Short-term adaptation in the peripheral auditory system is related to the AMPA receptor.
The role of glutamate receptors was investigated by infusing N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-isoxazol-propionate (AMPA) into the guinea pig cochlea. Auditory brainstem response thresholds and forward masking were used to determine auditory sensitivity. In the presence of 330 microM NMDA, the auditory brainstem response (ABR) thresholds were elevated by 20-30 dB at 2 kHz and 8 kHz, and the slopes of the forward masking curves were not significantly different from controls. When a high concentration of NMDA (15 mM) was used, ABR thresholds were elevated by 40-50 dB at 2 kHz and 8 kHz and the slopes of the forward masking curves were significantly decreased. In contrast, when AMPA (150 microM) was infused, ABR thresholds were elevated by 20-35 dB at 2 and 8 kHz and the slopes of the forward masking curves were significantly decreased from the control group. When the concentration of AMPA was decreased (100 microM). ABR thresholds were not significantly altered but the slopes of the forward masking curves were significantly decreased from control values. The present study suggests that AMPA receptors play a significantly more important role in short-term adaptation than NMDA receptors.
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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Duan
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Canlon
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D003051:Cochlea / Q000166:cytology / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem; D006168:Guinea Pigs; D016202:N-Methylaspartate / Q000494:pharmacology; D010470:Perceptual Masking; D018091:Receptors, AMPA / Q000502:physiology*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D018091:Receptors, AMPA; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid