Spiral ganglion cell density in young and old gerbils

Keithley, Elizabeth M.; Ryan, Allen F.; Woolf, Nigel K.

doi:10.1016/0378-5955(89)90134-2

Cited by 106 publications

(57 citation statements)

References 15 publications

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“…Aged rodents exhibit a number of age-related peripheral auditory changes, including a sloping lowfrequency loss of outer-hair cells and a small loss of apical and basal inner-hair cells (for review, see Willott, 1991;Saitoh et al, 1994;Gratton et al, 1996Gratton et al, , 1997Spongr et al, 1997;Ingham et al, 1999; and auditory nerve fiber loss (Keithley et al, 1989(Keithley et al, , 1992Dazert et al, 1996;Schmiedt et al, 1996). As in the present study, decreased acoustic nerve input activity into the DCN resulted in neurochemical evidence of a downregulation of putative glycinergic inhibition (Potashner et Figure 3.…”

Section: Discussionsupporting

confidence: 57%

Age-Related Changes in the Inhibitory Response Properties of Dorsal Cochlear Nucleus Output Neurons: Role of Inhibitory Inputs

Caspary

Schatteman²,

Hughes³

2005

J. Neurosci.

161

114

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Age-related hearing loss frequently results in a loss in the ability to discriminate speech signals, especially in noise. This is attributable, in part, to a loss in temporal resolving power and ability to adjust dynamic range. Circuits in the adult dorsal cochlear nucleus (DCN) have been shown to preserve signal in background noise. Fusiform cells, major DCN output neurons, receive focused glycinergic inputs from tonotopically aligned vertical cells that also project to the ventral cochlear nucleus. Glycine-mediated inhibition onto fusiform cells results in decreased tone-evoked activity as intensity is increased at frequencies adjacent to characteristic frequency (CF). DCN output is thus shaped by glycinergic inhibition, which can be readily assessed in recordings from fusiform cells. Previous DCN studies suggest an age-related loss of markers for glycinergic neurotransmission. The present study postulated that response properties of aged fusiform cells would show a loss of inhibition, resembling conditions observed with glycine receptor blockade. The functional impact of aging was examined by comparing response properties from units meeting fusiform-cell criteria in young and aged rats. Fusiform cells in aged animals displayed significantly higher maximum discharge rates to CF tones than those recorded from young-adult animals. Fusiform cells of aged rats displayed significantly fewer nonmonotonic CF rate-level functions and an age-related change in temporal response properties. These findings are consistent with an age-related loss of glycinergic input, likely from vertical cells, and with findings from other sensory aging studies suggesting a selective age-related decrement in inhibitory amino acid neurotransmitter function.

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Section: Discussionsupporting

confidence: 57%

Age-Related Changes in the Inhibitory Response Properties of Dorsal Cochlear Nucleus Output Neurons: Role of Inhibitory Inputs

Caspary

Schatteman²,

Hughes³

2005

J. Neurosci.

161

114

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“…Spiral ganglion cells degenerate in presbycusis in many species including human, rat, gerbil and mouse, mostly in response to hair cell loss (Schuknecht, 1964;Keithley et al, 1989;Keithley et al, 1992;Saitoh et al, 1994). The decrease in cell density in CBA/J is apparent at 18 months, a time when outer hair cell loss also becomes evident and the loss is of similar magnitude (20 − 25%) as reported by Willott et al (1991).…”

Section: Degeneration Of Spiral Ganglion Cellssupporting

confidence: 63%

“…Mongolian gerbils are considered a model for strial presbycusis (Mills et al, 1990) associated with strial atrophy and a decreased endocochlear potential (Schmiedt, 1996;Gratton et al, 1996). Decreased cochlear blood flow (Prazma et al, 1990), degeneration of spiral ganglion cells (Keithley et al, 1989;Suryadevara et al, 2001), and fibrocyte vacuolization and interstitial edema in the spiral ligament are also observed in gerbils (Spicer et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Age-related auditory pathology in the CBA/J mouse

et al. 2008

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Commercially obtained aged male CBA/J mice presented a complex pattern of hearing loss and morphological changes. A significant threshold shift in auditory brainstem responses (ABR) occurred at 3 months of age at 4 kHz without apparent loss of hair cells, rising slowly at later ages accompanied by loss of apical hair cells. A delayed high-frequency deficit started at 24 kHz around the age of 12 months. At 20 to 26 months, threshold shifts at 12 and 24 kHz and the accompanying hair cell loss at the base of the cochlea were highly variable with some animals appearing almost normal and others showing large deficits. Spiral ganglion cells degenerated by 18 months in all regions of the cochlea, with cell density reduced by approximately 25%. There was no degeneration of the stria vascularis and the endocochlear potential remained stable from 3 to 25 months of age regardless of whether the animals had normal or highly elevated ABR thresholds. The slow high frequency hearing loss combined with a modest reduction of ganglion cell density and an unchanged endocochlear potential suggest sensorineural presbycusis. The superimposed early hearing loss at low frequencies, which is not seen in animals bred in-house, may complicate the use of these animals as a presbycusis model.

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“…Previous studies have shown that age-related hearing loss in quiet-reared gerbils is commonly associated with pathologies in the lateral wall and stria vascularis, resulting in a chronically reduced EP (Schulte and Schmiedt 1992;Gratton et al 1996Gratton et al , 1997Spicer et al 1997;Spicer and Schulte 2002). Neuronal loss in Rosenthal's canal is also seen in aged gerbils (Keithley et al 1989;Slepecky et al 2000;Suryadevara et al 2001;Mills et al 2006). However, because of the complexity of histopathological changes in aged cochleas, it has been difficult to isolate the role of a chronic reduction in the EP in producing functional changes in auditory response properties.…”

Section: Discussionmentioning

confidence: 97%

Chronic Reduction of Endocochlear Potential Reduces Auditory Nerve Activity: Further Confirmation of an Animal Model of Metabolic Presbyacusis

Lang

Jyothi

Smythe

et al. 2010

JARO

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Gerbils aged in quiet show a decline of the endocochlear potential (EP) and elevated auditory nerve compound action potential (CAP) thresholds. However, establishing a direct relationship between an age-related reduction in the EP and changes in the activities of primary auditory neurons is difficult owing to the complexity of age-related histological changes in the cochlea. To address this issue, we developed a young gerbil model of "metabolic" presbyacusis that uses an osmotic pump to deliver furosemide into the round window niche for 7 days, resulting in a chronically reduced EP. In this model, the only major histopathologic changes were restricted to the hook region of the cochlea and consisted of loss of strial intermediate cells and massive edema in the lateral wall. The morphological and physiological evidence suggests that the cochlea can adapt to furosemide application over time. The morphology of spiral ganglion cells and hair cells appeared normal throughout the cochlea. CAP responses and EP values in this model are similar to those of quiet-aged ears. The spontaneous activity of single auditory fibers (n= 188) was assessed in 15 young gerbils treated with furosemide for 7 days. The percentage of recorded low-spontaneous rate (SR) fibers at characteristic frequencies (CFs)≥6 kHz was significantly lower in furosemide-treated than in control ears. Recovery function tests of CAP responses after prior stimulation also showed a decline in activity of the low-SR population with CFs≥6 kHz in the treated cochleas. A similar loss in the activity of low-SR fiber has been previously shown in quiet-aged gerbils. These results suggest that dysfunction of the cochlear lateral wall and subsequent chronic reduction in the EP can directly affect the activity patterns of primary auditory neurons in a manner similar to that seen in aged gerbils.

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Spiral ganglion cell density in young and old gerbils

Cited by 106 publications

References 15 publications

Age-Related Changes in the Inhibitory Response Properties of Dorsal Cochlear Nucleus Output Neurons: Role of Inhibitory Inputs

Age-Related Changes in the Inhibitory Response Properties of Dorsal Cochlear Nucleus Output Neurons: Role of Inhibitory Inputs

Age-related auditory pathology in the CBA/J mouse

Chronic Reduction of Endocochlear Potential Reduces Auditory Nerve Activity: Further Confirmation of an Animal Model of Metabolic Presbyacusis

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