Carboplatin induces less apoptosis in the cochlea of guinea pigs than cisplatin.
BACKGROUND
Cisplatin (CDDP) is known to cause inner ear damage while carboplatin (CBDCA) induces less ototoxicity than CDDP. We examined apoptotic changes in the cochlea of guinea pigs after injection of CDDP or CBDCA using immunohistochemical and electrophysiological techniques.


METHODS
Three days after the injection of each solution, the cochleas were immunohistochemically examined for the presence of fragments of single-stranded DNA (ssDNA). The auditory brain stem response was recorded before and three days after the injection.


RESULTS
We detected fragments of ssDNA in the stria vascularis and the spiral ligament of the CDDP-treated cochlea. In this group, the threshold of the auditory brainstem response was significantly elevated, however, in the CBDCA group, no apparent change of the threshold was detected. In the CBDCA group, fragments of ssDNA were detected in the stria vascularis and the spiral ligament. The number of cells that stained positive for ssDNA, was less than that in the CDDP group.


CONCLUSIONS
Our findings indicate that CBDCA induces less apoptosis than CDDP and that this phenomenon contributes to the ototoxicity of CDDP.
Watanabe
Ken-chi
KC
Department of Oto-Rhino-Laryngology, Nippon Medical School, Tokyo, Japan. bxp02646@nifty.ne.jp
Jinnouchi
Ken
K
Hess
Alexander
A
Michel
Olaf
O
Baba
Shunkichi
S
Yagi
Toshiaki
T
D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D016190:Carboplatin / Q000009:adverse effects / Q000494:pharmacology*; D002945:Cisplatin / Q000009:adverse effects / Q000494:pharmacology*; D003051:Cochlea / Q000166:cytology / Q000187:drug effects*; D004277:DNA, Single-Stranded / Q000187:drug effects; D016057:Evoked Potentials, Auditory, Brain Stem; D006168:Guinea Pigs; D007150:Immunohistochemistry
D000970:Antineoplastic Agents; D004277:DNA, Single-Stranded; D016190:Carboplatin; D002945:Cisplatin