Eugenol, like other antidepressants, increases expression of brain-derived neurotrophic factor (BDNF) gene in the hippocampus, which is necessary for an antidepressant to exhibit its activity.
In 2004 biotech firm Amgen (nasdaq: AMGN - news - people ) began trials of a Parkinson's drug called glial cell line-derived neurotrophic factor, or GDNF.