Immunocytochemistry of glutathione S-transferase in taste bud cells of ratcircumvallate and foliate papillae

Immunocytochemistry was used to investigate the distribution of cells react ing with specific antibodies against glutathione S-transferase (GST) mu and pi in rat circumvallate and foliate taste buds; the findings were confirme d by Western blotting. Double immunofluorescence staining for protein gene product (PGP) 9.5 and GST subunits allowed the classification of taste bud cells of both papillae into: (i) cells immunoreactive to either PGP 9.5 or GST subunit antibody; (ii) cells immunoreactive to both antibodies; and (ii i) cells that did not react with either of these antibodies. Immunoelectron microscopy revealed that most CST subunit-immunoreactive cells seemed to b e either type ii or type III cells based on their ultrastructure. Since PGP 9.5 is now widely used as a marker for type Iii cells in mammalian taste b uds, it seems reasonable to believe that most GST subunit-immunoreactive ce lls are type II cells. Whether cells immunoreactive for both PGP 9.5 and GS T subunits constitute a small subpopulation of type III cells or whether th ey are intermediate forms between type II and III cells is under investigat ion. No type I cells reacted with antibodies against GST subunits in the pr esent study. GST subunits in taste bud cells may participate in xenobiotic metabolism of certain substances exposed to taste pits, as already shown fo r olfactory epithelium.