The mitochondrial theory of aging suggests that mitochondria have a decrease in production capacity of adenosine triphosphate (ATP). The question may seem trivial, but it becomes more complex when considering that dysfunctional mitochondria can be eliminated by lysosomal digestion and that cell with dysfunctional mitochondria can undergo the process of apoptosis. In organs with regenerative capacity, like the liver, cell proliferation can almost completely hide mitochondrial dysfunction. However, evidence indicates selective damage in mitochondria during aging, and so the mitochondrial aging theory is gaining recognition and respect. There is solid evidence that accumulated DNA damage in mitochondria is a cause directly related to metabolic disorders such as diabetes and degenerative disorders such as Alzheimer’s disease. The central nervous system is particularly susceptible to oxidative damage due to several factors, among which are its high oxygen consumption, its dependence on aerobic carbohydrate metabolism, and its complex composition of membrane lipids. Free radicals are generated at many cell sites, and the mitochondrial respiratory chain is one of the main sources. While many studies have been conducted in experimental animal models, the results are relevant because at least some of their interventions suggest a directing aim at reducing the effects of aging.
Part of the book: Mitochondrial DNA
It has recently been discovered that the digestive tract is lined with about 100 million nerve cells; the digestive tract has been baptized, metaphorically speaking, as “the second brain,” which contains a multitude of neurotransmitters, viruses, and bacteria that help regulate our emotional state. This second brain, known as the enteric nervous system, is a unique anatomical unit that extends from the esophagus to the anus. Like the nervous system, it produces a whole series of psychoactive substances, such as serotonin, dopamine, and opioids for pain, and synthesizes benzodiazepines. In it, we find the microbiota: a set of microorganisms (viruses and bacteria). Together with the brain, the microbiota directly influences mood, character, or sleep. Knowledge about the possible relationship of the microbiota with frequent neurological diseases is still just beginning. Recently, possible changes in the microbiota have been linked to the onset of Parkinson’s disease (PD). Also, today, we know that there are differences between the microbiota of healthy people and people with multiple sclerosis and that these differences have also been related to the disease and its evolution.
Part of the book: Eat, Learn, Remember