Morphologic and neurochemical abnormalities in the auditory brainstem of the genetically epilepsy-prone hamster (GPG/Vall).
OBJECTIVE
This study was performed to evaluate whether audiogenic seizures, in a strain of genetically epilepsy-prone hamsters (GPG/Vall), might be associated with morphologic alterations in the cochlea and auditory brainstem. In addition, we used parvalbumin as a marker of neurons with high levels of activity to examine changes within neurons.


METHODS
Cochlear histology as well as parvalbumin immunohistochemistry were performed to assess possible abnormalities in the GPG/Vall hamster. Densitometry also was used to quantify levels of parvalbumin immunostaining within neurons and fibers in auditory nuclei.


RESULTS
In the present study, missing outer hair cells and spiral ganglion cells were observed in the GPG/Vall hamster. In addition, an increase was noted in the size of spiral ganglion cells as well as a decrease in the volume and cell size of the cochlear nucleus (CN), the superior olivary complex nuclei (SOC), and the nuclei of the lateral lemniscus (LL) and the inferior colliculus (IC). These alterations were accompanied by an increase in levels of parvalbumin immunostaining within CN, SOC, and LL neurons, as well as within parvalbumin-immunostained fibers in the CN and IC.


CONCLUSIONS
These data are consistent with a cascade of atrophic changes starting in the cochlea and extending along the auditory brainstem in an animal model of inherited epilepsy. Our data also show an upregulation in parvalbumin immunostaining in the neuropil of the IC that may reflect a protective mechanism to prevent cell death in the afferent sources to this nucleus.
Fuentes-Santamaría
Verónica
V
Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1010, U.S.A. vfuentes@wfubmc.edu
Cantos
Raquel
R
Alvarado
Juan Carlos
JC
García-Atarés
Natividad
N
López
Dolores E
DE
D000818:Animals; D001306:Auditory Pathways / Q000378:metabolism* / Q000473:pathology*; D001933:Brain Stem / Q000378:metabolism* / Q000473:pathology*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D048429:Cell Size; D003051:Cochlea / Q000378:metabolism* / Q000473:pathology*; D017626:Cochlear Nucleus / Q000378:metabolism / Q000473:pathology; D004396:Coloring Agents; D006224:Cricetinae; D004195:Disease Models, Animal; D004827:Epilepsy / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D020195:Epilepsy, Reflex / Q000235:genetics / Q000378:metabolism; D007090:Image Interpretation, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D009410:Nerve Degeneration / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D019581:Neuropil / Q000378:metabolism / Q000473:pathology; D010320:Parvalbumins / Q000378:metabolism; D017111:Phodopus; D015854:Up-Regulation / Q000235:genetics
D002135:Calcium-Binding Proteins; D004396:Coloring Agents; D010320:Parvalbumins