Induction of apoptosis of taste bud cells by denervation and administration of drugs

点击翻译按钮获取中文摘要

Gustatory nerve sectioning causes degeneration and disappearance of taste bud cells and after regeneration of the nerves, the taste bud cells regenerate. We recently (1996) reported that glossophaiyngeal nerve sectioning induced apoptosis of taste bud cells in the mouse circumvallate papillae. Thus, the trophic substance released from gustatory nerves, that causes differentiation and maintains taste bud cells, may have an inhibitory effect on apoptosis of taste bud cells.In this study we tried to examine the nature of the trophic substance. An immunohistochemical reaction for Bcl-2 and Bcl-x, which inhibit apoptosis, revealed positive staining of the epithelial cells in all layers of the epithelium and taste bud cells. Potassium ionophore valinomycin triggers an increase of the cytoplasinic calcium concentration. Valinomycin was injected in the mucosa near the circumvallate papillae in adult dd-mice tongues. Paraffin sections were cut and treated by method of DNA nick end labeling which detects apoptotic nuclei in situ. 20 and 24 h after injection of valinomycin, positive nuclei were scattered in the taste buds. The result shows that a rise in the intracellular content of calcium ion induces apoptosis of taste bud cells. Also we have established the method to inject the substances into the circumvallate papillae. We are examining whether apoptosis of the taste bud cells after nerve sectioning would be interfered by treatment of various kinds of growth factors such as BDNF and GDNF.