We've been taught that free radicals are damaging. However, as it turns out, they regulate cellular processes that are essential to the brain's ability to adapt - at least in mice.
Researchers at the German Center for Neurodegenerative Diseases (DZNE) and the Center for Regenerative Therapies Dresden (CRTD) at TU Dresden have presented their results in the journal Cell Stem Cell.
Researchers centered on the "hippocampus," a brain region that is known to be a control center for learning and memory. New nerve cells are produced lifelong, even in adulthood.
"This so-called adult neurogenesis helps the brain to adapt and change throughout life. It happens not only in mice but also in humans," explains Prof. Gerd Kempermann, research group leader at the CRTD.
Fresh nerve cells arise from stem cells. These precursor cells are an important source for neuroplasticity, which is how we term brain capacity to adapt. The team has demonstrated in mice that neural stem cells, relative to adult nerve cells, possess a high degree of free radicals.
This is particularly true when the stem cells are in a dormant state, which ensures that they do not differentiate and grow into nerve cells. New research reveals that an increase in radical concentration makes the stem cells able to divide. Oxygen molecules serve as a switch that sets the neurogenesis in motion.
Free radicals are a byproduct of natural metabolism. Cellular processes are generally to make sure they don't pile up. This is because oxidative stress is caused by reactive oxygen molecules.
Too much oxidative stress is considered to be adverse. It can inflict nerve damage and contribute to aging processes, explains Prof. Kempermann. But clearly, this is just one element because there is also a positive side to the free radicals. In other cases, there are examples of this. What is new and shocking, though, is the fact that the stem cells in our brains not only withstand such incredibly high amounts of radicals but also use them for their work.
Radical scavengers, commonly classified as antioxidants, combat oxidative stress. These compounds are also known to be essential components of a balanced diet. They can be found in fruit and vegetables.
The beneficial impact of antioxidants has been seen to be undisputed in our research. We should also be cautious about concluding humans, based on strictly laboratory studies, says Kempermann.
Yet, the findings of the recent study at least indicate that free radicals are not inherently harmful to the brain. In fact, it is more likely that it is necessary for the brain to remain adaptable throughout life and to age in a healthier way.
