Hippocampus neurogenesis

Another source of evidence supporting the neurotrophic hypothesis of depression comes from studies of the direct effects of BDNF on emotional regulation. Direct infusion of BDNF into the midbrain, hippocampus, and lateral ventricles of rodents has an antidepressant-like effect in animal models. Moreover, all known classes of antidepressants are associated with an increase in BDNF levels in animal models with chronic (but not acute) administration. This increase in BDNF levels is consistently associated with increased neurogenesis in the hippocampus in these animal models. Other interventions thought to be effective in the treatment of major depression, including electroconvulsive therapy, also appear to robustly stimulate BDNF levels and hippocampus neurogenesis in animal models. 

Brandt MD, Jessberger S, Steiner B, Kronenberg G, Reuter K, Bick-Sander A, Von deer Behrens W, Kempermann G (2003) Transient calretinin-expression defines early postmitotic step of neuronal differentiation in adult hippocampus neurogenesis of mice. Mol Cell Neurosci 24 603-613. 

The discovery of neurogenesis in certain areas (e.g., the hippocampus) of the adult brain represents a new departure from our conventional view of this organ... 

The total human complement of neurons is laid down around birth, and if they die they cannot be replaced - unlike most cells in our body. However, this central dogma of neuroscience has been challenged by the recent finding that neurogenesis can occur in the adult rat hippocampus, and these new cells seem to be required for at least one type of memory (Shors et al., 2001). Whether this will also be the case in... 

Lee, J., Duan, W. and Mattson, M. P. Evidence that brain-derived neurotrophic factor is required for basal neurogenesis and mediates, in part, the enhancement of neurogenesis by dietary restriction in the hippocampus of adult mice. /. Neurochem. 82 1367-1375, 2000. 

Clearance of outdated memory in the hippocampus — a role for adult neurogenesis 871... 

Clearance of outdated memory traces in the hippocampus —a role for adult neurogenesis What happens... 

The proposed neurogenesis-memory clearance hypothesis is attractive because addition and removal of adult-born neurons in local network architecture could gradually destabilize the stored memory traces. Also, adult-generated neurons within the dentate gyrus, the upstream location in the hippocampus, potentially can amplify the destabilization effects. Coincidently, these newborn neurons are short-lived, typically with a life-span of three weeks in rodents [40], which seems to correlate well with the duration of hippocampal dependence of declarative memories. 

Another level of cellular adaptation to psychotropic drug exposure involves the change in neuronal number through neurogenesis. Recent research has demonstrated that in the adult hippocampus, new cells constantly arise from immature neural precursor cells in the subgranular zone of the dendate gyrus, migrate into... 

Malherg J.E., Eisch A.J., Nestler E.J., and Duman R.S. (2000) Chronic antidepressant treatment increases neurogenesis in adult rat hippocampus. / Neurosci 20(24) 9104-9110. 

L., Pasinetti, G.M., Shioi, J., Robakis, N.K., Elder, G.A. (2002). Overexpression of wild type but not an FAD mutant presenilin-1 promotes neurogenesis in the hippocampus of adult mice. Neurobiol Dis, 10, 8-19. 

There are, however, controversies and debates over the involvement of the hippocampus and adult neurogenesis in the etiology of depression. Among them, i) a link between... 

All these data involved the hippocampus, a structure traditionally involved in learning and memory, and adult neurogenesis in depression and anxiety disorders (Thomas and Peterson, 2003). Antidepressant treatments may increase neural plasticity and adult neurogenesis, especially in the hippocampus. However, the neurogenic theory of depression remains the source of debate and controversy, and requires further study (Feldmann et al.,... 

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