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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 = 26) showing the time window over which SS enhances the amplitude of an LFP recorded at the BF of the recording site. (A–C) are based on LFPs recorded at 10, 20, and 30 dB above the MT of a recording site. In the upper panels of (A–C), dotted and dashed lines represent grand-mean waveforms of LFPs recorded before and during SS, respectively. A solid black line is the difference between two grand-mean waveforms. A white line with a black background is a p-value (Wilcoxon signed-rank test) by time function comparing the difference between the amplitudes of the two grand-mean waveforms.
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Figure 3: Group results (n = 26) showing the time window over which SS enhances the amplitude of an LFP recorded at the BF of the recording site. (A–C) are based on LFPs recorded at 10, 20, and 30 dB above the MT of a recording site. In the upper panels of (A–C), dotted and dashed lines represent grand-mean waveforms of LFPs recorded before and during SS, respectively. A solid black line is the difference between two grand-mean waveforms. A white line with a black background is a p-value (Wilcoxon signed-rank test) by time function comparing the difference between the amplitudes of the two grand-mean waveforms.

Mentions: We examined the time window over which SS significantly increased the amplitude of an LFP (Figure 3). At each specific stimulus level, two LFPs recorded before and during application of SS were paired for each of the 26 cases. The resulting 26 pairs of LFPs were used to generate two grand-mean waveforms (top panels in Figures 3A–C). Each waveform (either a recorded trace or a grand mean) had 6104 data points, as a recording was conducted over a 250 ms period at a sampling rate of 24.414 kHz. A Wilcoxon signed-rank test was conducted at each of these 6104 points using 26 pairs of amplitude values obtained before and during application of SS. A resulting p-value was used to indicate the level of significance of the change caused by SS at this sampling point. A p-value by time curve obtained at 10 dB above the MT indicated that SS significantly increased the amplitude of an LFP (p < 0.05) at all points over a time window between 13.8 and 48.1 ms after the onset of a stimulus (bottom panel in Figure 3A). This time window was to some extent wider at higher stimulus levels (compare Figures 3B,C bottom panels with the Figure 3A bottom panel).


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 = 26) showing the time window over which SS enhances the amplitude of an LFP recorded at the BF of the recording site. (A–C) are based on LFPs recorded at 10, 20, and 30 dB above the MT of a recording site. In the upper panels of (A–C), dotted and dashed lines represent grand-mean waveforms of LFPs recorded before and during SS, respectively. A solid black line is the difference between two grand-mean waveforms. A white line with a black background is a p-value (Wilcoxon signed-rank test) by time function comparing the difference between the amplitudes of the two grand-mean waveforms.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Group results (n = 26) showing the time window over which SS enhances the amplitude of an LFP recorded at the BF of the recording site. (A–C) are based on LFPs recorded at 10, 20, and 30 dB above the MT of a recording site. In the upper panels of (A–C), dotted and dashed lines represent grand-mean waveforms of LFPs recorded before and during SS, respectively. A solid black line is the difference between two grand-mean waveforms. A white line with a black background is a p-value (Wilcoxon signed-rank test) by time function comparing the difference between the amplitudes of the two grand-mean waveforms.
Mentions: We examined the time window over which SS significantly increased the amplitude of an LFP (Figure 3). At each specific stimulus level, two LFPs recorded before and during application of SS were paired for each of the 26 cases. The resulting 26 pairs of LFPs were used to generate two grand-mean waveforms (top panels in Figures 3A–C). Each waveform (either a recorded trace or a grand mean) had 6104 data points, as a recording was conducted over a 250 ms period at a sampling rate of 24.414 kHz. A Wilcoxon signed-rank test was conducted at each of these 6104 points using 26 pairs of amplitude values obtained before and during application of SS. A resulting p-value was used to indicate the level of significance of the change caused by SS at this sampling point. A p-value by time curve obtained at 10 dB above the MT indicated that SS significantly increased the amplitude of an LFP (p < 0.05) at all points over a time window between 13.8 and 48.1 ms after the onset of a stimulus (bottom panel in Figure 3A). This time window was to some extent wider at higher stimulus levels (compare Figures 3B,C bottom panels with the Figure 3A bottom panel).

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.