"There was a profound behavioral effect of the treatment, even after it 'washed out' of the system," Dr. Eckman notes. "This shows that the treatment affects the underlying pathology."
Several previous studies point to the possibility that drugs like pramipexole and ropinirole might modify the course of PD, but this effect is difficult to test and has never been proven, says Dr. Eckman. While these drugs are useful in treating the symptoms of PD, they have not been designed to prompt development of new neurons, he adds. Altering how the current drugs work or developing new compounds to enhance neurogenesis could provide an entirely new avenue for treating this disease.
"These findings are very exciting for several reasons. Being able to stimulate endogenous stem cells in patients would alleviate the need for transplantation of engineered cells, and as a drug therapy, it would be also easy to administer to patients. Moreover, given that similar drugs exist, medicinal chemistry to maximize this effect could be achieved quickly," says Diane Murphy, Ph.D., the NINDS program director for the grant that funded this research.
Dr. Eckman and Dr. Van Kampen are now looking at how different doses of pramipexole and similar drugs affect neurogenesis. Once they identify the most effective doses in animals, researchers might be able to test comparable doses in humans. They are also carrying out experiments to learn if using drugs that act on other kinds of receptors might stimulate neurogenesis in Alzheimer's disease and other neurodegenerative diseases.