Selective vulnerability of adult cochlear nucleus neurons to de-afferentation by mechanical compression.
It is well established that the cochlear nucleus (CN) of developing species is susceptible to loss of synaptic connections from the auditory periphery. Less information is known about how de-afferentation affects the adult auditory system. We investigated the effects of de-afferentation to the adult CN by mechanical compression. This experimental model is quantifiable and highly reproducible. Five weeks after mechanical compression to the axons of the auditory neurons, the total number of neurons in the CN was evaluated using un-biased stereological methods. A region-specific degeneration of neurons in the dorsal cochlear nucleus (DCN) and posteroventral cochlear nucleus (PVCN) by 50% was found. Degeneration of neurons in the anteroventral cochlear nucleus (AVCN) was not found. An imbalance between excitatory and inhibitory synaptic transmission after de-afferentation may have played a crucial role in the development of neuronal cell demise in the CN. The occurrence of a region-specific loss of adult CN neurons illustrates the importance of evaluating all regions of the CN to investigate the effects of de-afferentation. Thus, this experimental model may be promising to obtain not only the basic knowledge on auditory nerve/CN degeneration but also the information relevant to the application of cochlear or auditory brainstem implants.
Sekiya
Tetsuji
T
Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Sakyou-ku, Kyoto 606-8507, Japan. tsekiya@ent.kuhp.kyoto-u.ac.jp
Canlon
Barbara
B
Viberg
Agneta
A
Matsumoto
Masahiro
M
Kojima
Ken
K
Ono
Kazuya
K
Yoshida
Atsuhiro
A
Kikkawa
Yayoi S
YS
Nakagawa
Takayuki
T
Ito
Juichi
J
D000818:Animals; D002470:Cell Survival / Q000502:physiology; D003056:Cochlear Nerve; D017626:Cochlear Nucleus / Q000473:pathology*; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D008297:Male; D009408:Nerve Compression Syndromes / Q000473:pathology* / Q000503:physiopathology*; D009410:Nerve Degeneration / Q000473:pathology*; D010812:Physical Stimulation / Q000009:adverse effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000502:physiology*; D013238:Stereotaxic Techniques