Is the "lactormone" a key-factor for exercise-related neuroplasticity? A hypothesis based on an alternative lactate neurobiological pathway.

For many years lactate was seen as a metabolite from glucose metabolism. However, since the last century researchers have shown that this molecule has an important role on liver, muscle, and brain metabolism. Lactate traffics along whole body mediating many biological processes depending on specific situations. For example, glucose is the main substrate used during exercise but lactate released by striated skeletal muscle is used by own muscle as secondary fuel. On the other hand, neuronal firing in the brain is almost totally lactate-dependent. In addition, lactate has an important role on BDNF-mediated neuroplasticity. As this molecule has a pleiotropic role in the body, it was called as "lactormone" in 2009. Here we show basic concepts on peripheral and central metabolism and discuss neurobiological pathways of lactate, including an alternative hypothesis on lactate released during exercise.