Exercise Increases Neural Stem Cells

Taiwan - Neural stem cells are known to exist in post-natal animals. For example, during pregnancy, an increase in mitotic cells has been reported in the brains of the mother. This has been ascribed to numerous hormones and growth factors, including prolactin and human chorionic gonadotrophin.

Furuta et al. (Gestation-induced cell proliferation in the rat brain. Brain Res Dev Brain Res. 2005 Apr 21;156(1):61-6) demonstrated BRDU positive cells in the subventricular zone of the central nervous system. It is also known that endogenous neural stem cells are inhibited by various agents, for example by inflammatory associated soluble factors.

In a recent study (Wu et al. Exercise enhances the proliferation of neural stem cells and neurite growth and survival of neuronal progenitor cells in dentate gyrus of middle-aged mice. J Appl Physiol. 2008 Sep 18) the effects of exercise on neural proliferation were examined.

The investigators sought to assess the effects of forced treadmill running on neurogenesis including

a) proliferation of neural stem cells; b) outgrowth of neurons from the progenitor cells, andc) ability of the newborn neurons to survive in the dentate area of the middle aged animals.

They found:

a) Middle age mice had much less numbers of neural stem cells and progenitor cells as compared to younger mice.

b) 5 weeks of exercise caused an augmentation in proliferation of the neural stem cells, as well as stimulated an increase in the number and viability of neurons in the middle aged mice.

c) The 5 week exercise regime caused a restoration of expression of TrkB and its ligand BDNF, which are known to be involved in endogenous neural stem cell proliferation, and area also known to decline with age.

Understanding the mechanisms by which exercise stimulates endogenous neural progenitors may lead to development of small molecule regenerative approaches.