It is reported that Hong Kong researchers have reviewed the causes and impacts of neurogenesis.
The two studies have linked the regrowth of key adult brain cells (neurogenesis) in two critical areas of the brain to both the benefits of exercise as a stress reducer and also to sexual behavior and reproductive issues.
"The discovery of neural stem cells in the adult brain was a spectacular event that revolutionized the traditional view that the central nervous system did not generate new neurons in adulthood," said corresponding author Dr. Kwok-Fai So of the University of Hong Kong in the People's Republic of China.
"Our research is focused on questions about the function and physiological significance of neurogenesis and what factors promote or suppress neurogenesis.
"The beneficial effects of running correlated with increased adult neurogenesis, which may provide a hint that newborn neurons could be involved in counteracting stress-related disorders.
"Research has shown that exercise can improve mood and cognition and has also demonstrated that a deficit in adult neurogenesis may result in depressive disorders. Our research is aimed at examining the relationship between exercise as a way of combating stress and the possibility that exercise may promote neurogenesis and that neurogenesis functions as the mechanism of benefit."
According to the researchers, one important adult brain area that is a 'neurogenic zone' is the hippocampus, an area involved in memory and emotional regulation. The role of new neurons in hippocampal functions "remains poorly defined," however, but they add that the effect of stress on the hippocampus is well known. Stress, especially depression and post-traumatic brain injury, have been shown to shrink the hippocampus. Recent research has shown that exercise has a link to enhancing hippocampal 'plasticity' and the regrowth of neurons - neurogenesis.
"Recent findings suggest that hippocampal neurogenesis plays a role in the beneficial effects of exercise in countering stress," they concluded.
According to the researchers, recent studies suggest adult neurogenesis in the brain's subventricular zone (SVZ), which lines the ventricles (cavities) of the brain that contain cerebrospinal fluid, plays a role in reproductive function and possibly in maternal behaviors, although the function of "SVZ neurogenesis is obscure."
They suggest that emerging evidence points to reproductive action and sexual cues, such as pheromones (known to play an important role in reproductive function), may play a role in regulating neurogenesis in the olfactory system, where the sense of smell is located, and in the SVZ. The precise contribution of newborn neurons to sexual behavior is still "under debate," the researchers point out. They cite animal studies showing that neurogenesis plays a role in female mate selection and that suppressed neurogenesis has been associated with decreased sexual performance.
"The potential importance of neurogenesis in sexual behavior, sexual cues and reproductive function has provided new insights," said So.
"These insights might provide a better understanding of sexual dysfunction, sexual disorders and normal sexual functioning," added So.
The studies have been published in the current special issue of Cell Transplantation.