, 2006), when we found the protein levels of GluR1

to have returned to control levels. There is evidence, however, of increased GluR1 mRNA expression after 3 and 7 days of voluntary exercise (Molteni et al., LDK378 price 2002). Nonetheless, Chen et al. (2007) have demonstrated that voluntary and forced exercise may activate distinct signaling pathways, which could explain the different findings between voluntary exercise (Molteni et al., 2002) and the present protocol. During development, GluR1 and GluR2 are related to increases of length and complexity of dendritic arborizations (Chen et al., 2009). This doesn’t appear to be a mechanism involved in the changes that occur in the adult brain and the ones observed here, as we noticed increases of MAP2 and NF68 after exercise despite the decreased levels of GluR1 and unaltered levels of

GluR2/3. MAP2 is an early and sensitive marker of neuronal damage following traumatic brain injury (Huh et al., 2003), and has not yet been associated with exercise-dependent plasticity. Increased levels of MAP2 mRNA in the granule cell dendrites have been associated with the induction of LTP in hippocampal perforant path/granule cell synapses in rats (Roberts et al., 1998) and with some forms of hippocampus-mediated memory processes (Fanara et al., 2010). On the other hand, decreased levels of MAP2 and NFs have been associated with hypercortisolism (Cereseto et al., 2006). Our findings revealed increases of MAP2 protein and mRNA, together with increased MK0683 cell line immunoreactivity and levels of NF68. To the best of our knowledge, this is the first evidence of changes of protein levels of NFs and MAP2 in response to exercise, despite reports of increased dendritic

length (Stranahan et al., 2007) and complexity (Eadie et al., 2005). Together with previous literature, the present data can be interpreted as a beneficial plastic effect. In fact, increased perikaryal levels of NF proteins are thought to be neuroprotective in diseases such as amyotrophic lateral sclerosis, due to NF association to calcium-binding proteins (for a review, Cyclic nucleotide phosphodiesterase see Julien, 1999). It is noteworthy, however, that the increase of MAP2 preceded the increase of MAP2 mRNA, whereas no NF mRNA has changed after exercise. Changes of protein levels in the absence of mRNA changes may be explained by protein accumulation due to increased protein stability and/or decreased protein degradation, which also applies to SYN and GFAP data. Exercise-induced astrocytic changes have also been previously reported. It was observed that astrocytic density and GFAP levels increase in the cortex and striatum after 3 and 6 weeks of treadmill exercise (Li et al., 2005). In the SGZ, GFAP-expressing cells increase after 7 days of wheel running (Komitova et al., 2005).