Changes of rat inner ear de novo protein synthesis in response to dexa
methasone (DEX), a synthetic glucocorticoid, have been analyzed by hig
h resolution two-dimensional sodium dodecyl sulfate polyacrylamide gel
electrophoresis (2D-SDS-PAGE) and fluorography. Two proteins (M(r) 41
000 and 35 000) were amplified and one protein (M(r) 47 000) was supp
ressed by DEX in a cochlear culture medium, In the culture medium cond
itioned by vestibular tissue, three proteins (M(r) 67 000, 57 000 and
50 000) were amplified after DEX administration. In cochlear and vesti
bular tissues, glucocorticoid-responsive protein synthesis was down-re
gulated by DEX, including two proteins (M(r) 39 000 and 35 000) in the
cochlea and five proteins (M(,) 80 000, 64 000, 59 000, 56 000 and 40
000) in the vestibule. The regulation of these inner ear proteins by
DEX suggests that glucocorticoid may play an important role in normal
inner ear microhomeostasis, as well as in the treatment of some inner
ear disorders.