Subventricular Zone Neuroblasts Emigrate Toward Cortical Lesions

Abstract

Adult subventricular zone (SVZ) neuroblasts migrate in the rostral migratory stream to the olfactory bulbs. Brain lesions generally increase SVZ neurogenesis or gliogenesis and cause SVZ cell emigration to ectopic locations. We showed previously that glia emigrate from the SVZ toward mechanical injuries of the somatosensory cerebral cortex in mice. Here we tested the hypotheses that SVZ neurogenesis increases, that neuroblasts emigrate, and that epidermal growth factor expression increases after cortical injuries. Using immunohistochemistry for phenotypic markers and BrdU, we show that newborn doublecortin-positive SVZ neuroblasts emigrated toward cerebral cortex lesions. However, the number of doublecortin-positive cells in the olfactory bulbs remained constant, suggesting that dorsal emigration was not at the expense of rostral migration. Although newborn neuroblasts emigrated, rates of SVZ neurogenesis did not increase after cortical lesions. Finally, we examined molecules that may regulate emigration and neurogenesis after cortical lesions and found that epidermal growth factor was increased in the SVZ, corpus callosum, and cerebral cortex. These results suggest that after injuries to the cerebral cortex, neuroblasts emigrate from the SVZ, that emigration does not depend either on redirection of SVZ cells or on increased neurogenesis, and that epidermal growth factor may induce SVZ emigration.

Abnormal Neuronal Migration Changes the Fate of Developing Neurons in the Postnatal Olfactory Bulb

“…In contrast to the results gained from cortical DCX-deficient neurons, which exhibited delayed maturation rate (Ackman et al, 2009), we found that ectopic mutant neurons display anticipated maturation of their functional properties, at least for some parameters. For instance, at 7 dpe in the RMS, these injury, likely through an epidermal growth factor pathway (Sundholm-Peters et al, 2005). This emphasizes how important it is to characterize what endogenous factors modulate the migration of neuronal precursors and, thus, control cell fate.…”

Stem Cells, Their Niches and the Systemic Environment: An Aging Network

“…Analogous flexibility of stem cell progeny fate is also apparent in the brain. Normally, SVZ NSCs generate new interneurons that populate the olfactory bulb; however, upon damage to the mouse cerebral cortex, neurogenesis increases and neuroblasts migrate to the site of injury (Magavi et al 2000;Parent et al 2002;Goings et al 2004;Sundholm-Peters et al 2005). In the Drosophila ovary, each GSC normally divides asymmetrically to self-renew and to form a more differentiated cystoblast; upon GSC loss, however, the remaining GSC can divide symmetrically to generate two GSCs (Xie and Spradling 2000).…”

Surgical injury-induced early neocortical microvascular changes and characteristics of the cells populating the peri-lesion zone

“…Post-trauma neurogenesis in the brain cortex of adult mammals is given an increasing attention (Gu et al 2000, Jiang et al 2001, Jin et al 2003, Sundholm-Peters et al 2005, Ohira et al 2010. Most recent data not only evidence an influx to the traumatized region of immature neural cells from the SVZ and dentate gyrus, but also indicate to a possibility for in situ neurogenesis in the peri-injury zone.…”