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Local Application of Sodium Salicylate Enhances Auditory Responses in the Rat's Dorsal Cortex of the Inferior Colliculus.

Patel CR, Zhang H - Front Neurol (2014)

Bottom Line: Sodium salicylate (SS) is a widely used medication with side effects on hearing.Simultaneous application of the drug and a GABAergic receptor agonist produced an effect different from the sum of effects produced by the two drugs released individually.Our results indicate that SS can affect sound-driven activity in the ICd by modulating local GABAergic inhibition.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Windsor , Windsor, ON , Canada.

ABSTRACT
Sodium salicylate (SS) is a widely used medication with side effects on hearing. In order to understand these side effects, we recorded sound-driven local-field potentials in a neural structure, the dorsal cortex of the inferior colliculus (ICd). Using a microiontophoretic technique, we applied SS at sites of recording and studied how auditory responses were affected by the drug. Furthermore, we studied how the responses were affected by combined local application of SS and an agonists/antagonist of the type-A or type-B γ-aminobutyric acid receptor (GABAA or GABAB receptor). Results revealed that SS applied alone enhanced auditory responses in the ICd, indicating that the drug had local targets in the structure. Simultaneous application of the drug and a GABAergic receptor antagonist synergistically enhanced amplitudes of responses. The synergistic interaction between SS and a GABAA receptor antagonist had a relatively early start in reference to the onset of acoustic stimulation and the duration of this interaction was independent of sound intensity. The interaction between SS and a GABAB receptor antagonist had a relatively late start, and the duration of this interaction was dependent on sound intensity. Simultaneous application of the drug and a GABAergic receptor agonist produced an effect different from the sum of effects produced by the two drugs released individually. These differences between simultaneous and individual drug applications suggest that SS modified GABAergic inhibition in the ICd. Our results indicate that SS can affect sound-driven activity in the ICd by modulating local GABAergic inhibition.

No MeSH data available.


An example showing the interaction between SS and Bac. (A) Left panel: LFPs evoked by a tone burst at the BF (19.0 kHz) and 20 dB above the MT of the recording site [as indicated by an arrow in the top left panel of (B)] before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (A) Right panel: difference waveforms showing changes caused by individual and simultaneous applications of SS and Bac. Also, shown in this panel is a waveform resulting from summation of changes caused by individual applications of SS and Bac. (B) Left panels: amplitude by sound-pressure level (top) and amplitude by sound-frequency (bottom) functions obtained before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (B) Right panels: changes in the peak amplitude of an LFP caused by individual and simultaneous applications of SS and Bac at various sound-pressure levels (top) and frequencies (bottom). Also, shown in each of the two panels is a curve resulting from summation of changes caused by individual applications of SS and Bac.
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Figure 11: An example showing the interaction between SS and Bac. (A) Left panel: LFPs evoked by a tone burst at the BF (19.0 kHz) and 20 dB above the MT of the recording site [as indicated by an arrow in the top left panel of (B)] before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (A) Right panel: difference waveforms showing changes caused by individual and simultaneous applications of SS and Bac. Also, shown in this panel is a waveform resulting from summation of changes caused by individual applications of SS and Bac. (B) Left panels: amplitude by sound-pressure level (top) and amplitude by sound-frequency (bottom) functions obtained before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (B) Right panels: changes in the peak amplitude of an LFP caused by individual and simultaneous applications of SS and Bac at various sound-pressure levels (top) and frequencies (bottom). Also, shown in each of the two panels is a curve resulting from summation of changes caused by individual applications of SS and Bac.

Mentions: The GABAB receptor agonist Bac was released individually and in combination with SS in seven cases, as shown by an example in Figure 11. Bac consistently suppressed the DN with or without the presence of SS. Difference waveforms indicated that the change caused by SS and Bac applied simultaneously was different from the sum of changes caused by the two drugs applied individually, suggesting that the drugs interacted with each other in regulating an LFP (Figures 11A,B right panels). The interaction between SS and Bac was observed over a wide range of frequencies and intensities (Figure 11B).


Local Application of Sodium Salicylate Enhances Auditory Responses in the Rat's Dorsal Cortex of the Inferior Colliculus.

Patel CR, Zhang H - Front Neurol (2014)

An example showing the interaction between SS and Bac. (A) Left panel: LFPs evoked by a tone burst at the BF (19.0 kHz) and 20 dB above the MT of the recording site [as indicated by an arrow in the top left panel of (B)] before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (A) Right panel: difference waveforms showing changes caused by individual and simultaneous applications of SS and Bac. Also, shown in this panel is a waveform resulting from summation of changes caused by individual applications of SS and Bac. (B) Left panels: amplitude by sound-pressure level (top) and amplitude by sound-frequency (bottom) functions obtained before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (B) Right panels: changes in the peak amplitude of an LFP caused by individual and simultaneous applications of SS and Bac at various sound-pressure levels (top) and frequencies (bottom). Also, shown in each of the two panels is a curve resulting from summation of changes caused by individual applications of SS and Bac.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231951&req=5

Figure 11: An example showing the interaction between SS and Bac. (A) Left panel: LFPs evoked by a tone burst at the BF (19.0 kHz) and 20 dB above the MT of the recording site [as indicated by an arrow in the top left panel of (B)] before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (A) Right panel: difference waveforms showing changes caused by individual and simultaneous applications of SS and Bac. Also, shown in this panel is a waveform resulting from summation of changes caused by individual applications of SS and Bac. (B) Left panels: amplitude by sound-pressure level (top) and amplitude by sound-frequency (bottom) functions obtained before drug, during individual and simultaneous applications of SS and Bac, and after recovery. (B) Right panels: changes in the peak amplitude of an LFP caused by individual and simultaneous applications of SS and Bac at various sound-pressure levels (top) and frequencies (bottom). Also, shown in each of the two panels is a curve resulting from summation of changes caused by individual applications of SS and Bac.
Mentions: The GABAB receptor agonist Bac was released individually and in combination with SS in seven cases, as shown by an example in Figure 11. Bac consistently suppressed the DN with or without the presence of SS. Difference waveforms indicated that the change caused by SS and Bac applied simultaneously was different from the sum of changes caused by the two drugs applied individually, suggesting that the drugs interacted with each other in regulating an LFP (Figures 11A,B right panels). The interaction between SS and Bac was observed over a wide range of frequencies and intensities (Figure 11B).

Bottom Line: Sodium salicylate (SS) is a widely used medication with side effects on hearing.Simultaneous application of the drug and a GABAergic receptor agonist produced an effect different from the sum of effects produced by the two drugs released individually.Our results indicate that SS can affect sound-driven activity in the ICd by modulating local GABAergic inhibition.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Windsor , Windsor, ON , Canada.

ABSTRACT
Sodium salicylate (SS) is a widely used medication with side effects on hearing. In order to understand these side effects, we recorded sound-driven local-field potentials in a neural structure, the dorsal cortex of the inferior colliculus (ICd). Using a microiontophoretic technique, we applied SS at sites of recording and studied how auditory responses were affected by the drug. Furthermore, we studied how the responses were affected by combined local application of SS and an agonists/antagonist of the type-A or type-B γ-aminobutyric acid receptor (GABAA or GABAB receptor). Results revealed that SS applied alone enhanced auditory responses in the ICd, indicating that the drug had local targets in the structure. Simultaneous application of the drug and a GABAergic receptor antagonist synergistically enhanced amplitudes of responses. The synergistic interaction between SS and a GABAA receptor antagonist had a relatively early start in reference to the onset of acoustic stimulation and the duration of this interaction was independent of sound intensity. The interaction between SS and a GABAB receptor antagonist had a relatively late start, and the duration of this interaction was dependent on sound intensity. Simultaneous application of the drug and a GABAergic receptor agonist produced an effect different from the sum of effects produced by the two drugs released individually. These differences between simultaneous and individual drug applications suggest that SS modified GABAergic inhibition in the ICd. Our results indicate that SS can affect sound-driven activity in the ICd by modulating local GABAergic inhibition.

No MeSH data available.