Figure 2.

Mitochondrial biogenesis-autophagy equilibrium. A delicate balance exists between the formation of new and disposal of damaged mitochondria. After a physiological stress such as starvation, autophagy is induced to clear damaged organelles (including mitochondria) and macromolecules. Concomitant activation of mitochondrial biogenesis ensures adequate ATP production and ion homeostasis. A pathological insult such as ischemia does initiate mitochondrial biogenesis; however, it is insufficient to counteract the damage, and the balance is tipped because of uncontrolled autophagy. Regulating autophagy and enhancing mitochondrial biogenesis are novel neuroprotective strategies that should receive focus in the near future.