Early Neural Grafts Transiently Reduce the Behavioral Effects of Radiation-Induced Fascia Dentata Granule Cell Hypoplasia

摘要

It is possible to produce selective hypoplasia of the hippocampal granule cellsby X-irradiating the partially shielded rat brain. Specificity of damage is assured by conducting the radiation exposure when fascia dentata granule cells are mitotic, but adjacent neurons are mature (and therefore less radiosensitive). This brain damage effectively disrupts major afferents to the hippocampus by eliminating the target cells of the perforant path (from entorhinal cortex). Thus, although the lesion is discrete, it often produces behavioral consequences similar to hippocampectomy. Bayer et al., for example, described locomotor hyperactivity, reduced spontaneous alternation in a T-maze and retarded acquisition of a passive avoidance task in rats with early radiation-induced damage of the fascia dentata. More recently, we replicated and extended this work by revealing that rats with hypoplasia of the fascia dentata granule cells also exhibit perseverative spontaneous turning and that behavioral deficits change significantly over time.