T-588, a small molecular compound (MW 330), is developed for neurodegenerative diseases. Clinical trials of T-588 are underway in Alzheimer's senile dementia. This agent has been proven to possess neuroprotection in various studies (Ono S. et al., SFN 1998; Takuma K. et al., Eur. J. Pharm., 2000), and we also have reported that T-588 delays the progression of wobbler mouse motoneuron disease (Brain Res, 2000). Here we evaluated whether T-588 can protect motoneurons following facial nerve avulsion. The right facial nerve was avulsed at the stylomastoid foramen in Fischer 344 male rats (12-14 weeks old ). Rats drank 0.05 % T-588 solution or vehicle for 1, 3 or 4 weeks (each n= 10). During experiment, serum levels of T-588 were approximately 80 ng/ml. At 3 and 4 weeks following avulsion, the lower pons was stained with cresyl-violet. The number of facial motoneurons was counted and the survival ratio (the number of lesion side/that of non-lesion side X 100 %) was determined. At 1 week after avulsion, choline ...