Led by Dr. Zahoor A. Shah, Dr. Shadia E. Nada and Jatin Tulsulkar (graduate student), researchers at the University of Toledo, Toledo, OH, have discovered that mice treated with Ginkgo biloba 4 hours after inducing experimental stroke and then daily for seven days had improved recovery and less brain damage than the control mice. It was also observed that Ginkgo biloba-treated mice had enhanced neurogenesis, partly due to the increased protein expression of hemeoxygenase 1, an antioxidant gene that also has a role in neurogenesis. Pertinently, mice lacking the hemeoxygenase 1 gene were observed to have reduced neurogenesis after stroke.
Besides prevention, improving recovery following a stroke should become the prime focus of current stroke research. We now know that neurogenesis is not only an ongoing process in adults, but can also be induced by pathological conditions like traumatic brain injury and ischemic stroke, and strategies that promote endogenous neurogenesis as part of repair and regeneration process should be prioritized. Neurogenesis in the adult brain involves not only the proliferation and migration of precursor cells known as stem cells/neural progenitor cells (NSCs) but also their functional integration into the neural network. Ischemia, though a potent inducer of proliferation and migration of NSCs, does not provide an environment conducive to their survival, differentiation and integration, and creating an environment with exogenous drugs is paramount to improving the number of NSCs that can result in improved brain repair and regeneration.
The study, first reported in Molecular Neurobiology (Vol. 49, 2014) and then reviewed in Neural Regeneration Research (Vol. 9, No.11, 2014), confirmed that Ginkgo biloba, in addition to its antioxidant, neuritogenic and angiogenic properties, provides a conducive environment for the survival and functional integration of NSCs into neural system.
"Controversies and other ethical issues related to stem cell therapies make drug-induced enhanced neurogenesis a promising treatment strategy," stressed senior author Zahoor A. Shah. "Besides one documented clinical trial recommending the use of Ginkgo biloba after ischemic stroke, further high quality and large-scale randomized controlled trials are warranted to test its efficacy in stroke recovery" he said.