Trimethyltin intoxication induces the migration of ventricular/subventricular zone cells to the injured murine hippocampus

Abstract

Following the postnatal decline of cell proliferation in the mammalian central nervous system, the adult brain retains progenitor cells with stem cell-like properties in the subventricular zone (SVZ) and the subgranular zone (SGZ) of the hippocampus. Brain injury can stimulate proliferation and redirect the migration pattern of SVZ precursor cells to the injury site. Sublethal exposure to the neurotoxicant trimethyltin (TMT) causes dose-dependent necrosis and apoptosis in the hippocampus dentate gyrus and increases SGZ stem cell proliferation to generate new granule cells. To determine whether SVZ cells also contribute to the repopulation of the TMT-damaged dentate gyrus, 6-8 week old male C3H mice were injected with the carbocyanine dye spDiI and bromodeoxyuridine (80mg/kg; ip.) to label ventricular cells prior to TMT exposure. The presence of labeled cells in hippocampus was determined 7 and 28days after TMT exposure. No significant change in the number of BrdU+ and spDiI+ cells was observed in the dentate gyrus 7days after TMT treatment. However, 28days after TMT treatment there was a 3–4 fold increase in the number of spDiI-labeled cells in the hippocampal hilus and dentate gyrus. Few spDiI+ cells stained positive for the mature phenotypic markers NeuN or GFAP, suggesting they may represent undifferentiated cells. A small percentage of migrating cells were BrdU+/spDiI+, indicating some newly produced, SVZ- derived precursors migrated to the hippocampus. Taken together, these data suggest that TMT-induced injury of the hippocampus can stimulate the migration of ventricular zone-derived cells to injured dentate gyrus.