Glycine Receptors in Adult Guinea Pig Brain Stem Auditory Nuclei: Regulation after Unilateral Cochlear Ablation

Suneja, Sanoj K.; Benson, Christina G.; Potashner, S.J.

doi:10.1006/exnr.1998.6946

Cited by 113 publications

(96 citation statements)

References 107 publications

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“…The CN subdivisions and the LSO bound 0.12 -0.18 fmols of strychnine per mg of tissue protein, while the MSO and IC bound approximately 0.08 fmols per mg protein (Fig. 1, white bars).The relative levels of binding activity determined in the present 400 μm-thick samples of the auditory nuclei, quantified with liquid scintillation spectrometry, were similar to those observed in 15 μm-thick samples, quantified autoradiographically (Suneja et al, 1998a). The autoradiographic study indicated that the distribution of binding activity was similar to that of high glycine concentrations, suggesting a corresponding distribution of receptors and glycine presumed to be in presynaptic endings.…”

Section: Resultssupporting

confidence: 71%

“…It is conceivable, therefore, that the actions of protein kinases might be involved in the change of glycinergic receptor activity after UCA. To assess this possibility, we quantified the specific binding of [ 3 H]strychnine, using microdissected slices of brain stem auditory nuclei 145 days after UCA, when the deficit in glycine receptor activity is fully developed (Suneja et al, 1998a;Potashner et al, 2000). We compared this binding activity to that in tissues of agematched, unlesioned control animals.…”

Section: Introductionmentioning

confidence: 99%

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Protein kinases regulate glycine receptor binding in brain stem auditory nuclei after unilateral cochlear ablation

2007

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Glycinergic synaptic inhibition is part of acoustic information processing in brain stem auditory pathways and contributes to the regulation of neuronal excitation. We found previously that unilateral cochlear ablation (UCA) in young adult guinea pigs decreased [ 3 H]strychnine binding activity in several brain stem auditory nuclei. This study determined if the UCA-induced deficit could be regulated by protein kinase C (PKC), protein kinase A (PKA) or Ca 2+ /calmodulin-dependent protein kinase II (CaMKII). The specific binding of [ 3 H]strychnine was measured in slices of the dorsal (DCN), posteroventral (PVCN) and anteroventral (AVCN) cochlear nucleus (CN), the lateral (LSO) and medial (MSO) superior olive, and the inferior colliculus (IC) 145 days after UCA. Tissues from age-matched unlesioned animals served as controls. UCA induced deficits in specific binding in the AVCN, PVCN and LSO on the ablated side and in the MSO bilaterally. These deficits were reversed by 3 μM phorbol 1,2-dibutyrate, a PKC activator, or 0.2 mM dibutyryl-cAMP, a PKA activator. However, 50 nM Ro31-8220, a PKC inhibitor, and 2 μM H-89, a PKA inhibitor, had no effect in unlesioned controls and after UCA. In contrast, 4 μM KN-93, a CaMKII inhibitor, relieved or reversed the UCA-induced binding deficits and elevated binding in the IC. These findings suggest a UCA-induced down regulation of glycine receptor synthesis may have occurred via reduced phosphorylation of proteins that control receptor synthesis; this effect was reversed by diminishing CaMKII activity or increasing PKC and PKA activity.

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Section: Resultssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Protein kinases regulate glycine receptor binding in brain stem auditory nuclei after unilateral cochlear ablation

2007

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“…Long lasting effects at lower stages have been induced by lesions, for instance of one cochlea, leading to an altered balance of excitation and inhibition (McAlpine et al 1997). This may be due to a permanent decrease in the efficacy of inhibitory connections as, for instance, glycine receptors are permanently down regulated in the IC opposite to a cochleaectomy (Suneja et al 1998;Argence et al 2006). …”

Section: Discussionmentioning

confidence: 99%

Dynamic changes in level influence spatial coding in the lateral superior olive

Park¹,

Brand

Koch

et al. 2008

Hearing Research

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It is well established that the responses of binaural auditory neurons can adapt and change dramatically depending on the nature of a preceding sound. Examples of how the effects of ensuing stimuli play a functional role in auditory processing include motion sensitivity and precedence-like effects. To date, these types of effects have been documented at the level of the midbrain and above. Little is known about sensitivity to ensuing stimuli below in the superior olivary nuclei where binaural response properties are first established. Here we report on single cell responses in the gerbil lateral superior olive, the initial site where sensitivity to interaural level differences is established. In contrast to our expectations we found a robust sensitivity to ensuing stimuli. The majority of the cells we tested (86%), showed substantial suppression and/or enhancement to a designated target stimulus, depending on the nature of a preceding stimulus. Hence, sensitivity to ensuing stimuli is already established at the first synaptic station of binaural processing.

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“…A variety of evidence from prior studies suggests that inhibitory synapses in auditory neurons are weaker following cochlear damage or ablation (Willott et al 1997;Suneja et al 1998;Milbrandt et al 2000;Mossop et al 2000;Vale and Sanes 2000;Vale et al 2003Vale et al , 2004. Moreover, inhibitory effects on spike trains have been shown to be weaker following AT in the inferior colliculus and dorsal cochlear nucleus Ma and Young 2006).…”

Section: Rate Functions Of Primary-and Non-primary-like Neurons Aftermentioning

confidence: 99%

Encoding Intensity in Ventral Cochlear Nucleus Following Acoustic Trauma: Implications for Loudness Recruitment

Cai

Young

2008

JARO

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Loudness recruitment, an abnormally rapid growth of perceived loudness with sound level, is a common symptom of sensorineural hearing loss. Following acoustic trauma, auditory-nerve rate responses are reduced, and rate grows more slowly with sound level, which seems inconsistent with recruitment (Heinz et al., J. Assoc. Res. Otolaryngol. 6:91-105, 2005). However, rate-level functions (RLFs) in the central nervous system may increase in either slope or saturation value following trauma (e.g., Salvi et al., Hear. Res. 147:261-274, 2000), suggesting that recruitment may arise from central changes. In this paper, we studied RLFs of neurons in ventral cochlear nucleus (VCN) of the cat after acoustic trauma. Trauma did not change the general properties of VCN neurons, and the usual VCN functional classifications remained valid (chopper, primary-like, onset, etc.). After trauma, non-primary-like neurons, most noticeably choppers, exhibited elevated maximum discharge rates and steeper RLFs for frequencies at and near best frequency (BF). Primary-like neurons showed the opposite changes. To relate the neurons' responses to recruitment, rate-balance functions were computed; these show the sound level required to give equal rates in a normal and a traumatized ear and are analogous to loudness balance functions that show the sound levels giving equal perceptual loudness in the two ears of a monaurally hearing-impaired person. The ratebalance functions showed recruitment-like steepening of their slopes in non-primary-like neurons in all conditions. However, primary-like neurons showed recruitment-like behavior only when rates were summated across neurons of all BFs. These results suggest that the non-primary-like, especially chopper, neurons may be the most peripheral site of the physiological changes in the brain that underlie recruitment.

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Glycine Receptors in Adult Guinea Pig Brain Stem Auditory Nuclei: Regulation after Unilateral Cochlear Ablation

Cited by 113 publications

References 107 publications

Protein kinases regulate glycine receptor binding in brain stem auditory nuclei after unilateral cochlear ablation

Protein kinases regulate glycine receptor binding in brain stem auditory nuclei after unilateral cochlear ablation

Dynamic changes in level influence spatial coding in the lateral superior olive

Encoding Intensity in Ventral Cochlear Nucleus Following Acoustic Trauma: Implications for Loudness Recruitment

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