates. In this experiment, we determined whether neonatal adrenal medulla grafts would offer similar protection. One day old Sprague-Dawley rat pups received bilateral intraventricular allografts of either adrenal medulla or sciatic nerve from adult donors. At 3-4 months of age the rats received bilateral lesions of the substantia nigra with 6-hydroxydopamine. After lesioning, food and water consumption were greater in the rats receiving adrenal medulla grafts, as compared to the sciatic nerve control group. Nevertheless, food and water consumption was markedly decreased in both groups, and activity levels did not differ between the two groups. Histology showed consistently surviving grafts with large numbers of surviving catecholamine-containing cells. Thus adrenal medulla grafts in neonatal hosts offer partial protection against the syndrome of adipsia and aphagia produced by subsequent substantia nigra lesions, but this protection is much less than that produced by substantia nigra grafts.