Study of the gerbil utricular macula following treatment with gentamicin, by use of bromodeoxyuridine and calmodulin immunohistochemical labelling.
Effects of ototoxic drugs on the gerbil vestibular sensory epithelium were probed by use of immunocytochemical labelling with antibodies to both a mitogenic marker (bromodeoxyuridine) and a hair cell specific protein (calmodulin). Nine animals had gentamicin administered once daily for 5 days, as a transtympanic injection into the right middle ear. They additionally were given a daily intraperitoneal injection of bromodeoxyuridine, starting on the same day as the gentamicin injection and continuing until the day of sacrifice. Nine other animals, serving as controls for bromodeoxyuridine incorporation, received only the intraperitoneal injections of bromodeoxyuridine. The inner ears from three gerbils were obtained at 1, 2 or 4 weeks following the last gentamicin injection and utricles from the injected ears were processed for immunohistochemical analysis. In specimens where gentamicin was administered, we found evidence of bromodeoxyuridine incorporation in 17 cells (10 single cells and 7 pairs of cells) in a total of 216 sections taken from the central regions of the 9 utricles. However, in control specimens, no bromodeoxyuridine labelling was found in any cells of the 216 sections examined. Of 10 single cells labelled with bromodeoxyuridine, two cells in the hair cell layer were labelled with antibodies against calmodulin. One had a faint labelling in the nucleus and the other in the stereocilia, but not in the cell bodies. Of 7 pairs of cells, two pairs with nuclei localized in the hair cell layer had faint labelling for calmodulin in the nuclei, but no labelling in any other part of the cell. The other 13 cells labelled with antibodies to bromodeoxyuridine were not labelled with antibodies to calmodulin. Our results suggest that the bromodeoxyuridine-labelled cells could not be positively identified as hair cells based on immunohistochemical labelling for calmodulin.
Ogata
Y
Y
Department of Otolaryngology, Yamaguchi University School of Medicine, Ube, Japan. yoichi-o@po.cc.yamaguchi-u.ac.jp
Slepecky
N B
NB
Takahashi
M
M
D008267:Acoustic Maculae / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D005839:Gentamicins / Q000633:toxicity*; D005849:Gerbillinae; D018069:Hair Cells, Vestibular / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D012038:Regeneration / Q000502:physiology; D013997:Time Factors
D002147:Calmodulin; D005839:Gentamicins; D001973:Bromodeoxyuridine