Neurogenesis in Adult Mammalian Hippocampus after Ischemia: Rodent versus Primate Models

The adult mammalian hippocampus harbors neural precursor cells capable of generating glial and neuronal cells. Their existence was demonstrated in both non-primate mammals and primates including humans, and recently has attracted a significant scientific interest focused on the precursor cell potential to replace lost brain cells. Proliferation and differentiation of hippocampal progenitors are affected by brain injury and are regulated by a variety of molecular signals. Brain ischemia is a major activator of these precursors as demonstrated by experimental models in rodents and monkeys. In rodent hippocampal formation, ischemia increases neurogenesis and gliogenesis in both dentate gyrus and cornu Ammonis. In monkeys, however, ischemia was unable to trigger production of new neurons in cornu Ammonis, while in dentate gyrus postischemic progenitor cell activation was at lower levels than in rodents. Thus, rodents and primates appear to differ in their precursor cells’ ability to perform neurogenesis. Unraveling the molecular machinery responsible for this interspecies discrepancy might reveal novel strategies to manipulate neural precursors for therapeutic purposes in humans. Biomed Rev 2005; 16: 1-11.