Locomotor behavior changes induced by E-17 striatal transplants in normal rats

It is well established that embryonic tissue transplantation into an abnormal or lesioned brain can ameliorate some of the accompanying symptomotology. Specifically, transplants placed into kainic acid (KA) or ibotenic acid lesioned striatal rats promote behavioral recovery in various ambulatory measures. In the KA animal model, when the transplant encroached on normal host tissue, the behavioral recovery was diminished. However, little has been done to reveal what effect tissue transplants have on normal host brain. The present study placed E-17 striatal tissue into a normal adult striatum. Digiscan locomotor testing revealed that ten weeks after surgery, the implanted animals demonstrated pervasive nocturnal hyperactivity. Ambulatory, vertical and stereotypic measures were significantly increased when compared to controls. Rats with ten week implants showed lower increases in body gain yet increased food consumption when compared to controls. The transplants survived and contained normal looking AChE positively stained neurons. Evidence for fiber passage through the host-graft interface was also seen. When comparing three and ten week implants, there was a decrease in transplant size in the latter group accompanied by enlarged ventricles giving the brain a lesioned-like appearance. From these results, it is suggested that the placement of E-17 striatal tissue into adult striatum results in lesion-like behavior which may be attributed to the physical disruption of striatal systems.