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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.


Group results (n = 9) showing time windows over which a synergistic interaction exists between SS and BMI in enhancing the amplitude of an LFP recorded at the BF of a recording site. (A–C) are based on results obtained at 10, 20, and 30 dB above the MT of a recording site. In (A–C), a white line with a black background in the bottom panel is a p-value by time function showing statistical significance of the difference between the total changes caused by individual and simultaneous applications of SS and BMI.
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Figure 6: Group results (n = 9) showing time windows over which a synergistic interaction exists between SS and BMI in enhancing the amplitude of an LFP recorded at the BF of a recording site. (A–C) are based on results obtained at 10, 20, and 30 dB above the MT of a recording site. In (A–C), a white line with a black background in the bottom panel is a p-value by time function showing statistical significance of the difference between the total changes caused by individual and simultaneous applications of SS and BMI.

Mentions: We examined the time window over which SS and BMI had a synergistic interaction in regulating LFPs. Two waveforms were formed at each sound-pressure level (10, 20, or 30 dB above the MT) for each case. One was a difference waveform between the LFPs obtained before and during simultaneous application of SS and BMI (reflecting a total increase caused by the drugs applied simultaneously). The other one was the sum of the two difference waveforms resulting from individual applications of the drugs (reflecting a total increase caused by the drugs applied individually). Pairs of these waveforms from nine individual cases were utilized to generate two grand-mean waveforms (Figures 6A–C upper panels). At each of the 6104 sampling points (250 ms recording trace sampled at 24.414 kHz), we examined the disparity between the total increase caused by SS and BMI applied simultaneously and the total increases caused by the drugs applied individually (Wilcoxon signed-rank test, data from nine cases). Such a disparity was used to reflect a synergistic interaction between SS and BMI. At 10 dB above the MT, a disparity (p < 0.05) existed at all sampling points within a time window between 13.8 and 26.1 ms after the onset of a stimulus (Figure 6A). Similar time windows of interaction were observed at 20 and 30 dB above the MT (13.1–26.2 and 13.4–26.2 ms after the onset of a stimulus, respectively) (Figures 6B,C).


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)

Group results (n = 9) showing time windows over which a synergistic interaction exists between SS and BMI in enhancing the amplitude of an LFP recorded at the BF of a recording site. (A–C) are based on results obtained at 10, 20, and 30 dB above the MT of a recording site. In (A–C), a white line with a black background in the bottom panel is a p-value by time function showing statistical significance of the difference between the total changes caused by individual and simultaneous applications of SS and BMI.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Group results (n = 9) showing time windows over which a synergistic interaction exists between SS and BMI in enhancing the amplitude of an LFP recorded at the BF of a recording site. (A–C) are based on results obtained at 10, 20, and 30 dB above the MT of a recording site. In (A–C), a white line with a black background in the bottom panel is a p-value by time function showing statistical significance of the difference between the total changes caused by individual and simultaneous applications of SS and BMI.
Mentions: We examined the time window over which SS and BMI had a synergistic interaction in regulating LFPs. Two waveforms were formed at each sound-pressure level (10, 20, or 30 dB above the MT) for each case. One was a difference waveform between the LFPs obtained before and during simultaneous application of SS and BMI (reflecting a total increase caused by the drugs applied simultaneously). The other one was the sum of the two difference waveforms resulting from individual applications of the drugs (reflecting a total increase caused by the drugs applied individually). Pairs of these waveforms from nine individual cases were utilized to generate two grand-mean waveforms (Figures 6A–C upper panels). At each of the 6104 sampling points (250 ms recording trace sampled at 24.414 kHz), we examined the disparity between the total increase caused by SS and BMI applied simultaneously and the total increases caused by the drugs applied individually (Wilcoxon signed-rank test, data from nine cases). Such a disparity was used to reflect a synergistic interaction between SS and BMI. At 10 dB above the MT, a disparity (p < 0.05) existed at all sampling points within a time window between 13.8 and 26.1 ms after the onset of a stimulus (Figure 6A). Similar time windows of interaction were observed at 20 and 30 dB above the MT (13.1–26.2 and 13.4–26.2 ms after the onset of a stimulus, respectively) (Figures 6B,C).

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.