Neuronal precursors of the adult rat subependymal zone persist into senescence, with no decline in spatial extent or response to BDNF

Abstract

The adult mammalian brain continues to harbor ependymal/subependymal zone (SZ) precursor cells, which can give rise to neurons in vitro. In adult rats, explants of the rostral 6–7 mm of the SZ give rise to neurons in vitro, and over this entire expanse, neuronal survival is supported specifically by brain‐derived neurotrophic factor (BDNF). We asked whether either the (a) spatial distribution, (b) abundance, or (c) BDNF responsiveness of the neuronal precursor population was affected by age. Explants of three rostrocaudally defined regions were taken from both young and old rats (3 and 20 months old, respectively), and cultured in 2% fetal bovine serum‐containing media with or without added BDNF (20 ng/mL). The extent of neuronal production by these explants varied only minimally with their level of derivation, such that substantial outgrowth was observed at each level tested. Neuronal outgrowth was marginally higher and more rapid in achieving its maximal extent in the 3‐month‐old rats compared with their aged counterparts, but neuronal outgrowth was robust at each age tested. The duration of survival of SZ‐derived neurons did not differ between the young and old rats. At both ages, BDNF supported the survival of these new adult neurons. The extent of BDNF's influence was independent of both the age of the donor rat and the rostrocaudal level at which the parent SZ explant was taken. Thus, the neuronal precursors of the rat brain persist into senescence; the size of the precursor pool attenuates minimally with age, and its spatial extent remains constant. The neurons generated from these precursors can respond to BDNF throughout life. © 1997 John Wiley & Sons, Inc. J Neurobiol 32: 554–566, 1997

cAMP Response Element-Binding Protein Regulates Differentiation and Survival of Newborn Neurons in the Olfactory Bulb

“…10 B). Interestingly, several studies have demonstrated that the olfactory input modulates the expression of molecules, such as tenascin-R (Saghatelyan et al, 2004) and BDNF (McLean et al, 2001), that promote migration, differentiation, and survival of neuronal precursors arising from the SVZ (Kirschenbaum and Goldman, 1995;Goldman et al, 1997;Gascon et al, 2005).…”

Neuronal regeneration: Lessons from the olfactory system

“…92 In these experiments, BDNF appeared to enhance initial neuronal differentiation but not survival: proliferation of cells in the spheres was not affected by BDNF, and the BDNF-stimulated increase in neuron number did not persist at longer culture times. 92 However, other investigators have reported that BDNF does promote survival of neurons in SVZ explant cultures isolated from adult rats; 93,94 NGF and NT-3, however, do not appear to have this effect. 93 BDNF appears to have effects on SVZ-derived neurons in vivo as well.…”

Spatial memory performances of aged rats in the water maze predict levels of hippocampal neurogenesis

“…Thus, it has been shown that hippocampal neurogenesis declines with increasing age (11,(19)(20)(21)(22), and this process is related to a decline in proliferative activity rather than to a general change in metabolic conditions or an alteration of the survival of the newly born neurons (8,(19)(20)(21)23). However, whatever the role of these various relationships, a quantitative correlation between neurogenesis and performance still has not been demonstrated in a hippocampal-dependent test (24).…”