Expression of glial cell line-derived neurotrophic factor (GDNF) and GDNF family receptor α1 in mouse taste bud cells after denervation

Glial cell line-derived neurotrophic factor (GDNF) has been isolated as a neurotrophic factor that affects the survival and maintenance of central and peripheral neurons. Using immunocytochemical methods, we examined whether the taste bud cells in mouse circumvallate papillae after transection of the glossopharyn-geal nerves expressed GDNF and its receptor, GDNF family receptor α1 (GFRα1). By 5 and 10 days after denervation, the number of taste buds had decreased markedly; however, the remaining taste bud cells still expressed GDNF and GFRα1. By 14 days after denervation, most of the taste buds had disappeared and GDNF- and GFRα1-immunoreactive cells were not seen. By 4 weeks after denervation, numerous TrkB-immunoreactive nerve fibers had invaded the papilla and a few taste buds expressing GDNF and GFRα1 had regenerated. Thus, GDNF- and GFRα1-immunoreactive taste bud cells after denervation vanished following the disappearance of the taste buds and reappeared at the same time as the taste buds reappeared.