Chem. Senses 26: 179-188,
2001
© Oxford University Press 2001
Immunocytochemistry of Glutathione S-Transferase in Taste Bud Cells of Rat Circumvallate and Foliate Papillae
Departments of Anatomy and 1 Department of Systems Physiology, Institute of Industrial Ecological Sciences, 2 Dentistry and Oral Surgery, School of Medicine, 3 Department of Clinical Pathology, School of Health Sciences, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan 4 Present address: Department of Physiology, Wakayama Medical College, Wakayama 641-8509, Japan
Correspondence to be sent to: Tomoko Nishino, Department of Anatomy, University of Occupational and Environmental Health, School of Medicine, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan. e-mail: 24no-tom{at}med.uoeh-u.ac.jp
Immunocytochemistry was used to investigate the distribution of cells reacting with specific antibodies against glutathione S-transferase (GST) µ and 
in rat circumvallate and foliate taste buds; the findings were confirmed 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 (iii) cells that did not react with either of these antibodies. Immunoelectron microscopy revealed that most GST subunit-immunoreactive cells seemed to be 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 buds, it seems reasonable to believe that most GST subunit-immunoreactive cells are type II cells. Whether cells immunoreactive for both PGP 9.5 and GST subunits consitute a small subpopulation of type III cells or whether they are intermediate forms between type II and III cells is under investigation. No type I cells reacted with antibodies against GST subunits in the present study. GST subunits in taste bud cells may participate in xenobiotic metabolism of certain substances exposed to taste pits, as already shown for olfactory epithelium.