EXPRESSION OF C-FOS MESSENGER-RNA AND C-FOS PROTEIN IN NEOCORTICAL TRANSPLANTS PLACED INTO EXCITOTOXIN-INDUCED LESIONS IN ADULT-RATS

Using anatomical and electrophysiological methods, previous studies fr om this laboratory demonstrated that fetal neocortical block transplan ts placed into the excitotoxically ablated cortex of adult rats can es tablish functional connections with the host central nervous system. I n order to further examine functional integration at the level of geno mic activation/molecular signaling systems, transplants were analyzed for the presence of c-fos mRNA and Fos protein-labeled cells following a 20-min exposure of the animal to a novel open-field environment, Th is behavioral testing paradigm, which previously was shown to induce e xpression of c-fos mRNA in several brain regions including the sensori motor cortex, was administered at 3 months after grafting. The transpl ants were found to express c-fos mRNA as well as c-fos protein followi ng novelty exposure. These labeled cells were distributed primarily al ong the peripheral margin of the grafts. This study therefore suggests that at least some neurons within transplants become integrated with the host pathways at the level of molecular signal transduction. (C) 1 994 Academic Press, Inc.