Clin Exp Otorhinolaryngol.  2012 Sep;5(3):117-121. 10.3342/ceo.2012.5.3.117.

Decreased Immunoreactivities of the Chloride Transporters, KCC2 and NKCC1, in the Lateral Superior Olive Neurons of Kanamycin-treated Rats

• Suh MW
• Ahn SC

• KMID: 2134593
• DOI: http://doi.org/10.3342/ceo.2012.5.3.117

Abstract

OBJECTIVES
From our previous study about the weak expressions of potassium-chloride (KCC2) and sodium-potassium-2 chloride (NKCC1) co-transporters in the lateral superior olive (LSO) in circling mice, we hypothesized that partially damaged cochlea of circling mice might be a cause of the weak expressions of KCC2 or NKCC1. To test this possibility, we reproduced the altered expressions of KCC2 and NKCC1 in the LSO of rats, whose cochleae were partially destroyed with kanamycin.
METHODS
Rat pups were treated with kanamycin from postnatal (P)3 to P8 (700 mg/kg, subcutaneous injection, twice a day) and sacrificed for immunohistochemical analysis, scanning electron microscope (SEM) and auditory brain stem response.
RESULTS
The SEM study revealed partially missing hair cells in P9 rats treated with kanamycin, and the hearing threshold was elevated to 63.8+/-2.5 dB SPL (4 ears) at P16. Both KCC2 and NKCC1 immunoreactivities were more prominent in control rats on P16. On 9 paired slices, the mean densities of NKCC1 immunoreactivities were 118.0+/-1.0 (control) and 112.2+/-1.2 (kanamycin treated), whereas those of KCC2 were 115.7+/-1.5 (control) and 112.0+/-0.8 (kanamycin treated).
CONCLUSION
We concluded that weak expressions of KCC2 and NKCC1 in circling mice were due to partial destruction of cochleae.

Keyword

KCC2; NKCC1; Lateral superior olive; Kanamycin; Cochlea

MeSH Terms

Animals
Brain Stem
Cochlea
Electrons
Hair
Hearing
Injections, Subcutaneous
Kanamycin
Mice
Neurons
Olea
Rats
Symporters
Kanamycin
Symporters