Since the discovery that the adult brain can birth new
neurons, researchers have been avidly searching for chemicals or other
treatments that can enhance the process and hopefully boost brain power. Exercise appears to have potent stimulating effects on the
growth of new neurons, as does social interaction and some drugs, such as the
antidepressant Prozac. Scientists ultimately hope that drugs developed to generate and protect new neurons will also protect against the cognitive deficits of dementia
and other neurological diseases of aging.
In a new study published today in the journal Cell, researchers screened 1000 molecules in mice to see which ones enhanced production of new neurons in a brain area involved in learning and memory. This region, known as the hippocampus, is one of two spots known to birth new neurons in the adult mammalian brain. It takes 2 to 4 weeks for the cells to migrate to the appropriate location and integrate into the existing neural circuitry, and many of them die along the way.
The researchers found that one compound, dubbed P7C3, protected
these newborn neurons from dying. When given to mice genetically engineered to
have very little new nerve cell growth, the compound seemed to repair the
abnormal hippocampus. It could also increase birth and survival of new neurons
in older rats, according to a press
release from UT Southwestern Medical Center. The animals also had improved
memory: they could better remember the location of a platform submerged in
water, a standard test of learning and memory in rodents.
Scientists are now trying to figure out how the chemical protects newly born cells. “We don’t know yet whether P7C3 can block the death of mature nerve cells, which is what occurs in humans with these conditions,” said Steven McKnight, chairman of biochemistry at UT Southwestern and senior author of the study, in the release.
According to a release from the journal Cell, where the paper was published;
Two other drugs (Dimebon and Serono compounds) - both of which bear structural similarities to P7C3 -also encourage the growth of new neurons. It’s tempting to think that all three compounds work in the same way.
In fact, Dimebon first came to the attention of researchers based on anecdotal reports by Russian physicians that the drug may ameliorate the symptoms of age-related cognitive decline. Unfortunately, unpublished reports from a phase 3 clinical trial have since failed to provide evidence that the drug could stave off the memory loss that comes with Alzheimer’s disease.
In light of the new findings, it may be worth another look. “The speculative idea that these chemicals share a common mode of action will only be rigorously tested upon identification of their molecular target(s).”