Intrastriatal grafts of adrenal medulla in hemiparkinsonian rats - ultrastructural study

Abstract

The aim of the study was to investigate the ultrastructure of the right striatum after intrastriatal adrenal medulla grafts in Wistar rats with a 6-OHDA unilateral lesion of the compact part of the right substantia nigra (SN). 12 adult rats were investigated. Two rats were intact, 2 received a sham SN-lesion. Ungerstedt’s rotational test confirmed a significant lateral SN-lesion in all the animals. Two weeks after the SN lesion small samples of the adrenal medulla of 2-month old Wistar rats were prepared (0.5 mm3) and implanted stereotaxically into the middle-paraventricular region of the right striatum. The animals were perfused with 2.5 percent glutaraldehyd according to the following patern: 2 - after 1 week of survival, 2 - after 3 weeks, 2 - after 6 weeks, and 2 - after 3 months. 10 samples of ca 1 mm3 were taken from 3 regions of the right striatum (1) the region of the graft, (2) the region in the neighborhood of the graft, (3) tissue at a long distance from the transplant. Macroscopic observation showed granulomatous-like tissue at the place of the implantation of the graft after 1 week of survival. After 3 weeks and later only the evacuated cavity was observed instead of the graft. A routine electron microscopic procedure was used to expose the material in a JEM 100 B electron microscope. The study of the ultrastructure indicated many leucocytes and microglia cells in the region of the graft as well as features of destruction of the adrenal medulla cells in the rats perfused 1 and 3 weeks after transplantation. The disintegration of CA-vesicles was a prominent symptom in the adrenal cells as well as the loss of intercellular connections in the cells of the graft. The animals surviving for 6 weeks and 3 months demonstrated evident survival of dispersed singular cells with the sign of CA storage among the normal cells of the striatum, even at a long distance from the transplant. Cellular gliosis and fibrosis in the area of the graft and numerous large heterolisosomes were also visible. The ultrastructural picture suggests the possibility of even a relatively long survival of the adrenal medulla graft inside the dopaminergically denervated striatum in the form of singular cells dispersed within the striatum.