Abstract: Objective To determine the neurogenesis in injured fimbria fornix (FiFx).Methods The left fimbria fornix of SD rat ( EM>n/EM> =7) were subjected to transection followed by intraperitoneal injection of 5-bromo-2-deoxy-uridine (BrdU). Coronal sections through hippocampus were stained with Nestin and BrdU antibodies 7 days after operation. The normal and injured FiFx were dissociated for neural stem cell specific culture 7 days post transection. Immunofluorescence staining was used to determine the properties of the neurospheres.Results Immunofluorescence revealed that Nestin-expressing cells were present in FiFx following lesion. Majority of Nestin positive cells were also positive for BrdU, a marker of DNA synthesis. Nestin positive proliferative cells were almost entirely absent from unlesioned tissue. Neurospheres cultured in vitro from lesioned FiFx displayed the characteristics of neural stem cells (NSCs) proliferation, expression of embryonic markers, and multipotential differentiation into neurons, astrocytes and oligodendrocytes. Conclusion These results demonstrate that transection of the tracts related with hippocampal function can stimulate NSCs proliferation in the projection pathways themselves. Ectopic neurogenesis in FiFx may provide an additional mechanism for repair of innervation following damage.

Key words: Fimbria fornix, Neural stem cell, Neuron, Transection, Cell culture, Immunofluorescence, Rat