Brain grafts can restore irradiation-damaged neuronal connections in newborn rats

In the present study, rat hippocampal neurones were damaged by neonatal X-ray irradiation and replaced by transplantation of normal, developing neurones of the same type. The grafted neurones (dentate granule cells) are not cholinergic or monoaminergic, but when appropriately located in the host hippocampal region they established specific and highly ordered afferent and efferent connections with the damaged host brain. Moreover, simultaneous demonstration of afferent and efferent transplant pathways showed that serial host-transplant-host connections had formed, restoring the normal neuronal circuitry initially disrupted by the irradiation. (author)