Granulocyte-colony stimulating factor (GCSF) is a recently discovered neurotrophic factor that counteracts apoptosis, boosts synaptic plasticity, and, perhaps through the same mechanism, increases neurogenesis. Diederich et al (here) have an interesting study showing that the beneficial cognitive effects of training on a radial maze for 11 days and receiving daily 20 µg/kg injections of G-CSF can have synergistic effects on newborn cell survival in the dentate gyrus of rats:
The authors note in their discussion that,
A ‘use it or lose it’ principle is thought to underlie the survival of hippocampal neurons. The finding of the present study suggests that the combination of hippocampus-dependent learning and G-CSF treatment may facilitate the integration of adult-born neurons into existing neural networks and therefore insure their survival.
It is interesting to note that neurotrophins and cognitive training can have synergistic effects. In so far as rodent models are useful, this shows how important lifestyle variables like diet and education-like activities can be, because they can feed forward upon each other to at least some extent.
What is the mechanism for the synergy? That remains an open question…
Diederich K, Schäbitz W-R, Kuhnert K, Hellström N, Sachser N, et al. (2009) Synergetic Effects of Granulocyte-Colony Stimulating Factor and Cognitive Training on Spatial Learning and Survival of Newborn Hippocampal Neurons. PLoS ONE 4(4): e5303. doi:10.1371/journal.pone.0005303